Theres a knocking at 2k RPM on a 3.2, what could it be?

[SHeepsclOthing]

I went to the junkyard today to start up an SHO I found. Its a 94 with the 3.2. It starts right up, revs clean, and sounds strong, but if I hold the revs at 2k, it knocks. Only at a steady RPM does it knock. If I rev up to, through, and past 2k, it doesnt do it. What does this sound like it could be. And would it be worth tearing down the engine and fixing it? It has some miles on it...190k

 

[SHeepsclOthing]

Sorry about that, didnt mean to post it in the Performance section.

 

[SHOtimer]

Well, you might be able to squeeze some more miles out of it if you want to risk it. It could be cam chain tensioners or rod bearings. If it is the bearings you could replace them and see how far the motor will go, but the crank has already been beaten up so who knows how far it will go. If it is the tensioners then you could replace those (I would still check the RB's) and see what it does then. Regardless that is a highmileage motor with no history, I would be wary.


Doug

 

[SHOZ123]

I had a knock on my '93 and it was a cracked rod bearing. Crank was OK. Put new bearings in and drive some more.

 

[SHeepsclOthing]

I plan on replacing the cam chains, tensioners and main and rod bearings anyways. I dont want to do rings right now though. I just really hope that its one of those and not piston slap or something of that sort. Man, Id be one happy dude if it was just a tensioner.

 

[HopefulSHO]

More often than not that knocking will be a bearing/tensioner/chain issue. If you're replacing those you might not have a problem at all.
Then again, it is a SHO.

 

[SHeepsclOthing]

I did some more diagnosing today and its the cylinder closest to the right side headlight, I think thats cyl 5. Its a rod bearing, so Im going to tear the bottom end apart when its out and replace it for sure. The chain and tensioner are silent.

 

[somedude_001]

jump on that thing, you can probably get it cheap as **** if its in a yard.

 

[SHeepsclOthing]

jump on that thing, you can probably get it cheap as **** if its in a yard.

I bought 2 SHOs for 300 bucks. Both run. One needs a chain tensioner (you can hear the chain slapping around) and the other, which Im keeping, needs a rod bearing. Only catch is, he wants the shells back for scrap metal. Anyone need parts lol?

 

[Mr Anonymous]

Two words: Mechanics Stethoscope.

 

[SeanMc]

When my engine overheated, my head bent. You could hear the cam lobe hitting the ihead and it was loud!