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Discussion Starter #1
Wondering if anyone on here could give me any input on my R33 GTR V-spec.

The car has rattle which starts at 2.5krpm and follows it all the way up, but only does it when the engine is not loaded, for example when crusing along and feathering the throttle slightly. Quite a high pitched metallic rattle coming from the engine, you can hear it a tiny bit when its idling hot. If you let it come on boost and accelerate moderatly to hard, there are no funny sounds and everything is fine. A guy who seemed to know alot about skylines had a quick look on Sunday and said it seems like possible timing/tappets/valve timer rattling.
Also, when I take her out once the oil has warmed up it makes full boost fine and has its normal power. however 10 mins later when its been running a bit more, it no longer makes full boost and seems to lose alot of its power.. no other symptoms.
The Oil temperature sits just about 70c and the pressure settles between 3 and 4 bar which is perfect.. Its having its timing etc checked this week but im wondering if anyone on here has any ideas... The car is not burning oil, no black smoke from anywhere nothing obviously knackered at all.. any thoughts would be much appreciated! :)
 

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grex

def sounds like the valve train clearances need adjustment. does it have aftermarket cams at all? (sometimes cams get changes and the shims don't). what oil are you running?

Also, I have a friend that had that boost issue as well, but once an aftermarket EBC was installed it went. we checked all the sensors, as it only did it once warm (initially it would boost hard, then drop off.....) thought it could have been an error code causing the ecu to take over. don't know. do you have pod air filters? if so, make sure you have a cold air feed, as we fitted a boxed divider for his when we installed the new EBC.
 

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Discussion Starter #4
Oil is good.
The car has the standard airbox, and standard ECU as far as i'm aware.. I havn't reset the ECU yet.
There are no engine lights or other obvious symptoms associated with this.
 

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I had similar symptons on my R32 GTR. I stripped the engine and found it to be the big ends needing replacing.
 

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Definately worn big ends - sorry.
As the oil warms it thins out, at light load the clearance is too much to support the hydradynamic wedge that stops metal to metal contact and you get the death rattle. On boost the rod is loaded so much that the forces involved tend to stop the rattle, but you will be still getting metal to metal contact. The performance drops off because the knock sensors hear the rattle as detonation and retard the ignition. I had it on a S14 200SX, couldn't be bothered to fix it(because I hated the car) and put a rod through the block. Every rattle you hear is the crank journal trying to tap it's way out of the big end bearing, distorting the b/e cap and stressing the rod bolts. INHO get it fixed asap.
 

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Discussion Starter #8 (Edited)
Grex said:
hmm.. if the knock sensors were detecting the rattle, wouldn't I get the engine warning light?
When you say worn big ends, you mean the bottom end bearings are gone which is why the rattle is occuring as the tolerance is no longer 100% perfect?

Also, I thought if a big end dies its an instant pull over job and the noise you get is a very loud banging.. :confused:
 

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There is no warning light for knock with std ecu, only with Power FC ECU. If you have a power FC ecu then it doesn't have a retard on knock feature.
Yes, worn big ends means the clearances are out of servicable limits.
 

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Discussion Starter #10
Could it not be a case of the tappets need adjusting and its retarding the timing because of that?
Someone who knows skylines has already looked and said its nothing to do with bottom end, as when the bottom end goes.... its game over... am I wrong..
 
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