Drivers of some 2004-11 GM trucks with inline engines may complain of a drive belt screech or howl along with a rough idle. In some cases, the check engine light may also be illuminated, with trouble code P0106, P0014 and/or P0017 stored in PCM memory. Two possible causes for the trouble, GM said, are a defective camshaft actuator solenoid or excessive crankshaft end play due to a worn thrust bearing.
Begin your diagnosis by removing the camshaft actuator solenoid. As you can see by the illustration, the solenoid has three grooves with oil feed holes. Groove No. 1 supplies advance pressure to the cam actuator; groove No. 2 supplies pressurized oil from the oil pump; and groove No. 3 supplies retard pressure to the actuator. What isn't obvious in the illustration are the three fine-mesh screens in the grooves that prevent small dirt particles from entering the cam actuator. If any of the screens are clogged or missing, replace the solenoid, change the oil and filter, then start the engine and see if the symptoms are still there.
If the cam actuator solenoid looks good, check the crankshaft end play with a dial indicator. Normal end play should be .004-.015 inch. If it's off by .001 inch or so, don't sweat it. Just replace the cam actuator solenoid, change the oil and filter and you should be done with the fix. If the crankshaft end play is way out of spec, say .050-inch, the thrust bearing is worn. Your only two options are to replace the complete short block or install a new crankshaft and bearings. GM recommends replacing the short block because it will be tough getting out all the thrust bearing material left behind in the engine, which will either damage the new crankshaft and bearings or cause the trouble codes to reset due to the tight tolerances in the cam actuator.
Trucks that are susceptible to the belt noise and rough idle issues are 2004-09 Chevrolet TrailBlazers and Hummer H3s; and 2004-11 Chevy Colorados and GMC Envoys and Canyons.
Some 1998-2000 RAV4 SUVs may illuminate the check engine light and log trouble code P1133 in computer memory. One likely cause for the problems, reports Toyota, is an inactive air/fuel ratio sensor. Installing a new-design sensor, part No. 89467-42030, should resolve the issue immediately.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected]