Ticking/rattling- clutch implicated, I'm perplexed

[zestyfesty]

Hi Guys, hoping those with some expertise can share thoughts -

Engine has 900km on it since a full rebuild, including new clutch kit. We changed to E85 and upgraded (stock frame) turbo. These items aside, it has been a replacement of existing parts (new forged rods/pistons, bolts, bearings etc).

Chassis has 150,000km, standard 5spd gearbox which has never been opened.

Previous rebuild with same mechanic we got 47,000km of road and 3000km of competition use. I treat my car with mechanical sympathy and never abuse it.

These 900km have only been used on metro roads, light use. Since rebuild there has been an 'idle dip' occurring between gearshifts which mechanic was aware of. This appears to have exacerbated over the past couple of months; standing still, disengagement of the clutch (pressing pedal) drops engine idle and can stall occasionally when engine warm. On the move, engine speed drops rapidly between shifts and will stall if shift is slow.
I've wracked my beginner's level mechanical brain over this for a week.

There is a clear rattling/ticking noise with engine running, that wasn't there after engine was first completed. I thought perhaps this was a clutch bearing (pilot or release? causing noise and maybe poor alignment placing load on input shaft) or maybe an input shaft bearing problem. But the ticking increases in frequency with engine speed, suggesting non-transmission, however as explained the transmission is implicated through depressing clutch.
Noise appears to be concentrated at the front of the engine, not bell housing area (although this is not conclusive)
A light press of the clutch will illicit a change in the nature of the noise, and full clutch depression will drop revs 2-300rpm when sitting in neutral idling.
Any thoughts much appreciated (that car is booked in for inspection in 2 weeks)
I'm reluctant to drive it as it doesn't feel right/healthy, and I'm really perplexed.
Clive? Anyone?

I've tried to add youtube links below, bit of a dork with tech, so hope it works.

[https://youtu.be/-vIhbJs-x2I]
[https://youtu.be/0srtMa6RqWg]

Thanks
Jim

[zestyfesty]

https://youtu.be/-vIhbJs-x2I

YouTube (Short URL)

YouTube (Short URL)

[Coggy]

My IV was doing this when I had crankwalk. Revs dropping when the clutch pedal pressed down. I could hear a ticking on mine, which turned out to be the crank reluctor disc eating away at the crank sensor.

Just a thought

[Hedgehog Dodger]

I would check the exhaust turbine housing where the actuator arm is.

I have a rattle on tickover, over run basically when the car is off boost. The flap overtime distorts in the turbine housing and rattles. Common issue on 4 5 and 6 Evos. The 7 onwards had a cap over the top to stop this.

See if the noise is there when the car is under load.

Possible new turbo time

[zestyfesty]

Originally Posted by Hedgehog Dodger

I would check the exhaust turbine housing where the actuator arm is.

I have a rattle on tickover, over run basically when the car is off boost. The flap overtime distorts in the turbine housing and rattles. Common issue on 4 5 and 6 Evos. The 7 onwards had a cap over the top to stop this.

See if the noise is there when the car is under load.

Possible new turbo time

We fitted a brand new turbo and actuator with engine rebuild 900kms ago, so this is unlikely, but thanks.

[Phil2333]

Exhaust manifold gasket leak....causes ticking noises.

[zestyfesty]

Originally Posted by Coggy

My IV was doing this when I had crankwalk. Revs dropping when the clutch pedal pressed down. I could hear a ticking on mine, which turned out to be the crank reluctor disc eating away at the crank sensor.

Just a thought

Thanks for your thought. I dearly hope note. It's a newly built engine.

[plip1953]

My immediate thought was a crankshaft thrust bearing issue.......

[zestyfesty]

Dial gauge indicated end float of .0042".

Engine being removed and rectification being undertaken by engine builders.

Very keen to know what has happened in bottom end, particularly given the new quality parts used.

Thanks for your thoughts all...

[zestyfesty]

meanwhile, I've had more time to become slightly obsessed with my wife's BRZ. Geeze this car is damn delight to drive.

[zestyfesty]

Closure, finally. And the winner from above is...Plip1953

The crank had walked - 0.0045 this time. My mechanic had outsourced the short motor rebuild to a local engine builder who didn't do as he was asked with the rebuild. Whatever they did may or may not have caused the issue. They were asked to inspect, so disassembled and simply returned it in bits. And then hurled abuse when asked help solve the problem. Suffice to say my mechanic has worn all of the financial responsibility for the rebuild these past months and left no stone unturned in ensuring everything was right this time.

So the big call was his decision to upgrade the bottom end to create a 360degree thrust web cradle running through both cradle and block (Apparently very early Evo 4G63s used this design) So tooling had to be made for the machining of the block. This was all done by a highly reputable race engine builder in Melbourne. New crank, bearings etc, and short motor re-assembled.

Meanwhile clutch was sent off to Exedy lab where it was tested and confirmed as working to spec.(Mechanic concerned about possible role of clutch in the end float) They rebuilt the clutch system,new seals for slave and master cylinders, bored and cleaned the cylinders, replaced the fluid. (they were frankly preoccupied with ensuring the clutch system was working exactly as Mitsubishi designed it).

The idle issue was a funny one too (likely linked to the walk, but at same time an independent idle issue was revealed) Mechanic finally identified that the aftermarket intake piping had the dump valve venting internally but upstream towards AFM,close enough for it to read this additional airflow and send it confusing messages, hence some richness at idle and slightly uneven. They moved the dump valve closer to the turbo and venting to it, and the idle issue immediately resolved.

While the car was in bits I got the gearbox rebuilt and also did some suspension arms and bushes. It's all reassembled and running again and everything appears spot on. The clutch bite point is just so precise now, there are no untoward noises, the idle is stable irrespective of level of clutch engagement and there is no end float. I must say that the pandemic has helped me keep the car issue in perspective. Anyhow the mechanic won't be using engine builder 1 anymore. It must have cost a small fortune to rectify this and he didn't bat an eyelid over it. Very pleased such decency is still around.
I also learnt that I can be happy without an Evo in my life for months on end! That was surprising. But I'm happier now.

[LEGNUMVR4]

You'd be the first here I'd say to "upgrade" to evo 1-4 style thrusts

[zestyfesty]

Originally Posted by LEGNUMVR4

You'd be the first here I'd say to "upgrade" to evo 1-4 style thrusts

I guess time, and use, will tell.

[spn]

If you look at the WSM, the std value for end float is 0.05 to 0.25mm with a limit of 0.4mm.

The value you quoted is just over 0.1mm, which is well within spec.

Were the thrust bearings worn?

A 360 degree thrust bearing doesn't appear to be needed on the 4g63. On the E5+ engines (with the separate 180 degree thrust bearings) there have been virtually no cases of crank walk reported in the almost 25 years that they've existed).

Crankwalk occurs on the E1-4 engines with the integrated thrust and main bearings, which happpen to be 360 degree.

I think the issue is that they are integrated with the main bearing so as long as you have used separate thrust bearings, you should be fine but I suspect it was unnecessary.

[zestyfesty]

Originally Posted by spn

If you look at the WSM, the std value for end float is 0.05 to 0.25mm with a limit of 0.4mm.

The value you quoted is just over 0.1mm, which is well within spec.

Were the thrust bearings worn?

A 360 degree thrust bearing doesn't appear to be needed on the 4g63. On the E5+ engines (with the separate 180 degree thrust bearings) there have been virtually no cases of crank walk reported in the almost 25 years that they've existed).

Crankwalk occurs on the E1-4 engines with the integrated thrust and main bearings, which happpen to be 360 degree.

I think the issue is that they are integrated with the main bearing so as long as you have used separate thrust bearings, you should be fine but I suspect it was unnecessary.

Thanks.
A basic issue with clutch operation was cited as a possible cause. There was not quite enough free play at top, which may have been maintaining pressure on thrust bearing, but we don't know for sure. The clutch now works absolutely correctly, so confident if that was causal, it no longer is.
I thought that some of the early engine bearing issues were related more to the block design than the bearing design, the oil galleries supplying centre main bearing not aligning exactly with hole in cap? and oil supply not being adequate as a result, leading to premature wear. Please correct me if I'm wrong, I'm not a mechanic, but certainly curious. I was also told that some problems with the 360degree design was that the cradle could be ever so slightly misaligned and that could lead to uneven wear on thrust surface/
I'm happy the gents have been very thorough and I expect happy miles ahead. Cheers