'98 5.0 cold engine knock

MikesSierra · April 8, 2002

Hello,

I'm new to this board and I have a question. I recently bought a used '98 Sierra (the "square" classic version). The truck has the 5.0L engine with 49K miles and it has recently begun to exhibit a cold engine knock that will disappear as the engine reaches normal operating tempurature. It is most noticeable when the engine is started after sitting overnight; it will also knock a bit if the truck has sat for about 3 or 4 hours (the engine has cooled some but still a little warm).

I have read many of the postings regarding the main bearings and the loose clearances the factory used on this series of engines (for this year and others apparently). I have also read some of the TSB's (for '98) that describe a cold "rod knock" that will fade as the engine warms.

Collectively, what can you tell me about this situation? Is this a common problem with these engines and is it a serious situation that will worsen over time? Realistically, what can be done about this? Has anyone had similar problems with this engine and what did you do about it?

Thanks for wading through my rather long post and I appreciate any info or advice you care to post.

Mike

'98 Sierra

Stepside Z · April 8, 2002

Mike,

I cannot help you with your problem but I do want to welcome you to the forum.

hilly · April 9, 2002

Hi i also have a 98 sierra 5.0 i have also noticed a slight knock during cold starts,it only last a couple of minutes then is gone.the truck has 120.000 kilometers and runs fine.Apparently from what i`ve heard on some news groups newer models ie after the model change in 99 the problem is very bad they refer to it as piston slap there has been very extensive coverage on this and gm is denying there is a problem.I think concerning our trucks [98`s] they are just a little noisy till the oil loosens up and circulates better hopefully not a problem.Larry

MikesSierra · April 9, 2002

hilly,

thanks for the post. the knock in my engine lasts until the engine is fully warm; once warm, it doesn't knock anymore.

I think it is pretty pathetic that GM can't build a decent engine, especially a V-8. Everything today is so tweaked and built to minimal standards as far as durability. There's no excuse for such sloppy and careless work....I guess it's time to go back to the imports :-(.

Mike