I'm looking at a "dream" truck for me... '89 W350 dually 4x4 5sp with a pto dump. 149k, salvage title but looking very dapper, no rust, $7K, etc. etc. Sound like a good deal? Anyway, the REAL question is... this truck has a definite pop, or knock in its cycle, mixing in with the rumble of the engine... much (10 db??) louder than my truck now. What could this signify? Any input appreciated,
Mike

 

Bad injector maybe?

Heck I dunno. Could be a lot of things I suppose. Sorry I can't be of much help, but I did give ya a free BTT!

Good luck!

 

Just not enough information. From the description it could be as simple as a bad exhaust manifold gasket, or a bad injector, or as bad as a bad rod bearing.

Best to find out for sure before buying. Maybe you've got a gearhead buddy that can go listen.

John

 

Heavy knock or a tap? Idle rough or smooth? Can you hear it in the exhaust or intake? Does it under load or just at idle/overrun?

 

My 12v makes a lot of racket at float on the road, almost sounds like a knock. None at idle, have to listen for it under power. Carbon will do it as well as injectors. Dodges are known for exhaust gasket leaks.

 

Most 1st generation Cummins have a quiet subtle knock at an idle. Drove me crazy when I first got mine. Took it to Cummins Northwest three times before the service manager finally told me that it may have been a little piston slap at the lower part of the stroke. He said it was very common and that they and that it was nothing that would stop the engines from running 250-350k. They run at such a low rpm that isnt even close to a gas engine. Now if its working harder, (Dyno pulling, Hard daily work, sled pulling) the subtle noise may be a little more pronounced from the obvious strain on the rotating assembly.