| Author |
 Topic  |
|
|
hardybusman
Advanced Member
United States
470 Posts |
 Posted - 07/05/2009 : 1:07:06 PM
|
| I've got an 8.2L in a 1990 GMC school bus. its not a turbo engine. At certain rpm's say 1800-2300 its got a whining noise that I cant seem to find. I think its coming from the engine. Idont see any acceseries that are making noise. The bus doesnt idle the greatest, and I'm guessing the rack is out of adjustment? The bus runs good on the road and has good power for a 8.2, I'm just concerned about the noise. Any advise would be greatly appreciated. |
|
|
IBTMech
Top Member
USA
973 Posts |
Posted - 07/05/2009 : 1:22:47 PM
|
| Allison transmission? Those AT545s can let out a considerable whine just before upshifting. |
If it doesn't fit, FORCE it.
If it breaks, well, it needed replacing anyway.
Pullin' wrenches for 45 years. |
 |
|
|
International-9.0
Advanced Member
USA
459 Posts |
Posted - 07/05/2009 : 7:32:52 PM
|
| I've had trouble on both of my buses with a whine sound. On both of them I traced it to the check valve on the Bendix Air dryer. The newer ones seem to have a whine when the air compressor is loaded and pumping air. I assume it's the check ball rapidly moving back and forth. It's never caused me a problem though. If the idle is poor, the engine probably needs a "tune-up." If you plan to keep the bus for a while, I'd do the tune up or pay somebody that knows what they are doing to do it. Those engines have a very low tolerance for the fuel system that is not set right. If the whine is present throughout all 4 gears, I would not suspect the Allison. They usually whine in 1, 1-2 upshift, 2, and 2-3 upshift. |
|
|
|
hardybusman
Advanced Member
United States
470 Posts |
Posted - 07/06/2009 : 4:25:42 PM
|
| No this noise doesnt get loud until 1800-2300 rpm's or around 45-50 mph, and it changes if you revv or ease on the accelerater thats why I think it's in the engine. All detroits have a distinct sound to them but this one is all its own. Auto trans is fine . What am I looking at as far as a tune up? Even the Detroit dealer doesnt want to work on an 8.2L. Thanks for your input!!! |
Mr. Courtney Hardy
|
|
|
|
International-9.0
Advanced Member
USA
459 Posts |
Posted - 07/06/2009 : 7:02:52 PM
|
| Tune-ups are a pretty complicated and time-consuming deal. You can't half do this sort of thing. If you don't get everything just right, it's a waste of time. You'll need a service manual and a "tune-up kit" from detroit. This job requires special tools, but I think they come in that kit. I'm not sure if you can buy that any more or not, but somebody can help you I'm sure. I have never done a tune-up, but I've read about it in the service manual I have. It's time-consuming for sure, but not that complicated. |
|
|
|
hardybusman
Advanced Member
United States
470 Posts |
Posted - 07/07/2009 : 2:40:37 PM
|
| Probably gonna run her 'till she quits. Its been a real good bus but the GMC is outdated and getting hard to find parts anyway. Thanks again for your time and hope you get your brake issue taken care of. |
Mr. Courtney Hardy
|
|
|
| |
Topic |
|
8.2L making strange noise
