Knock on start up????!!??

[englishrodder]

Hi There,
My GTR has a knock on start-up that only happens when cold for about 1.5 seconds and then stops. No apparent knocks from the engine or deep sounds (when using stethoscope). Doesnt do this when its been run and then stopped.

Sounds like its only happening until oil pressure gets up. Recently changed oil and filter. Engine has 55k miles and running standard boost (currently on standard ECU not fitted the Middlehurst one yet).
No smoke, doesnt use any significant oil, no sounds once running that I can tell...

Ideas? Should I be worried?

[toddrb30gtr]

Originally Posted by englishrodder

Hi There,
My GTR has a knock on start-up that only happens when cold for about 1.5 seconds and then stops. No apparent knocks from the engine or deep sounds (when using stethoscope). Doesnt do this when its been run and then stopped.

Sounds like its only happening until oil pressure gets up. Recently changed oil and filter. Engine has 55k miles and running standard boost (currently on standard ECU not fitted the Middlehurst one yet).
No smoke, doesnt use any significant oil, no sounds once running that I can tell...

Ideas? Should I be worried?

what grade oil you running mate? and oil filter type? and your probly going to think this is a bit funny but what type of clutch?

[englishrodder]

Hi,
Running Catrol Edge 0-40W with new Nissan filter. Hmm Clutch is a total guess, I bought the car as standard but with investigation looks like it may have been modified in Japan some time before.
Clutch is quite heavy though.....

[lynchy]

That's oil isn't recommended. Generally a 10/50 is used from memory, have a search. Speak to oilman on here he'll sort you out.

[Pikey]

0W will get round the engine quicker than 10W, so I dont think that's his problem!

Does it correspond with the oil pressure light going out? ie - when the noise stops the light goes out?

[David]

Have you fitted a cheapy oil filter which doesnt have a one way valve in it. Allowing the oil to drain back into the sump overnight?

[englishrodder]

Hi All,

It was a proper Nissan Skyline filter from Middlehurst, so should be no problem with the Filter. Oil light goes out near instantly on start up.

Today it did the same thing, so decided to let it war up nicely and then re-start once idled for a while. No knock on start up but sounds like a "delayed" rumble from the rear of the engine.
No smoke or oil burning from the motor, cant feel any DET when driving and boosts all fine....

Seems like I can hear the sound more since adding the HKS dragger and Apexi induction....Running car on 97 oct and using octane booster at each fill up.

Think I may get it checked out just in case! Dont want a massive bill after Ive blown it up! Having never owned a GTR before bit hard to tell what is normal mechanical noise (Normally used to big yank V8's!)
Cheers

[Alan]

OK this may sound silly but I had the same when I fitted my cams, Believe it or not it was my center box of my HKS Hiper exhaust where it had been hit a few on speed bumps the skin had got very thin and pulsed when the car was started causing a deep rumble for a few seconds. This only happened when the exhaust was cold.

So get under the car and touch the center box whilst someone starts the car and if it runbles put pressure on the skin and see if it stops.

Took me 2 weeks to find it and a lot of worrying.

Hope this helps

Best regards Alan

[englishrodder]

Cheers,
Ok Im gonna check, actually I guess it could be that as I hadnt noticed any noise before and the motor pulls really well.
Just fitted the Middlehurst ECU so off for a trial run to see what its like.

Thanks

[leggus]

My mate has a similar issue with his R32, he seems to think upgrading the oil pump will help, my R32 has standard oil pump (as far as i know) yet i dont have this problem.