I'm having a problem with a loss of power and tapping coming from the engine (sounds like the right head to me). I would like to know what common problems one can expect to see from these two issues, ie. loss of power, knocking/tapping etc. Are there any differences between the two that would distuguish one over the other?

BTW LT1 only has 59,000 miles on a 94 and is all stock.

 

Bad lifter = clicking noise
Bad rod bearing = hammer hitting side of block

Bad lifters could produce a dead cylinder and eventually chew up the cam
Bad rod bearings can be more fun. Can chew up crankshaft or even seize and cause a broken crank, or even fly out the side of the block.

 

IF the rod bearings were only worn and not yet destroyed, would that cause a loss of power? Or is a loss of power more likely to be collapsing lifters. I understand there a Ron of variables here, but I'm trying to get a feel for what direction i need to focus my efforts first to determine a culprit.

Also if the bearings are worn to the point where's there's a little bit of play, am I right in assuming it's just a matter of time before the rod eats the bearings then the crank?

 

WHat tests can I perform to narrow down the search and possibly rule One out?

 

Check the lifters first as it easier and cheaper. Warm engine up to get oil to working temp. Then remove the valve covers (one at a time) and run engine. Place finger on top of each rocker arm while engine is running, the noisy ones will feel as a sharp tap on the finger. This can get messy as oil will spurt out, so be quick about it and only do one side at a time.

 

ok thank you

 

A rod knocking will not always cause a noticable loss of power (until it shoots through the side of the block!). Bad lifters will cause a loss of power since they will not allow the valve to open all the way. You can also get an idea of which hole has the bad lifter with a compression test. it will show compression but not as much as the others do. You will see things like 190, 195, 100, 192 on one head for expample. 3rd hole back is the one with the bad lifter(s) on it.

Massey

 

Well, *update*. I bought and installed brand new lunati lifters. They're OEM replacements. But to my disappointment the noise and power issues are still there. I'm starting to think spun rod bearing(s).