Landcruiser clutch nightmare

[Tim203]

Apologies for this not being a Benz problem but I know there are a lot of clever people on here. A work colleague has a 100 series 4.2 diesel manual that developed a strange clutch slip at constant Ioad motorway speeds. The clutch would just let go without warning . The previous owner had said the clutch was getting tired so we replaced it. Upon inspection it didn't appear unduly worn. Guess what, new clutch, same problem. My friend bypassed the inline accumulator and has just replaced the master cylinder all to no avail. If you dip the clutch after it starts slipping it's ok for a bit. It's almost as if there is a servo somewhere building up pressure but the system is as basic as it gets. Originally I thought it could be a viscous coupling but there isn't one. Any ideas gratefully received as the local main dealer has no idea either!

 

[Giantvanman]

did he just replace the cloth plates or did he use a kit? Paragraph three on here Toyota Land Cruiser Clutch, Toyota Land Cruiser Clutch Kit - FREE Shipping might be a clue.

 

[Tim203]

We fitted a new pressure plate and thrust bearing, wiped flywheel etc, thanks a lot for the link.

 

[Giantvanman]

It's almost as if there is a servo somewhere building up pressure but the system is as basic as it gets.

Just trying to think about this so excuse the havering…..
It has a clutch slave cylinder on the system; is there any way it could be being pressured gradually by the linkages between it and the pedal? Is there maybe a weak return spring?

 

[grober]

Has the car got a dual mass flywheel? They don't "slip " as such and can only rotate 20-25 degrees. However if a weakened flywheel was occassionaly to " let go" would this sudden shock rotational loading on the clutch be enough to start it slipping if under power at the time? This would fit with the description that dipping the clutch restores drive till the next flywheel "incident" . Normally clutches are not asked to disengage/engage with an engine transmitting much power. Some folks advise changing DMFs with the clutch.

 

[Tim203]

Thanks for your reply. Not a dual mass and didn't show signs of excessive wear IMO. Strange thing is the symptoms are exactly the same as before. No better, no worse, only seems to happen at constant load say on the motorway or fast A road.

 

[brucemillar]

Long Shot Alert:

I had an M3 Evo that would slip the clutch when hot (stationary traffic). That turned out to be a hydraulic clutch fluid pipe that was expanding under heat. A quick visit to Pirtek sorted out a nice braided high temp hose.

 

[John Jones Jr]

A couple of wild shots. Double check that you were supplied with the correct clutch. There's a 105 non turbo and the 100 turbo. Also check that transfer box is correctly engaged for either 1st or 2nd.

 

[jonnyboy]

Land Cruiser Club - great bunch of lads over there, very knowledgeable.

 

[cazyp]

Were the slave and the master replaced..?

 

[John Jones Jr]

''Were the slave and the master replaced..?''

I can't see it being faulty master or slave cylinder as the clutch is always engaged? If either was leaking/sucking air the clutch would still be engaged. The only other explanation I can think of is that there's some binding going on and the clutch is not fully engaged at anytime.

Since it's occurring while the car is at speed that would suggest the engine is probably producing near enough maximum torque and suffering from high wind resistance thus highlighting lack of full engagement. At a bad guess I'd be looking again at the slave cylinder and clutch fork operation/alignment.

 

[Tim203]

Were the slave and the master replaced..?

Master replaced , slave next + hose, thanks.
Also fork cleaned and lubricated and new thrust bearing. Bizarre thing is all the theories of hydraulic problems seem counter intuitive as when it slips and you dip the clutch a couple of times it's ok for a bit.

 

[Stratman]

It's not something like the fork pivot preventing the clutch from fully engaging or something like that, is it?

 

[Tim203]

It's not something like the fork pivot preventing the clutch from fully engaging or something like that, is it?

When we put the g/box back in( bloody heavy like a truck!) there was free play on the fork before the slave cylinder was reassembled. Thanks

 

[Tim203]

A couple of wild shots. Double check that you were supplied with the correct clutch. There's a 105 non turbo and the 100 turbo. Also check that transfer box is correctly engaged for either 1st or 2nd.

Clutch kit ordered from Milners and AFAIK a quality kit . I will ask about the 105 possibility though. Thanks.

 

[Egbert Nobacon]

Give Julian a ring at Overland Cruisers.

What he doesn't know about Landcruisers isn't worth knowing and he's very helpful on the phone if people are having issues they can't resolve.

http://www.overland-cruisers.co.uk

 

[grober]

Are you absolutely sure the car doesn't have a DMF? Most modern diesels do?

 

[jonnyboy]

A 100 diesel is not exactly modern technology Graham - it wont be a dmf.

 

[cazyp]

Were the slave and the master replaced..?

''Were the slave and the master replaced..?''

I can't see it being faulty master or slave cylinder as the clutch is always engaged? If either was leaking/sucking air the clutch would still be engaged. The only other explanation I can think of is that there's some binding going on and the clutch is not fully engaged at anytime.

Since it's occurring while the car is at speed that would suggest the engine is probably producing near enough maximum torque and suffering from high wind resistance thus highlighting lack of full engagement. At a bad guess I'd be looking again at the slave cylinder and clutch fork operation/alignment.

Master replaced , slave next + hose, thanks.
Also fork cleaned and lubricated and new thrust bearing. Bizarre thing is all the theories of hydraulic problems seem counter intuitive as when it slips and you dip the clutch a couple of times it's ok for a bit.

Having had a couple of these my money is on the slave or an expanding hose.

 

[Tim203]

I reckon the thrust washers have dropped out of one side of a journal, the helical gear driving the oil pump is pushing the crank backwards and when the clutch is dipped it pushes it forwards again. Saw something similar on a Fiat spyder ( driven around Munich all it's life and never been put into neutral at the lights). The block was completely rodgered where the crank had eaten into it . It would also explain low biting point on pedal.