Ticking Sound On Idle - Rb25

[colourclassic]

My RB25 has developed a ticking sound which appears when the engine is warm and only at idle. Anything above idle and it seems to disappear.

It is *not* the injectors pulsing. In fact it can barely be heard when your head is over the engine.

You can hear it best when listening either below the engine or at the back of the front wheel wells.

I tried using a wooden dowel/long screwdriver stethoscope but couldn't isolate the origin of the sound.

I recorded a short audio clip from below the car which demonstrates the sound:

I first thought sticky lifters or a leaking exhaust gasket, but they would presumably appear worse when cold. This sound only appears when the engine is up to temp.

Ideas?

[Humbla]

Exhaust manifold gasket. :-)

[colourclassic]

If it was exhaust gasket I would have thought it would either be the same regardless of temperature, if anything get better due to metal expansion.

Any other ideas?

[Ben C34]

Exhaust leak.

Maybe from gasket, maybe not.

[Jim.t]

Did u end up figuring out what the noise was cause I have the exact same noise with my rb25?

[Diddle]

G’day, I Have this exact same noise in the video, anyone end up figuring it out? Same issue as originally described and tried everything OP did aswell. Only once warmed up, runs and sounds fine while warming up. Not an exhaust leak, all new gaskets + studs, washers and nuts for manifold and turbo. Also changed oil and filter plus trying different oil viscosities, hasn’t made a difference.  

Leaning towards lifters but due to it being alright on cold start has me baffled.
 

[Diddle]

Bump. Lifters replaced a few months ago and noise persists

[robbo_rb180]

Use to get a similiar noise on s14 with vct would make similiar noise. Could be nosiey VCT?

[Diddle]

VCT is working fine, it’s even difficult to locate the sound with a stethoscope. However definitely audible from under the engine as with OP’s video. Possibly worn bearings but it’s definitely not a knock. The sound can be heard while driving with the window down aswell when passing a barrier or other cars when the sound bounces back. Sounds like a little jingle bell weirdly enough. Any other ideas? 

[myrbgivesmeheadaches]

Sorry for reviving an old post, but I'm having the same hot idle tick issue. Did anyone ever find out what it was? 

I have checked/ replaced

Injectors

Coils

checked Lifter clerance (is at zero)

Checked Cam lobes

Replaced exhaust gasket and studs

Would appreciate any advice this is driving me nuts

 

[GTSBoy]

23 minutes ago, myrbgivesmeheadaches said:

checked Lifter clerance (is at zero)

This seems problematic and unlikely at the same time.

1. Vanilla RB2Xs have hydraulic lifters. They do have "zero" clearance, but only when running with oil pressure inside them. When not running, you should be able to compress them and obtain heaps of clearance.
2. RB26s and Neos have solid lifters. They should have ~0.3mm and ~0.5mm on the inlet and exhaust respectively. If they have zero clearance then bad things are happening. With nothing else being wrong, it would mean that the valves would be held slightly (ever so slightly) open when they are supposed to be closed and it should have all sorts of problems when running, caused by leakage in/out through the valves. Or, zero clearance can indicate severe valve seat recession. None of it is good.

Have you used a piece of hose as a stethoscope to try to localise the noise?

 

[myrbgivesmeheadaches]

Thanks for the reply @GTSBoy this is is a hydraulic lifter engine. Yea right i did not realise the lifters were supposed to be compressible while installed. I could push them down but i had to lean almost my while body weight on them. 

I have never heard of a lifter/ lifters ticking only at hot idle and getting worse the hotter it gets. I have owned a few jdm cars with noisy lifters. This noise is slightly more subtle, it is more of a sharp gentle metalic tic than the solid and more loud tapping I've heard on lifters.

I have used a metal rod, alloy tube, hose and stethoscope and could not find the source of the tick. But it appears to be loudest on the actual engine block behind the exhaust cam gear and next to the oil filter.

I had mate (40 year old mechanic) go over it with me and he couldn't find it either.. 

Could it be a cam seal issue of some sort? 

Cheers

 

[GTSBoy]

1 hour ago, myrbgivesmeheadaches said:

I have never heard of a lifter/ lifters ticking only at hot idle and getting worse the hotter it gets.

Well, hydraulic lifters will get noisy if they are dirty/fouled in some way, and exactly how that manifests will depend on exactly what schmutz is where.

There is a procedure on here somewhere for dismantling and soaking/cleaning them. Replacing them with new is about 50% of the work and about 5% of the money!

[MBS206]

Have you put an aftermarket oil pressure gauge on and verified your oil pressure?

 

Noise being on the block, on exhaust side, how high up the block does it seem to be?

It could be the VCT system getting cranky, especially if it's mainly at idle, and when warm, as that'll be your lowest point for oil pressure. Could be showing that oil passages / VCT solenoid are blocking.

[myrbgivesmeheadaches]

On 01/04/2025 at 5:49 PM, GTSBoy said:

Well, hydraulic lifters will get noisy if they are dirty/fouled in some way, and exactly how that manifests will depend on exactly what schmutz is where.

There is a procedure on here somewhere for dismantling and soaking/cleaning them. Replacing them with new is about 50% of the work and about 5% of the money!

Thanks for the reply mate, Yes I get that schmutz und drek is most likely the cause if it is a lifter, it just seems highly improbable that a colapsed lifter ticks after it warms up and gets better oil flow and is dead quiet at cold idle.. the physics dont add up. Do you know where I can get new lifters from without paying the price of a tomei solid conversion? 

[myrbgivesmeheadaches]

On 01/04/2025 at 9:19 PM, MBS206 said:

Have you put an aftermarket oil pressure gauge on and verified your oil pressure?

 

Noise being on the block, on exhaust side, how high up the block does it seem to be?

It could be the VCT system getting cranky, especially if it's mainly at idle, and when warm, as that'll be your lowest point for oil pressure. Could be showing that oil passages / VCT solenoid are blocking.

Mbs206 yea I have a link ecu which tells me the oil pressure is at 185kpa ish at idle.. it seems to be more on the intake side. I have cleaned out the vct and checked for gunk but there doesn't seem to be any. Externally it's loudest on the drivers side under the car.

[Dose Pipe Sutututu]

6 minutes ago, myrbgivesmeheadaches said:

oil pressure is at 185kpa ish at idle

What oil weight are you using? That oil pressure is a bit concerning 

[myrbgivesmeheadaches]

20 minutes ago, Dose Pipe Sutututu said:

What oil weight are you using? That oil pressure is a bit concerning 

Damn really? 185kpa is like 26psi at 650rpm.. I thought that was ok? Using 10-60 castrol supercar. What should the oil pressure be with that weight oil? 

[GTSBoy]

You typically expect about 100 kPa at idle - 1000 rpm. You're in the region of double that.

[Dose Pipe Sutututu]

3 minutes ago, GTSBoy said:

You typically expect about 100 kPa at idle - 1000 rpm. You're in the region of double that.

That's heaps low tbh

 

42 minutes ago, myrbgivesmeheadaches said:

Damn really? 185kpa is like 26psi at 650rpm.. I thought that was ok? Using 10-60 castrol supercar. What should the oil pressure be with that weight oil? 

Is your oil pump factory?