Hi, New to the Forum as well as owning a Chevy. Bought a Really nice 98' Tahoe Z71 4x4 from a guy locally. Has a Fully Rebuilt 4 Bolt Main 350 from the Chevy Dealer. Everything was great until after a week the Trans went out.. put a new trans in. I was driving home from the Mechanics and I started to go up a hill. The engine started knocking or "pinging" really loud and REALLY fast then stopped when I let off the gas and then didnt do it again for a while. Its not all the time and it doesnt do it when its idling or when you start it. Engine only has a few thousand miles on it and I changed the oil when I bought the vehicle. No loss of power. Its not smoking or running rough.. Everything is perfectly fine aside from that random knock. My 02 Mustang GT did the same thing and it turned out to be the timing chain.. Except it knocked ALL the time aside from an idle. I havent pin pointed where the noise is coming from but I got pretty good ears. Sounds like driver side top end. Any help is greatly appreciated. Thanks.

 

First, welcome to the forum, great place for info and you'll get lots of opinions, most of them good hearted. Second, congrads on the purchase. I have a 96 Tahoe with 280K still running hard and just picked up a 99 Hoe with blown head gaskets and cracked heads from over heating, it is in project stage.

Your problem: did it knock or make any of the noises you mentioned before the tranny job? If not I'd almost suspect some one did not tighten teh torque converter bolts to the flexplate(flywheel). Only way to really tell is to drop the flywheel cover plate and take a look. If that is not the issue the tranny mechanics disconnected a sensor wire or something and did not get it hooked back up. I'd almost say its not in the engine if the problem did not exist beforehand. Good lucka nd let us know what you find out and you start diagnosing the issue.

 

Wow, actually didnt think of that. I'll look into it. Tomorrow during the day I'm gonna climb under and take a look at everything. Hes a really good mechanic but everyone makes mistakes and in this case I'm hoping he did haha I reallllly dont have the money for a new motor. Or even to have this one fixed. I could have sworn it was coming from the top end of the engine. But seeing that it only did it a couple times and the engine seems just fine what you said makes more sense. To be safe I bought some Octane Booster and I'm gonna run 93 instead of 87. See if that helps. Prolly shouldn't drive it though huh if something breaks off I could destroy the trans am I right?

 

What sensors or wires should I be looking for and where do I find them? Thanks alot for the help.

 

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