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Clicking Noise, Low Throttle, High Rpm

CEF33Y

By CEF33Y,
in Engines & Forced Induction

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CEF33Y Experienced

CEF33Y

Posted
Posted

Hey guys,

I've got an issue with my RB20DET.

When I let it rev out with the throttle only just open, (so no where near boost) around 4500- 5000rpm I am getting a clicking noise that dead set sounds like the engine fan hitting something.

The fan has around 3mm of clearance with the harmonic balancer, assumed this would be ok as the fan flex's forward when pulling air through yes?

Radial clearance to the shroud is fine, as I'm using a SR fan (they are smaller).

The noise I think is still there under full throttle, i just can't hear it.

Dont think the noise was there before I did the mods (highflow, nistune, profec b) and had it tuned.

Im running a profec b boost controller, found one thread talking about the solenoid clicking, but if I'm on low throttle % and not on boost the solenoid shouldnt be working? Will unplug on way home today to rule it out.

Its probably due for a timing belt in 10 000 km, although doubt anything in there could make that noise. Maybe?

So before I pull the fan off to rule it out, any other ideas?

Cheers

GTSBoy Grand Master

GTSBoy

Posted
Posted

All sorts of stuff at the front of the engine could make noise. Water pump or alternator bearings. Any of the belts. Even the air-con solenoid pulling in. If it were the fan blades hitting anything at high rpm, I wouldn't expect a clicking noise so much as a continuous high pitched noise or chatter at the very least. I wore a hole through my fan shroud without ever noticing any noise. The Profec's solenoid will be completely inaudible when working (against the background noise).

CEF33Y Experienced

CEF33Y

Posted
  • Author
Posted

Thanks for the reply,

Think i'll just bring the timing belt change forward and have a good look around,

Oh and its only when the thottle is open, if I let the revs fall from high rpm there is no noise. Doesnt really do it in 1st gear. Noticeable in 2nd and 3rd.

No air con fitted.

Will have a closer look on the weekend.

CEF33Y Experienced

CEF33Y

Posted
  • Author
Posted

So, found the issue.

Pulled the fan shround off, some light evidence of the fan contacting the bottom of the shroud.

Put it back together and measured, and there is 12mm clearance from fan to shroud at the bottom, must be a combination of fan flexing and engine moving around, seriously thought that would be enough room, but guess not.

Ran with no shroud for the moment and noise is gone, car ran cooler too, but it is mainly freeway driving.

Will mod the shroud before I put it back on.

Here was I thinking my RB20 had some serious issue, haha should have known better.

Blackkers Experienced

Blackkers

Posted
Posted

Does the engine really flap around? I would have thought that to be plenty of clearance. maybe take a look at your engine mounts next time your under there.

The GTR I recently pulled an engine out of had no symptoms whatsoever of dead mounts. but one was completely sheared in 2 pieces...

GTSBoy Grand Master

GTSBoy

Posted
Posted

The engine certainly does move around a bit, and more to the point, when the fan is spinning fast it can make the shroud move around a fair bit too. If the radiator mouts are loose the radiator can move towards the engine by 7-8mm! In my car I have jammed some vacuum hose in around the upper radiator pins to hold it more firmly, because the original rubbers allow a bit too much movement.

CEF33Y Experienced

CEF33Y

Posted
  • Author
Posted

The radiator is mounted pretty tight, I made my own bushes out of a nylon material.

The shroud is bolted at the top and cable tied (firmly) at the bottom, tbh I can't see that pulling back but its a possibility.

Engine mounts are good.

Also, the wear marks on the shroud are from the front of the fan, not side to side like engine mounts would suggest,

Anyways, I'll will just trim the shroud a bit more, should be ok.

Glad its not anything worse, going in for a touch up tune soon, dont want to hold that up.

89CAL Grand Master

89CAL

Posted
Posted

If it were me (and yes I know it might just be me), I'd want to find out where the movement is and fix it. You may mask the shroud hitting now, and thats all well and good, but the movement may cause a serious problem later on down the track. If its getting dyno tuned I would look at it on the dyno

As above, I had my exhaust side engine mount split in two, never realised this till I pulled the engine out and half the engine mount remained in the car. As far as I was concerned, everything was good

CEF33Y Experienced

CEF33Y

Posted
  • Author
Posted

Yeah, when I give it a service before the dyno I'll confirm the engine mounts are good.

I think the issue is i'm using a sr fan where a rb one should be, and I have a 50mm radiator, so things are not fitting like the factory intended.

Im going to try and measure the fan deflection too, just to confirm how much its moving forward.

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