08 gu iv clutch pedal / slow to take up hydraulic pressure-real hot day

Drove to Melbourne last Friday week, real hot day (high 30s), had traveled 300ks and had our first stop pretty well. Pulled over, engine still running, depressed clutch pedal and there was no resistance for say first 70mm (top travel) and was a bit clunky at that 70mm point where the pedal just took up hydraulic pressure. It also became a bit harder than normal to depress the pedal to the floor after several consecutive pumps of the pedal.

Fluid level was OK, may need changing, actually looked a bit discolored (dark) and clutch slave cyl and rod looked and seemed OK. Did check to see if the slave cyl was not getting too hot, eg: maybe the exhaust heat shield was not in place but all was OK.

Stayed put for a while (40min), kick had gone out of the heat of day as Sun was nearly setting. Drove off and all seemed to operate fine and has done so since (traveled 1200ks after problem).

Any thoughts?

First thing I would do is change the fluid? What exhaust do you have? If its larger the heat shield wont do a lot. I wrapped my dump pipe with exhaust lagging and found this helped a lot.

Sounds like air in the system, either from a leak or even boiling, but at 30 degC I doubt that. Sounds like what happened to the pedal on my brakes when I could not get the air out of the system. Bit tricky though if it 'came good'??

Thanks for input Mark & Phil.

Change the fluid - Will do.
Exhaust - 3" SS Berklee H/F (Cat/Muffler) turbo back.
Yeah agree, the heat shield at slave won't do a lot at all.
To wrap dump pipe with exhaust lagging - have never used this stuff, can U recommend brand/type? Any info to apply will be useful.

I think clutch defect was caused by higher ambient temp and higher EGTs on the day and think that both of you are on to it: the fluid may have got too hot on the day. As you will read, I had a boost issue which would have likely contributed to running at higher EGTs on the trip.

Was a hot day, we had to wet the dogs heads a bit to cool them down at Gundagai(mid arvo) and nearly touching 40 deg I recon. The clutch problem became apparent at Chiltern (sth of Albury). Clutch felt like there was air or lack of fluid in the system, but reservoir was full and no visual signs of leaks. I was also running 500-600 deg C EGTs most of the time (800kg 7x5' caged/tarp tow), decent hauls from Jugigong down thru over the divide, working @ 100-110kph.

Was an eventful trip, heading sth to Gundagai, lost low down boost and it would not come on until it was able to get spool up and saturate the cooler with air. Next thing no boost reading on VDO boost gauge at all, but yes the on board Ultragauge was displaying boost but it was poor/laggy behavior (measurement from MAP sensor via ECU / OBD11 port).

Hobbled into Gundagai, lifted bonnet and yes the boost gauge hard plastic line had broken completely away at the VDO blind ferrule fitting(located in cooler hot side tank). This probably contributed to higher that normal EGTs and along with the hot day could have contributed to the defective clutch behavior.

Off topic a bit here, asked myself, how long has this been gradually failing and possibly causing a progressive deterioration of performance especially low down. I did not hear any whistle sound at all and the adverse impact that the 2mm vent hole certainly surprised me. Just demonstrates how, the slightest boost leak can impact on performance and especially when running at higher boost levels (nom 26psi).

Anyway Friday (1645hrs), no spare ferrules with me, so found a mechanic/rural repair shop in Gundagai and the kind bloke fixed me up with a BSP hydraulic blanking end cap fitting to block off the venting air (no ferrules in stock) and then back on the road. The Ultragauge would only read max to 23.5 psi, as controlled by the ECU limited display output. But had boost back (presume 26psi) and improved EGTS
When I arrived in Melb (Sat), bought a pass thru std ferrule and all back to normal.

Worth noting (as you would probably know), the VDO ferrule fitting has a blind depth/annular groove that supports and crimps the hard plastic tube at one side only, and compresses the tube down against a solid spigot which can cause a circumferential cut into the tube wall section, if done up numerous times as mine has been and subsequently failed. IMO, prefer to use a pass thru dual crimp ferrule type of which is currently fitted and I consider this provides a greater degree of support and crimp action of the tube.

something like this mate.
https://www.ebay.com.au/itm/WRAP-50M...MwbK:rk:3:pf:0
If you use this, wear gloves and a long sleeve shirt. I wore gloves but had a T shirt on and my forearms were red raw, from lying under the car and wrapping it around the pipe my forearms were rubbing against the pipe.

Sounds like a fun activity. The one 10m x 50mm roll be enough?
Probably run from exhaust manifold to down to near rear eng mounts (back of G/box), must be so bad to apply up high near exhaust manifold.

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Originally Posted by Bidja

Sounds like a fun activity. The one 10m x 50mm roll be enough?
Probably run from exhaust manifold to down to near rear eng mounts (back of G/box), must be so bad to apply up high near exhaust manifold.

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I'm unsure how you would apply this to the manifold. It's a wrap. Unless you glue it on somehow. Pretty much from turbo downwards around dump pipe is the way to go ... Wrap it around and use the steel ties , done.

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Quote:

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Originally Posted by Hodge

I'm unsure how you would apply this to the manifold. It's a wrap. Unless you glue it on somehow. Pretty much from turbo downwards around dump pipe is the way to go ... Wrap it around and use the steel ties , done.

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Yeah mate my mistake, from turbo back it is. Had a look up there earlier to check out space, and will have to take heat shield off as she is all coated with exhaust soot residue. Exhaust to turbo gasket must be blown out or needs tightening up(cannot see where yet). Might even take dump pipe out to wrap. Will check it out.

Not a bad idea ...
While you've got it off... What's some kind of coating worth these days ... Ceramic ?

Quote:

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Originally Posted by Bidja

Yeah mate my mistake, from turbo back it is. Had a look up there earlier to check out space, and will have to take heat shield off as she is all coated with exhaust soot residue. Exhaust to turbo gasket must be blown out or needs tightening up(cannot see where yet). Might even take dump pipe out to wrap. Will check it out.

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Quote:

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Originally Posted by Hodge

Not a bad idea ...
While you've got it off... What's some kind of coating worth these days ... Ceramic ?



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Have seen this spoken about. The leak is very minimal at the moment as I do not hear that it is leaking at all. Will do a bit of searching about and see what the go is with the ceramic coating,