Knocking, possibly from head.

[Syndicate13]

Well I installed a set of FP Cam 1's this past weekend. All timing marks lined up after the motor was turned over by hand. I have been fighting knock issues since then but that is another matter. Today I was trying to tune the car and was getting on it fairly heavily. As I was slowing down I pushed in the clutch and started braking and the car shut off. I turned it back over quickly and made a quick right off the road. I accelerated normally and heard a knocking from the motor around 2500 RPM. It does not make the noise at idle but when revved around 2500 it makes a knocking sound. Under harder acceleration the noise is not present, it's almost intermittent. I plan on pulling the VC tomorrow to check the rockers and lifters but I was wondering if anyone had any insight to what it may be. Thanks for any help.

 

[GSX92AWD]

I feel your pain man, I have the same problem on my 92. I don't think that it's not there on hard acceleration I just think the rpms are moving to fast to hear it. I don't know where to start though I'm actually contemplating buying a new head since the one I bought is a piece of crap and had everything wrong with it.

 

[44pirate]

That's how my rod knock started. Drain the oil and look for flakes. Drop the oil pan look for flakes and check con rods to see if any wiggle. Surely if it is a bearing you will see flakes in the oil or in the pan.

 

[Syndicate13]

Definitely something in the bottom end. Knock goes away when the #3 plug wire is pulled, taking the load off the cylinder. Guy at work says possibly wristpin failure, I would think a spun rod bearing would cause the noise all the time.

 

[GSX92AWD]

I've taken my pan off and didn't see any flakes. If I'm understanding you right syndicate13 I can just unlplug the wires one by one and take it up to 3 grand and if I don't hear the noise on one of the cylinders it is probably a bottom end problem in that cylinder?

 

[Syndicate13]

I've taken my pan off and didn't see any flakes. If I'm understanding you right syndicate13 I can just unlplug the wires one by one and take it up to 3 grand and if I don't hear the noise on one of the cylinders it is probably a bottom end problem in that cylinder?

Pulling the plug wire takes the load off the cylinder. If the noise remains then it's probably something in the head. I think mine is a spun rod bearing, I don't have the time to drop the pan right now so the car will sit until I can get to it.

 

[GSX92AWD]

Interesting I will have to try that once I get back to my car. Thanks for the info. Oh yeah so if it is a rod bearing can you just change it or does it have to go to the machine shop?