4G93T Head noise..

[MOAN]

I've just had my GSR rebuit.

CP Pistons 20thou over, spool rods, all balanced etc etc

Everything seems perfect except this horrendous head noise. I know the 93's are renowned for lifter rattle so initially we assumed it was that. The builder just replaced the lifters with arftermarket "non-ticking" lifters that I got from Meek. Now, this has quietened it down quite a lot but there is still a significant ticking. Apparently there is no clearance on the lifters whatsoever and there is plenty of oil getting to them. It is a consistent ticking regardless of what temperature the car is at.

The builder and his machinist have racked their brains trying to work out what this ticking is and this is a little beyond my knowledge of engines. They were thinking maybe rocker arms? Someone else also mentioned valve springs to me?

Others have suggested oil additives which I (and the builder) am incredibly reluctant to use on such a fresh engine (1200kms).

Anyway, I guess I'm just chasing some suggestions to go through with him as I just spend a small fortune having it built and I'd really like to eliminate this noise.

Thanks in advance!

 

[nwr31]

since your running cp pistons, i just have to ask, do they have offset gudgeon pins?

if not, it could be piston slap.

 

[MOAN]

I really have no idea about the pins but he assures me it is not that.

 

[lozza]

I really have no idea about the pins but he assures me it is not that.

+1 for pistons. you really need to find out:

1. what is the recommended PTW clearance for CP pistons?
2. what did the machinist actually finish with?
3. When you know 1 and 2 ask other people/machinists what PTW they use with CP and if there was any piston slap with x clearance etc. and how this compares to yours.

 

[nwr31]

and find out what you actually paid for - if the pins are not offset that will be the issue if bore clearance & pin fit is good.

 

[MOAN]

Hmm.. ok well I'll be sure to discuss all of that with the builder. If is it piston slap, what is the general outcome of that? another rebuild?



Other than that, do you guys have any other suggestions for possibilities?

 

[nwr31]

Hmm.. ok well I'll be sure to discuss all of that with the builder. If is it piston slap, what is the general outcome of that? another rebuild?

if it is that, it depends on why its doing it. a member on here said cp pistons dont run pin offset so that would be ther first thing to check, but to really find out you need the pistons out to measure them.

read this link i just found-


http://www.motorcycleproject.com/motorcycle/text/cows-offset.html

 

[MOAN]

His response to piston slap was this:

"they are talking about offset piston pins so that the piston sits slightly skew in the bore to eliminate piston rattle on motors with large piston to bore clearance.

Doesnt apply in your case since the piston to bore clearance is not alot, in fact i dont think your motor has any piston slap at all, even when stone cold."




PS. thanks for that link - I'll have a read

 

[moi]

Do you have aftermarket cam gears? Are the cams dialed in correctly? My engine now "ticks" a lot more after we retarded the exhaust cam quite a few degrees. I believe this is a common trait.

 

[nwr31]

His response to piston slap was this:

"they are talking about offset piston pins so that the piston sits slightly skew in the bore to eliminate piston rattle on motors with large piston to bore clearance.

Doesnt apply in your case since the piston to bore clearance is not alot, in fact i dont think your motor has any piston slap at all, even when stone cold."




PS. thanks for that link - I'll have a read

so is he saying the CP pistons have offset or not? (just interested to know)
cheers

 

[MOAN]

Do you have aftermarket cam gears? Are the cams dialed in correctly? My engine now "ticks" a lot more after we retarded the exhaust cam quite a few degrees. I believe this is a common trait.

Nah stock cam gears..

so is he saying the CP pistons have offset or not? (just interested to know)
cheers

Well, he hasn't said. That response was based on a different thread I showed him not this one. I will ask him though!

 

[BMGTZ]

let me describe the noise for you and see if it is the same as what I am getting.

at idle it is a noise not unlike a noisy set of lifters but with more of a clack than a tick.? When the engine is revved the noise becomes slightly louder the instant the throttle is opened but gets softer when the throttle is held constant?

when driving at cruise...it sounds like lifter tick but as soon as you accelerate it get louder and stays there for the whole time you accelerate.

some would even say it is like a muffle ping/detonation sound.

it is there if you shift down to use engine braking....but gets softer as the engine looses revs.

that is gudgeon noise.....and there is nothing you can do about it.

from what I have been told

all the forged pistons that are special order are made to the same recipe.......as opposed to off the shelf pistons where batch after batch are made and each batch is subject to subtle developmental changes based on customers feed back.

 

[lefty]

Why not take a video and post for all of us?
Probably helps you not having to describe the problem, plus someone here might know or has had this issue, plus then more people will learn/know like me, lol

I had my lifters changed (bought from meek also), and my lifter noise is totally gone.. that was more of a "ticking" sound but would only last a few mins or less until the engine warmed up a bit, so doesn't sound like lifters I guess...

 

[moi]

Hey guys/gals, more information: we had a quick listen to Simone's car, further diagnosis will be required. It is definitely top end noise, not bottom end noise. Does sound like minor lifter noise though. There is a very quick fix though.. buy my evo Simone

 

[caged]

check the oil pressure at the head through the oil pressure sensor fitting. I usually taper and enlarge the oil feed going into the head from the block as it seems to help with 4g93 lifter tick.

 

[khubner1]

another cure for lifter tick is 3g lifters or so im told

 

[MOAN]

Hey guys/gals, more information: we had a quick listen to Simone's car, further diagnosis will be required. It is definitely top end noise, not bottom end noise. Does sound like minor lifter noise though. There is a very quick fix though.. buy my evo Simone

lol moi! swaps?