Doug Kaufman has been with Babcox Media since 1987 serving in a variety of editorial and publishing roles and titles. He is currently publisher of Engine Builder. He also has been editorial liaison between Babcox and the National Association for Stock Car Auto Racing (NASCAR) for the past 12 years. Doug has a Bachelor of Science in Journalism from Bowling Green State University and remains a committed MAC enthusiast.
Doug Kaufman discusses no-start and no-crank issues on vehicles with transponder keys, and how these keys introduce different diagnostic processes and tools you can use to find the problem. Sponsored by Blue Streak.
The positive crankcase ventilation (PCV) valve is a little component that can cause big problems if it isn’t working. Neither your customer’s engine nor your job profitability will flourish if you don’t properly diagnose PCV leaks.
The PCV system prevents crankcase blowby vapors from escaping into the atmosphere by capturing the vapors, separating the oil, and directing them into the intake manifold so they can be burned in the engine. Even a small, seemingly insignificant leak can illuminate an engine light because it can introduce unmetered air into the engine.
Mounted in the valve cover and connected to the intake manifold, throttle body or air cleaner with a large vacuum hose, the PCV system plays an important role in vehicle performance. Some late-model systems may have a large plastic box attached to the side of the engine or valve cover. Inside the box is a series of baffles that help the oil droplet fall out of the vapors. The oil is then drained into the engine.
If your customer is complaining of any of the following problems, his or her car might have a malfunctioning PCV system. Oil consumption (without smoking), fouled plugs, rough idle, plugged and sticking oil rings, rapid/premature engine wear, ruptured gaskets and seals, oil in the air cleaner and potential detonation are all symptoms of a potentially ineffective or inoperative PCV system.
The system uses manifold vacuum to draw vapors from the crankcase into the intake manifold to be burned with the normal air/fuel mixture. The flow is controlled by the PCV valve in order to meter the amount of vapor introduced into the combustion process.
A neglected or poorly operating PCV system will quickly contaminate the engine oil and heavy sludge accumulations from the combustion process blow-by.
Testing The System
Testing the PCV system is relatively easy and can be done a number of different ways starting by just looking at the components. Does the PCV valve “feel” right? A quick check of the valve can be made by just shaking it and listening for a rattle, the absence of which indicates a blockage. Another option is to pull the valve from the valve cover and feel the end for vacuum while the engine is idling (no vacuum would indicate a blockage).
If you are dealing with an engine that has oil sludging problems or the system shows signs of over pressurization (detached hose or leaking seals), look to see if the PCV valve has an electric heater. Often the heater will fail and condensation will build up in the valve. When the water collects and freezes, the PCV valve will be blocked until the ice melts. Check the coil with an ohm meter to see if it has the correct resistance and is not open.
After running the engine up to operating temperature and allowing it to stabilize at idle, pinch or block off the hose between the vacuum source and the PCV valve. The engine should typically drop 50-80 rpm. If the engine does not change, check the PCV valve and system hoses for blockage. Replace components as necessary and retest.
Shut the engine off and block off the fresh air source to the engine. This would typically be the hose coming from the air cleaner to the rocker cover. Remove the dipstick tube and connect a vacuum-pressure gauge to the dipstick tube. Restart the engine and allow it to stabilize at idle. Then take a reading of your vacuum-pressure gauge. You should read 1-3˝ of vacuum with a normally operating PCV. If you have 0˝ of vacuum or even pressure you have problems.
If the engine has an external air leak you will not have an effective PCV system. This could be a leaking front cover, rocker cover, oil pan gasket, manifold end gaskets or any other host of potential leaks.
Looking For Leaks
Leaks in today’s cars are simply unacceptable. Modern vehicle systems can and will detect even the smallest amount of unmetered air, and you’ll need proper leak detection equipment to find it. In many situations under the hood, you can often find the source of the leak just by looking, but with air leaks – especially those coming in and not going out it can be more difficult to accurately track down.
With no fluid to drip and leave easy signs to follow for diagnosis, the smoke machine can be a valuable asset. With modern machines able to do more than just pump out smoke that can be drawn into a leaking PCV system, today’s equipment with incorporated pressure gauges, flow meters, control valves and connectors to isolate the system being tested will increase your diagnostic ability considerably.
Lighting is important for locating smoke, especially a small trickle of it. Many leak detectors come with a bright halogen or ultraviolet (UV) flashlight, which will reflect visibly off of the smoke vapors.
Although dye is most widely used in systems that have a liquid to carry the dye throughout, such as an A/C system, there are leak detection units for some systems that work with a special smoke solution, which suspends the fluorescent dye and carries it along where it will eventually accumulate around the area of the leak. Most work with a UV light that cause the dye to glow.
A recent study conducted by Goodyear Auto Service and Just Tires revealed that young drivers are less likely to be able to identify the tire pressure monitoring system (TPMS) warning light than the eye-roll emoji.
The fact is, even though the technology has been mandatory on all new cars and light trucks manufactured since 2007, a broad cross-section of the motoring public doesn’t understand the functionality of their tire pressure monitoring system.
Unfortunately, say some TPMS experts, many professionals aren’t that much more knowledgeable.
There is a perception among many drivers – as well as technicians – that TPMS has become such a universal product that one system fits all and that one service procedure will cure all ills. And, although tools have made things easier because they can handle more complex diagnostic tasks than ever before, the systems and sensors can still be complicated.
Over the past dozen years, close to 180 million light trucks and cars have been sold in the U.S. – they’ve all been equipped with TPMS. With a sensor inside each wheel, it’s clear that the service opportunities will only continue to expand. Training at the consumer and professional level will continue to be needed.
The life of a tire pressure sensor depends on the battery inside the sensor, and miles driven. The more miles that are driven, the more signals the sensors generate and the faster they use up their batteries.
There’s no sure way to tell for sure how long a battery will last – some estimates on the low end are 5-7 years while others on the high end give 8-10-year lifespans. Miles driven may be 12-15,000 miles per year, so it can be challenging to gauge accurately. Some experts say the life of a tire pressure sensor is about the same as a good set of high-quality tires with a high tread-life rating (500 or higher, which roughly translates to 75,000 miles or more depending on road conditions, type of driving and wheel alignment). Most sensors should last as long as the first set of original equipment tires, but they probably won’t last the full life of a second set of tires.
Published guidelines recommend servicing the TPMS sensors anytime a tire is removed from the wheel.
The market has pushed for a stand-alone solution or dedicated TPMS tool over the past decade because many tire-only locations haven’t typically needed an OBDII scan too. They only need something to be able to relearn the vehicle and program a sensor if they need to. So, the lion’s share of tools in use are dedicated TPMS tools that can do diagnostics, determine what’s wrong with the TPMS, and then provide the functions to replace the sensor and program the sensor IDs to the car.
Where this relearn procedure may be complicated is the number of options for replacement sensors. “It’s not just that one-to-one part replacement anymore,” says one aftermarket expert. “If you have a 2012 Chevy Impala in your shop and you think that it’s got OE sensors on it, think again – it’s seven years old, so it may or may not. A couple of the sensors may have been replaced with a couple of different aftermarket versions. And the problem is that the service kits for those sensors probably aren’t the same. But you’re a service provider. You don’t know that. You’re going to get in the job, start tearing everything apart, and then realize you might not have parts for some of the service kits.”
Many specialty TPMS suppliers offer service assortments that cover a wide variety of sensors including popular replacement sensors. Some specialty suppliers even have replenishment programs to make sure you have the service kits you need before you start a job.
Some suppliers say just a few part numbers can cover 80 to 85 percent of the market, eliminating the need to stock such a large variety of OEM SKUs. Some applications have clamp-in valve stems with a gasket and hex nut at the base, while others are snap-in with a traditional rubber valve stem. Some aftermarket sensors will fit either type of valve stem.
Some replacement sensors must be programmed to the vehicle application with a unique ID number that is associated with a specific wheel location. Many “universal” sensors also must be programmed with the proper protocol information before they will communicate and function correctly. Others come preprogrammed with multi-application software already installed and do not require any additional programming, saving installation time and reducing the chance of “installer error.”
Sensor manufacturers say they continue to conduct training sessions with tire dealers and undercar shops explaining what information the TPMS sensors are transmitting and how to understand it. Sensors are doing a better job recognizing tire speeds, pressures and tread life, and less frequent transmission cycles from the sensors mean the batteries last longer than ever.
Future technology may help to make the process even easier. Technology is reportedly being developed that will allow sensor batteries to be recharged by the motion of the wheel rotations.
In this video series, Engine Builder Editor Doug Kaufman will be sharing stories that engine builders have shared with him. Stories that make you want to laugh – or pull your hair out – or just say, “Yep just another day at work.” We’re sure many of you will relate.
Stop me if you’ve heard this story before: a couple of guys get ahold of a tired late-model Chevy 350 V8 and decide to rebuild it into something with a bit more teeth. With the help of a more experienced engine builder, they spend about a year working on the block and heads and finally get a chance to test it on a dynamometer. When all is said and done, they manage to add 110 hp and 115 lb.-ft. of torque to the 20-year-old motor.
Yeah, it’s a common tale — except that this engine build took place at Brighton High School in Brighton, MI, and was handled by three teenagers who had never rebuilt an engine before.
“I’ve tinkered with go kart motors before, but I’d never actually built an engine, so when Mr. Roberts asked me one day if I’d like to try it, it seemed like a great idea,” says senior Dylan Marsh.
Rocky Roberts, automotive instructor for Brighton High School, leads a program that has gone from the verge of extinction to arguably one of the most respected in the State of Michigan in less than three years. With more than 130 participants each year, the program has caught the attention of leading manufacturers and suppliers to the automotive aftermarket.
“I met Rocky when he was at another school in the county,” explains John Hodges of Go Power Systems. “When he took the job of automotive instructor at Brighton, he asked if we had a dyno package we could offer because he planned to reinvigorate the school’s auto shop program.”
His plan was ambitious, Roberts admits. “The program was struggling and the district was considering closing it. I had the opportunity to submit three different proposals for keeping it open: the minimum that was needed; a moderate program comparable to what other schools were doing; and an aggressive plan to create the best program in the county. To the credit of the school board, and especially member John Conely and Superintendent Greg Gray, they decided to make it the best.”
After nearly a half-million dollar investment in tools, equipment and additional infrastructure improvements, the Brighton Area Schools have a jewel in the educational community and a facility that rivals many of the leading automotive repair operations in the entire country.
Of course, without a committed leadership team and invested student base, even the best equipment will be useless. According to Marsh and Cody Fairall, two of the students who built the LT1/LT4 engine, the dedication to excellence is evident at all levels. In just a few short years, the program has produced kids who have interned with or secured jobs at Ilmor Engineering, General Motors and several other Southern Michigan businesses.
School Board member Conely, who donated the police interceptor engine from a 1995 Chevy Caprice and mentored the build, explains that the students were under a tremendous amount of scrutiny for their first build. “The students document every part during assembly and testing so if they have a failure they can fix it. This is part of what we’re teaching – we do evaluation and testing for durability. We’re not just building these motors to idle,” he says.
“The original motor made 230 hp and 300 lb.-ft. of torque. We increased the stroke to 3.750”, added a forged crank, modified pistons and upgraded lifters among other improvements. Their final exam was shaking the engine loose on the dyno, with full power test runs up to wide-open throttle at 6,500 rpm,” Conely says.
Fairall admitted to being nervous about manning the dyno — and whether the engine would hold together — but the experience was a positive one. “Our final results were 340 hp and 415 lb.-ft. of torque,” he says.
“They worked on the engine all semester and we ran it on the dyno the last day of school for seniors,” explains Roberts, “so they were pretty nervous. That day, as all the students came to class, we did a five-minute demo for each of them. There was definitely a buzz throughout the school.”
The dyno cell was designed and constructed in part with the support and assistance of parent volunteers, including Go Power Systems’ Hodges, whose son was a student in Roberts’ classroom prior to the dyno purchase.
“The school got a full-blown GPR Racing package including a D557 standard gas dyno good for 1,000 hp and 10,000 rpm and the GPS 6000 data acquisition and control pack. The electronic throttle and load control allows them to do simulated runs or sit back and work the throttle themselves,” Hodges says. “Students are able to get real-world experience like they can’t find at any other high school.”
The dyno uses a closed-loop water system with a 1,000-gallon tank in the lab’s mezzanine and 100-gallon catch tank outside the dyno cell. Water is pumped between the tanks and through the dyno. “We’re recirculating the water so that the school isn’t using the city water supply or a well,” Hodges explains.
Roberts has set the bar at Brighton extremely high, according to the school board members, and everyone in the county is trying to keep up. The program conforms with NATEF standards and students are trusted with top-shelf tools and equipment from their first day in the shop.
It’s not only high school students who are impressed with the efforts of the Brighton High School instructors. Area middle school students are invited to participate in a program and the school partners with General Motors in a program that begins at the first-grade level.
“I give all the credit for this program’s success on the teachers’ shoulders,” says Conely. “They’ve had to fight the battles to get where they are and I congratulate them.”
Dignitaries from General Motors, Toyota, Ilmor and McLaren have toured the facility and Hodges says he takes potential customers through the school to see what can be done. In addition, the program causes envy in the hearts of many people on regular basis.
“I’ll admit that a lot of dads who come to parent-teacher conferences say they want to come back to school and go through our program,” says Roberts.
If one of the most recognizable hosts of one of the most popular automotive-based reality TV shows came calling and asked you to build a blown big block to squeeze into a vintage collector car to help celebrate the history of an iconic toy, would you blink?
For Jammie Wells, it’s just another day in the shop.
Richard Rawlings, owner of the Gas Monkey Garage in Dallas and host of “Fast N’ Loud,” a reality television series on the Discovery Channel, was given the opportunity to build a replica 1968 Corvette to celebrate the Hot Wheels Sweet 16, the first series of toy cars produced by Mattel in 1968. He immediately had visions of a blown big block engine to power the classic, and he called on WCH Racing Engines in Midlothian, TX to build it.
It wasn’t Wells’ first experience with building for the television series, and this engine, based on the ’68 Corvette’s original 427 big block, developed into a real beast. Chromed, blown and downright nasty, the engine in the gold Midas Monkey pumps nearly 700 horses through a Weiand Supercharger, twin Holley four-barrel carburetors and custom headers. Wells says the engine could be even more powerful than it is – but this is a reminder that “reality” doesn’t necessarily mean “real.”
Wells says he’s worked with the Gas Monkey gang for four years, although it hasn’t always been a smooth road. “I’d been bugging them to get involved with the show but couldn’t get anywhere with Richard or Aaron Kaufman (the Gas Monkey mechanical genius) until another one of my circle track customers told them about me. One of the first engines we did was the motor in Burt Reynolds’ Trans Am.”
Without throwing anyone under the bus, Wells suggests that the TA and another engine WCH and Gas Monkey did together in the early days were, well, challenges. “We didn’t have our dyno yet, so the engines weren’t broken in the way we would have. I’m really thankful to Richard and Aaron, because they could have easily said, ‘We don’t want to have anything to do with you guys – you guys suck,’ when the reality is different. Since then we’ve done about 15 builds with them.”
To meet the rigorous standards of a TV production (and to ensure that producers can’t manufacture any extra drama) WCH dyno tests every engine it sends out the door on its Stuska TrackMaster engine dyno. “Oh man, I put it through vigorous tests,” Wells says. “I let it sit there and just let it run with a load on it, like you’re going down the highway. Just making sure that when they put it in, there is not a problem. We even change the oil before it goes to them, and put more break-in oil in it. I mean, I make sure I double, triple check everything before they get it now. And since we’ve been doing that, we don’t have any troubles at all. And it has really, really been great.”
In addition to “Fast N’ Loud,” WCH Racing Engines is the go-to engine shop for other Dallas TV series including “Misfit Garage” and “Dallas Car Sharks” and Wells is quick to point out that, despite the allure of dealing with celebrity TV hosts, hanging out in VIP areas at vehicle unveilings and being recognized when he walks into a grocery store, he has to keep his game sharp.
“Here’s where I lose out on these shows,” explains Wells. “It’s when someone like GM gives them a crate motor – they can just call up a dealer and get a motor and transmission complete…for a smoking deal. But here’s where I win: they can’t call that dealer and order up an old Cadillac 500 motor, or an old 430 Buick motor, or a big block blower motor for a ’Vette. They can’t. They’re going to get that from, where else, me.”
As exciting as the TV lifestyle is, Wells says his main business continues to be building engines for the circle track racing community.
“That is our bread and butter. I mean literally, we build at least one dirt track engine every day. There’s no if, ands, or buts about that. In addition, I’m really concentrating right now on Show Car events. I’m trying to increase my exposure for classic engine builds. Engine builds like this ’Vette, street rods and stuff like that. And of course, the LS industry is here.
“The LS engine foundation is just an unbelievable engine base – it’s just phenomenal. They’re cheap horsepower to build for an old classic car, hot rod, even drag racing now. Most of any turbo work we do is with the LS platform. It’s just becoming the thing.”
If Wells sounds like he feels the LS is a double-edged sword, it’s because “cheap” isn’t necessarily a good thing for his marketing plan, so he’s not competing against them. But unlike his concern for crate engines impacting his TV business, he says the racing scene isn’t so fragile.
“Here in Texas, it isn’t like it is up north,” Wells says. “You don’t see nearly as many crate motors here. Here, you may see two out in a field of 28 cars. Up north, I think it’s closer to 50/50. One of the biggest dirt track fads around here right now, is a class called the Factory Stocks. There are no crate motors involved. And that class is just unbelievable. We are building more factory stock engines right now than we do anything else.”
Wells says these race motors are built with inexpensive parts: no forged pistons, no aftermarket rods, no aftermarket cranks. Old school, cast iron or aluminum GM intakes.
“They’re called ‘factory stock’ engines for a reason,” Wells says. “They have a cam lift rule of .450˝. There are guys who may spend $30,000, $40,000, $50,000 on a modified engine who are leaving their modified IMCA programs to go to factory stock. Why? I’m really unclear, with the exception of the fact that there’s a lot of high dollar shows put on just for the factory stocks: $2,000, $3,000, $4,000, even $10,000 shows. You just don’t see that for modifieds anymore. I enjoy it: no crates involved. Not just me, but all engine builders are busy because of it.”
Wells believes that one of his keys to success is the fact that he has a large shop with plenty of equipment, yet he has kept his overhead down.
“I have no overhead,” he says. “Everything’s paid for. I broke myself paying for it, but now I’m relaxed.”
Wells employs four employees in his Midlothian shop including himself: Mike Morphew, engine assembly; Manuel Serda, cylinder heads; and Mark Allen Earl, teardown; and relies on a partnership with EPWI for most of his parts and Ferris Equipment for much of his equipment.
WCH Racing Engines’ machining department includes a Rottler boring bar, Peterson surfacing machine, Bridgeport Mill, Sunnen line hone, cylinder hone and rod hone; Hines balanancer and Stuska dyno. Because he also does significant production cylinder head work, a CNC might be on the horizon, despite Wells’ reluctance to take on overhead.
“Yes, I would love to have a CNC machine. But years ago I thought a dyno was out of my reach, and now I have one. With production cylinder head rebuilding it might make sense,” he says.
In addition to the race and hot rod motors, WCH Racing Engines is active with 5.9L Cummins – though Wells admits the customers are harder to categorize.
“It’s kind of crazy – diesels are different than gas engines. I do more just machine work for diesels, like grinding the crank, prepping the block and selling an engine kit. My diesel customers seem to want to put their own stuff together.”
Wells is also involved in building gasoline engines for toy mud trucks. “These big monster trucks are generally like a big block 454, something with high torque mode. 2015 was the first year I really got my foot in the door with these guys – we’re talking trucks are hauled with 18 wheelers, not streetable stuff.”
With customers driving everything from a ’50 Cadillac to the guy with a turbo diesel truck to a circle track race engine, Wells depends on social networks to get his name out. That means word of mouth as well and electronic media.
“When I first started I spent lots of money in the yellow pages; but really, social media is huge with engines. When’s the last time somebody picked up a phone book? I’ve got a lot on Facebook. You could look up our shop address, our phone number. On our like page I even throw out pricing on new packages and stuff for circle track packages,” Wells says.
Wells cautions that relying on social media can be great as long as you watch out for backlash. “You also have the chance of having things go wrong on Facebook, so you really have to watch what people are saying about you. There’s no doubt about that. Social media is absolutely crazy. Holy cow, you’ve got to be careful with it. Especially when you get popular – you really find haters, there’s no doubt about that.”
Growing up in the automotive industry (his father owned salvage yards in Grand Prairie, TX), Wells had an early attraction to the mechanical industries. “I worked in a brake and alignment shop, and next door to us was the guy who ran a shop called Texas Cylinder Heads. Wayne Wallace – his nickname was Moose – was the owner, and at lunch every day, and in the afternoons, I would go over and watch him put heads together, do port work, screw in studs and guide plates. He did a lot of local circle track cylinder heads,” he recalls.
“So somewhere around 20 years ago, after working for a small engine shop in Cedar Hill, TX and then a large cylinder head production shop, I bought a valve grinder and a jet washer and started by myself in a little barn,” Wells says. “And because it wasn’t really a presentable place, I picked up and delivered everything.”
Wells says he’d go to salvage yards and say “’You ought to rebuild these different heads and put them on your shelf.’ If it was high failure cylinder head at the time, we’d bring it back, prepare it, fix it, and I’d deliver for them. But those salvage yards, if they didn’t have a head the customer needed, would just send them over here. There were some embarrassing times because the shop was horrible! I didn’t want anybody there! I was fortunate enough to be able to buy this property and build the first part of the building.”
Success begets success, and Wells began to add on to his business; first came a core storage building, then an expanded teardown and cleaning area, then a custom dyno room, and finally an expanded assembly area. Next up? Wells has his sights set on a chassis dyno.
The Midas Monkey
Wells says that working with customers such as Gas Monkey sometimes means he doesn’t have much input in parts selection. Certain companies may have advertising agreements with the shops and their parts need prominent placement in a build. In some cases, boxes of parts will show up at his shop and he’ll need to figure out how to make them work. Luckily, if they’re not right for the application, he makes his own parts selection.
In the case of the 1968 Corvette, Wells says the supercharger and carburetors sat on top of an Alkydigger spacer. Inside, the motor has Comp cams and lifters; CP-Carrillo Bullet pistons, a Scat crankshaft and forged I-beam connecting rods; Manley valves; King engine bearings; Melling oil pump; Kevco oil pan; Engine Pro billet timing set and ARP bolts.
“With this one we used bolts,” Wells says. “They didn’t want us to use the studs because studs will sometimes bump into the headers, and since Aaron was custom-fabricating the headers from scratch, he already had enough troubles and didn’t want to have to deal with studs.”
The configuration of this engine required Wells to run three different break-in procedures on the dyno. “We couldn’t order a blower belt until we knew exactly how tall the spacer was going to be,” he says. “We ran it first with just the carburetors, then we ran it with the blower and finally with the spacer in place. Final output was just shy of 700 horespower.”
So What’s Next?
Although he admits he didn’t get into this business to be a TV star, Jammie Wells says he plans to continue looking for opportunities to partner with celebrities. “Again, on the business side of it, this is not what I headed out to do. But now I’m all into it and I want to nail all of these other shows including ‘Street Outlaws.’ We’re talking 700-800 cubic inch motors.”
And that celebrity is a great business tool for the rest of his business and allows him to be an advocate for the industry.
“You know, I get calls from our local high school – people there are interested in the industry. Matter of fact, I’ve even gotten some emails just asking me about the industry. And I think that the only reason they ever called us is because they saw us on TV. ‘Hey, what’s it like in your industry? What’s it like owning a shop? Is there any money to be made?” Wells says.
While it looks glamorous on TV, Wells says he wants to be sure the next generation understands the opportunities that exist.
“I wonder who’s going to be putting engines together in my shop in 15 years? Because I have no intentions on shutting my doors any time soon. I’ll probably do this until the day I pass. And I need the younger generation that wants to help do it!”
Turbochargers are used to enhance an engine’s performance and optimize combustion. To achieve good and complete combustion in the engine, a mixture ratio of 2.2 lbs. fuel and approximately 33 lbs. air is necessary (stoichiometric fuel ratio). During turbocharging, the density of the intake air is elevated and the air volume increased.
The volumetric efficiency and thus the efficiency of the combustion engine are significantly improved by means of turbocharging. In addition, the torque can be increased considerably, which enhances performance. The turbocharged engine with the same power output as a naturally aspirated engine can therefore be designed with a smaller displacement and lower weight.
The core of the turbocharger is the rotating assembly, consisting of the turbine wheel with shaft and impeller. The turbine wheel is located on the exhaust side. It is firmly connected to the shaft through friction welding or laser welding. The impeller is mounted on the other end of the rotor shaft, generally with a screw connection.
The exhaust flow from the engine is directed through the turbine, which leads to a rapid rotational movement of the turbine wheel, subsequently driving the impeller. The turbine speed depends on the design and exhaust volume. In small turbochargers, the rotating assembly reaches speeds up to 300,000 RPM. In order not to destroy the turbocharger and engine, the maximum charge air pressure is usually limited by boost pressure regulation.
This information is found in “Turbocharger: Damage Profiles, Causes and Prevention,” a training manual from Mahle Aftermarket (www.mahle-aftermarket.com).
Inadequate lubrication is one of the most frequent causes for turbochargers to fail. If the turbocharger is not sufficiently supplied with oil, its very high speeds will cause damage within a very short time.
What To Look For:
• The impeller and turbine wheel can strike the turbocharger housing on account of bearing damage. This can be recognized from wear marks on the housing.
• If the turbocharger boost pressure is too low, the engine will not perform properly: the rotating assembly no longer reaches the maximum speed and can no longer build up the full boost pressure as a result. The reason for this is the mixed friction caused by the inadequate lubrication.
• The exhaust system emits black smoke. These are the effects of the engine not being supplied with enough air and a correspondingly too rich fuel-air mixture.
• The shaft shank exhibits clear discoloration caused by friction due to inadequate lubrication and the resultant high temperatures between the shaft and the bearings. If the temperature exceeds a certain level, the bearing material will become deposited on the shaft, the bushing might become completely fused to the shaft, or the shaft can even burn out and break.
• If bushings that are permanently incorporated in the bearing housing become fused to the shaft, the bushings might turn out of position.
• The shaft might suddenly become blocked in the bearing housing due to the mixed friction. If the rotating assembly is suddenly blocked, the locking nut of the impeller can become loose.
• The rotating assembly can exhibit a large imbalance owing to the contact with the housing, which might result in the radial bearing breaking.
• Due to incorrect oil or heat soak, the bearing housing can become carbonized.
• The radial bearings have fretted.
• The axial bearing exhibits fretting marks or carbon deposits.
• Knocked-out bearings can cause too great a wobble of the shaft, causing the bearing collar to also be damaged.
Why It Happens:
• The oil level in the engine is generally too low. As a result, not only the engine, but also the turbocharger, receives an inadequate oil lubrication and oil cooling.
• If the oil used is not sufficiently temperature-resistant, the oil supply line of the turbocharger and the oil bores in the bearing housing of the turbocharger can become carbonized.
• If the engine was turned off while hot, the oil supply line can become carbonized, which means the turbocharger is no longer supplied with enough oil.
• If a cold engine was brought to high speeds immediately after the start, there is a risk that the oil supply in the turbocharger is not yet sufficient and hence the oil film in the turbocharger tears off.
• Foreign substances in the oil circuit, such as dirt or sealing residues, may clog the oil supply line of the turbocharger and/or the turbo’s bearing housing.
• If the viscosity of the oil is too high, the oil transport to the bearing points is delayed, which means the timely oil supply of the turbocharger is not ensured, which can lead to mixed friction
• If the engine is operated with biodiesel or vegetable oil, there is a risk of the engine oil gelling.
• The cross section of the bearing housing supply bore might be reduced either through an incorrect flange seal or by a liquid sealant.
Dirt, soot, fuel, water, combustion residues, or metal abrasion can contaminate the oil. Even the smallest particles in the oil can cause serious damage to the turbocharger due to its extremely high speeds.
What To Look For:
• The smallest foreign substances in the oil cause grooves in the bushings. The piston rings in the turbocharger can undergo serious wear. As worn piston rings can no longer adequately seal the turbocharger, the oil enters the turbine side, which can be discerned by increased oil consumption.
• The bearing play of the rotating assembly increases due to the worn bushings. This leads to wobbling movements and causes the turbine wheel or impeller to come into contact with the housing. The shaft might subsequently break off.
• The bearing collar, i.e. the thrust washer of the axial bearing, exhibits grooves.
• Grooves or fretting marks are discernible in the axial bearing.
• Due to a blocked oil return line, the oil in the turbocharger can no longer flow off and is instead forced out to the compressor and turbine side. On the turbine side, the oil might then burn onto the shaft and coke. Owing to the oil carbon layer, the bearing housing and the piston rings might be significantly worn off as a consequence.
• The shaft of the turbocharger shows clear signs of wear at the bearing points.
Why It Happens:
• If the maintenance intervals are exceeded, the oil filter can no longer filter enough dirt out of the oil.
• If the cylinder head gasket or the oil cooler is leaking, water will enter the oil circuit and dilute the oil. Its carrying capacity is thus reduced.
• If the engine was repaired, but not properly cleaned before assembly, dirt will be in the engine even before putting it into operation for the first time.
• If the engine is subject to considerable wear, the mostly metallic wear debris also finds its way into the turbocharger via the oil circuit.
• If combustion faults occur in the engine, non-combusted fuel can end up in the oil. The carrying capacity of the oil is reduced by this dilution.
If the engine shows signs of increased oil consumption and emits blue smoke, you must check the turbocharger as a culprit. But remember, oil is forced out of the housing from a turbocharger only if there’s a problem.
What To Look For:
• Oil is forced out of the turbine or compressor side of the turbocharger.
• Blue smoke is emitted from the exhaust system.
• Engine oil has accumulated in the intake section and charge air cooler.
• Engine power loss.
• Uncontrolled overspeeds resulting in the engine “rising” due to the engine oil accumulating in the charge air cooler, which is blown into the intake of the engine and combusted.
• The guide vanes might be coked in a VTG turbocharger.
Why It Happens:
• If the oil return line of the turbocharger is clogged or constricted by a kink, the oil can no longer flow out of the turbocharger (Fig. B). A possible cause for clogged oil return lines is the coking of the return line, which might be due to missing heat shields, a poorly routed return line, heat soak, inadequate oil quality, or the use of liquid sealants. As the turbocharger is still supplied with oil from the engine circuit, the oil then escapes to the turbine or compressor.
• If the engine is supplied with too much oil, the oil can no longer flow back out of the oil return line into the oil pan (Fig. C). The crankshaft also splashes up the oil. This results in the oil foaming, which forms an additional barrier for the returning oil from the turbocharger (Fig. D).
• If the pressure in the crankcase is too high (Fig. E & F) this pressure will also be transferred to the oil return line. The oil drainage from the turbocharger is thus hindered, and the oil escapes from the turbine or compressor.
Remember, your customers’ oil change habits may impact more than just their engine. Be sure to check their turbo during an engine rebuild.