Across 1. Diagnostic drive by service technician (4,4) 5. Loose-piston noise 9. Term for unevenness in carburetion 10. Term for shuddering clutch action 11. Shifting device in Formula One car 12. A company’s trucks, collectively 14. Removable item with ratchet sound (3,3) 16. Term for washer-equipped wiper (3,3) 19. Serpentine belt ____ pulley 21. Procession of Rose Bowl floats 24. Add air to a tire 25. Hydraulic or ____ valve lifters 26. Uppermost part of camshaft lobe 27. Big name in the coolant-antifreeze biz

Down
1. Hand-file type
2. They’re found below front bumpers (3,4)
3. Where the rubber meets the road
4. Six- or twelve-point toolbox item
6. Brake-shop tool for drum resurfacing
7. Adjective for some 4×4 systems (4,4)
8. Obstruction in muffler or fuel tank
13. System that includes coil, plugs, etc.
15. Item in passenger-restraint system
17. Well-known auto-parts company (1,1,5)
18. Final word in right-side-mirror message
20. Certain turns
22. Succumbs to corrosion
23. No-throttle engine speed