Hello,just picked up a 98 jimmy slt for my son. 103k on the 4.3 vortec. It is 4wd and a solid truck! To my dissmay it is making an engine noise I didn't notice until I drove it 75 miles home. The jimmy wasn't drivin much the last few months before I bought it. I've had a number of opinions from some local mechanics, most saying if it was a bottom end thing like a rod it wouldn't run as good as it does and I probably wouldn't have made it home. It doesn't make the rattle/clacking noise at idle, but when you take it up to about 2000 and hold it there.I did an oil change and added a quart of Lucas and it quieted down drastically! Been hearing its timing chain or valves? Any ideas would be greatly appreciated! If I can figure out how to post the video of before and after the oil change with the Lucas I will. Thanks in advance!

 

Can you give a more detailed description of the noise? If you don't have a stethoscope handy, placing the point of a long handled screwdriver against various places on the engine and putting the handle firmly against an ear reveals a more specific source of the noise.

 

This, but while you are doing this, make sure you are safe and watch out for pulleys ect and clothing getting pulled into it, or your skin touching it.
(you would think that is common sense but a lot of people have gotten hurt because of that)

 

^^^^^
yup I have a scar on my left wrist from a third degree burn years ago in the shape of a watch band - arked across the pos. battery pole and grounding to the body reaching to get a wrench - things get hot in less than a second

 

Thanks guys,i actually had a mechanic from the dealership i work at "im a painter not a mechanic lol" listen with a stethoscope.His belief is timing chain,while up in the air he said he heard it slightly at the oil pan but not the bottom of the chain cover.He said he hears it at the top of the chain cover and one of the valve covers?? So i'm at a loss,maybe i had too many opinions lol.One seasoned guy says if it was bottom end it wouldn't run as good as it does nor would i have made it home?? Again i did an oil change and added a quart of Lucas and it helped pretty drastically???

 

My best description would be if i take 2 screwdrivers and hit them together rapidly lol!

 

You`ll have to do your home work on this one.Sounds it will take sometime in doing so.Have your son start her up,give a little gas while you chase down the noise.It`s just hard to say what it maybe from the way your describing it.With that amount of miles on her you would think it wouldn`t have any issues.But then again you never know.Go ahead and get a second opinion from another (trust worthy) mechanic if need be.

 

Thanks,really mind boggling! Just brought it home from work and it runs like a top! No CEL either! I've been reding up on spark knock/balance shaft,camshaft sensor?