I currently drive a 91 Olds Toronado Trofeo with a 3.8L engine and when i start my car when the motors cold, theres a terrible knocking in the motor that lasts for a couple seconds. The knocking is so great that it makes the whole car shake. When i start up and look under the hood it sounds like its coming from the bottom part of the motor near the exhaust manifold. Does anyone have any clue what it could be? Thanks!

mine does the same, its a Lifter.. altho mine does not shake, your's still sounds like it could be a lifter..
-Joe

A lifter would be more of a tick, and the noise would be generated in the top end of the engine, almost as if it were coming out of the valve cover. I would check your motor mounts. Is this knock metallic, or is it more of a clunk of something big? I hate to answer a question with a question, but there are many possibilities.

Andrew

A lifter would be more of a tick, and the noise would be generated in the top end of the engine, almost as if it were coming out of the valve cover. I would check your motor mounts. Is this knock metallic, or is it more of a clunk of something big? I hate to answer a question with a question, but there are many possibilities.

Andrew





It sounds more like a clunking sound, and i also noticed sometimes if i give a little gas in neutral and back off it, it will make a clunking noise

I think it might be a motor mount, but without hearing it, its tough to tell. You might want to get a long screwdriver and have some one rev the engine while you plave the tip on various non rotating parts with your ear up to the end of it. Try the trans bell housing, and watch the engine for excess movement while revving. Hope that helps

Andrew

sorry for giving you the wrong answer, and thanx andrew for clearing that up for me.
-Joe

No problem, since the board doesnt have sound bytes, its hard to diagnose when you cant hear it. Could be anything from a lifter to a rod. But any answer is a mere guess until the actual sound is heard.

Andrew

since its hard for us to tell what it is, id just take it in..
-Joe

or its nothing...it could just be an oil pump problem...

But an oil pump problem is SOMETHING. I would say that if your engine knowck audibly at startup, and if that knock is so great that it makes the entire car shake, then it is most definitely SOMETHING.

Andrew

my friends vehicle had a problem with the oil pump. He knew about the oil pump problem, and chose to ignore it... The car self destructed when the pump finally siezed...