Thread: 4 year old rebuild in Corvette - now tapping or knocking...leaking oil

Tweet

Isn't there an oil additive to address the zinc and phosphorus issue?

you can get that tappet out the dist hole -to check it out before you go further

Originally Posted by firebird77clone

Isn't there an oil additive to address the zinc and phosphorus issue?

Yes, one can add ZDDP, but many don't realize that having too much zinc and/or phosphorus can bad too. I'd strongly recommend using a properly formulated oil, Gibbs or Penn's for example, and let the chemists handle the chemistry.

so I guess you don't want to answer my suggestion that you can get #8 out the dist hole? and or the comment about shorting out the plugs to see if noise changes????


I've seen many errors in assembly where there was a noise and the opurtunity to diagnose the source wasn't looked at fully and the noise remained after the rebuild------

Your noise and conditions shout at lifter/cam shaft but there ar other places it could be------

no8, back of block--------how about loose converter bolts???? starter nose gear??? could even be broken crank from hammering on the harmonic dampner--------just sayin----check the damn lifter-measure the cam lift on different lobes, etc

Lol! That's tell em Jerry!

wow...I was working on it

wouldn't come out without taking off intake. To the naked eye, the lifter looks ok, no wear marks anywhere on it. Guess it could be failing internally though and not oiling.

I'll measure lift against other lifters that are good and see if I can see something amiss with the cam lobe.

Had this happen years ago, I had a lifter ticking I would retighten it and it would start again, it ended up that one of the pressed in rocker studs was pulling out with the higher valve spring pressure and bigger cam lobes, ended up having to put in screw in studs. Not that this is your problem but "This happened too me"! Check and see if the stud length on the rocker nuts protrude all about the same and ones not lifting. Also Welcome!

while you have intake off spin motor on starter and look for oil in the lifter hole----
by the way, you didn't put any restrictors in the galleys did you??

by hard to get out, does that mean that you had to pull it hard?????like bottom edge messed up?

Does bottom face of lifter have a radiusd face? cam lobe should just be shiny on back edge of lobe and not be real shiny on top of lobe nose

Originally Posted by Matthyj

Had this happen years ago, I had a lifter ticking I would retighten it and it would start again, it ended up that one of the pressed in rocker studs was pulling out with the higher valve spring pressure and bigger cam lobes, ended up having to put in screw in studs. Not that this is your problem but "This happened too me"! Check and see if the stud length on the rocker nuts protrude all about the same and ones not lifting. Also Welcome!

Matt's suggestion is great! I had forgotten, but I've seen that before, too, where a rocker stud was pulling out of the head with the dynamic loading and higher spring pressures. Adjust it, and a few days it's ticking again. Pinning the studs, or better yet, threading the head for screw in studs fixed it!

no...not "hard" to pull out. Was difficult to get to. Lifter slide out nice. Literally all the faces, edges and sides of lifter have no markings whatsoever. These are flat tappet hydraulics, so the face is shiny and flat...no grooves or indentions.

Didn't put any extra restrictors or anything in galley. There was oil in the lifter hole...though I don't know if it was enough. It slide out will the same force as the #8 intake (I took out for reference).

Rocker studs look the same length as the others....they are threaded if I remember right as these are Edelbrock Performer Series heads and I think they screwed in to set them. They look visually the same height and nut goes on rocker and looks the same amount of travel as the others.

Possible broken spring in the lifter?

That's what I'm wondering....if the internals of the lifter are damaged. That would account for the rocker not oiling.

Push Rod was turning though, so I'm hoping the lobe is ok. Still going to take oil filter apart and check to see if I can see metal. Didn't see any obvious flakes when I drained it.

I can still get these same lifters (Edelbrock) from Summit Racing, so I could get one, install it, and break it in....see if that fixes it. Getting the cam out of a Corvette is near impossible without pulling the engine. I do remember that

Pull the hood and radiator, raise the front of the motor and lower the tranny. Ask me how I know...

I would almost bet something got into it and plugged it up, May account for the high oil pressure you had for awhile. You'll probably find the rest of what ever past through in the oil filter. They used to make a cleaner for hydraulic lifters that you added to the oil. Might want to look into it.

Ordered a lifter...while I'm waiting for it, I'll get into the oil filter and examine for metal or other crud.

If it's still tapping after new lifter, cam may be messed up.

I'll keep you posted. Thanks to everyone for the help...