Rb26 Engine Noise Help.

[gtmatt]

Hi, firstly can i say congrats to administrators for giving people like me access to such a great resouce such as this forum.

righto to the problem.

The rb26 in my r32 gtr has developed a knocking noise starting at 2200-2400RPM and increases in noise intensity to 3000RPM.

At idle the engine there is no miss, no noise showing no sign of a fault.

I have changed oil, pulled out the cams, compressed each valve individually and put it all back together to eliminate any issues with cam timing however the noise is still there.

The noise was first noticed after doing several 1/4 mile runs on the g-tec. I had a wideband installed during the runs to ensure mixtures were ok as the engine had been rebuilt about 2000km's before (by myself). The turbo's were running standard boost. There was no noticable noise to indicate a failure, the noise was only noticed when i left to go home.

the noise is a solid noise at 3000 almost sounds like it is in the inlet side of the head.

I havent yet changed the cam timing to ensure it is not valve knock. The engine turns over by hand fine with no noticable issues. On inspection of the cams there was no noticible sign of an issue, aside from a wear mark on no 6 exhaust base circle but checked clearances and was fine.

i have heard big end knock before (the reason for the rebuild) and i dont believe it is the issue.

The list of mods for stage one

- JE forged pistons,

- ARGO rods with arp bolts,

- Jun oil pump,

- Calico coated main and big end bearings,

- Tomeii cams type B and valve springs,

- Tomeii head and manifold gasket set,

- Aftermarket split dumps,

- Garrett GT2560 turb's

- new r33 crank

- head oil restrictor

- tomeii sump baffle

- modded oil return line to sump

- turbo blankets and manifolds heat wraped

- Ross Harmonic balancer

- ARP head and mains studs and bolts

if anyone has come across this issue before and knows what it may be can you please enlighten me as it has me puzzled mostly due to the inconsistancy of starting at 2200 ie a valve knock would be heard at idle, so too would a big end failure. I am maybe thinking it might be an issue with a peice of ancillary equipement on the engine - not explored.

thankyou for any future help.

[gillies2001]

I have an R32 GTR which had a knock about two years ago, at 2000--3500 RPM It sounded pretty bad but hard to believe, turned out to be only the cam belt bearings. Just a thought.

[gtmatt]

I have an R32 GTR which had a knock about two years ago, at 2000--3500 RPM It sounded pretty bad but hard to believe, turned out to be only the cam belt bearings. Just a thought.

Thanks, when you say cam belt bearings, do you mean the cam belt tensioners, i never thought of them being an issue because they are new, but doesnt mean they havent failed i will check it out thanks.

[N1GTR]

Checked gaskets?

[gtmatt]

Checked gaskets?

i havent looked for gasket leakes, what are you thinking might be the issue

[N1GTR]

Blown gasket.

Mine did that last week, the sound was a strange one and sounded like a few other things that have gone bang on my gtr over time, but as soon as it was looked at by the shop they saw the carbon buildup around the front turbo manifold and then it became clear. I couldnt see it cause it happened at night

Its probably not, but doesnt hurt to check and rule out that possibility

[gtmatt]

Blown gasket.

Mine did that last week, the sound was a strange one and sounded like a few other things that have gone bang on my gtr over time, but as soon as it was looked at by the shop they saw the carbon buildup around the front turbo manifold and then it became clear. I couldnt see it cause it happened at night

Its probably not, but doesnt hurt to check and rule out that possibility

thanks its on the list of things to do

[SimonR32]

possibly dropped a valve guide?!?

its a really common problem with rb26 and i see in your mod list they have not been replaced...

[gillies2001]

Yes, the cam belt tensioners . As yours are new i would think its unlikely.

[gtmatt]

possibly dropped a valve guide?!?

its a really common problem with rb26 and i see in your mod list they have not been replaced...

yeah your right i think a head pull is the next step i was trying to avoid it (hence the post and if anything else might be the prob) but have pulled it down as far as having cams out and didnt find anything that was likely to be the issue but because it was so over a year ago that it happened i put it back together to relearn the noise etc, and also rule out some of the simple things.

thanks for the advice