Clutch master cylinder warning!

[beretta]

Hi all,

Just thought it would be worth posting up my dramas with my clutch in the last few days. I had a crook master cylinder which was replaced by my mechanic, he ordered the master cylinder from a clutch and brake mob, and specifically asked for one for a diesel. Anyway as soon as I started driving in traffic I started loosing (slipping badly) clutch as it was slowly building up pressure and keeping the clutch open. But as soon as I cracked the bleeder under the bonnet it pissed fluid out and then would be fine Anyway it turns out that they supplied a Petrol Patrol master cylinder and they're different to a diesel.....the bore on the petrols is longer and therefore builds up pressure as I slowly use the clutch. So if you are ever replacing your clutch master cylinder, make sure you definately get a diesel one! At one stage I had to stop using the clutch as much as possible driving through Melbourne, pain in the ass!

Hope it helps someone.

Cheers,

Paul

[paazau]

Hey Paul,

chops put me onto your post as I've been trying to get to the bottom of my clutch problems. The free-play and resistance on mine changes as I'm driving, as does the height of the engagement of the gears. If I get my toe under the clutch pedal and pull it up the free play returns and engagement goes back to normal. I've recently had slave, master and now clutch plate replaced. I have a GY Patrol, 4.2 Diesel. Not being mechanically minded, I can't determine if what you are describing is similar to my problem. Does it sound like it to you? Guess it's worth asking the mechanic to double-check that I got a diesel master cylinder regardless.

[beretta]

Easiest way to tell if you have the right master cylinder is....the Petrol ones have a goose neck in the reservoir (where the fluid goes), whereas the Diesel ones have a normal straight up cyclindrical reservoir, do you get what I mean? If it has a goose neck like I said then its a petrol one and the bore where your clutch booster engages the cyclinder is a good 5 - 10mm longer which means it builds up pressure in the slave cylinder as you use the clutch.

Now a question which might also help......if you pump you clutch a few times, then go and crack the bleeder up the top under the bonnet, does it piss out like its under pressure? If it does then this might be the problem.

PM me if you want to talk and I can give you my phone number.

Hope that helps!

[matthewK]

i'll actually try that tomorrow i'll let u know

[krimnl]

Easiest way to tell if you have the right master cylinder is....the Petrol ones have a goose neck in the reservoir (where the fluid goes), whereas the Diesel ones have a normal straight up cyclindrical reservoir, do you get what I mean? If it has a goose neck like I said then its a petrol one and the bore where your clutch booster engages the cyclinder is a good 5 - 10mm longer which means it builds up pressure in the slave cylinder as you use the clutch.

Now a question which might also help......if you pump you clutch a few times, then go and crack the bleeder up the top under the bonnet, does it piss out like its under pressure? If it does then this might be the problem.

PM me if you want to talk and I can give you my phone number.

Hope that helps!

i think you will find there difference is betwenn a boosted and non-boosted clutch. i know my petrol shorty without a booster runs the straight master , but one with a clutch booster runs one with the dogleg you describe.

[matthewK]

mine the 88 GQ 4.2 petrol run the boster with the goose neck looking res

[beretta]

Easiest way to tell if you have the right master cylinder is....the Petrol ones have a goose neck in the reservoir (where the fluid goes), whereas the Diesel ones have a normal straight up cyclindrical reservoir, do you get what I mean? If it has a goose neck like I said then its a petrol one and the bore where your clutch booster engages the cyclinder is a good 5 - 10mm longer which means it builds up pressure in the slave cylinder as you use the clutch.

Now a question which might also help......if you pump you clutch a few times, then go and crack the bleeder up the top under the bonnet, does it piss out like its under pressure? If it does then this might be the problem.

PM me if you want to talk and I can give you my phone number.

Hope that helps!

i think you will find there difference is betwenn a boosted and non-boosted clutch. i know my petrol shorty without a booster runs the straight master , but one with a clutch booster runs one with the dogleg you describe.

Ah yes, forgot to metnion that, there is definately a difference like you said! Thanks Krimnl

[paazau]

If we're talking just the reservoir, it's definitely a straight cylinder. I remember that much from looking at it. Mine doesn't have a booster, so it sounds like that should be what it's running. I've asked the mechanics to check back with the parts supplier anyways to make sure I have the right one for a diesel, non-booster clutch. I've tried to attach a picture of my master cylinder that I took with my phone. <not sure if it'll work or not>>

Haven't tried pumping the clutch and cracking the bleeder, but will give that a go and let you know.

I find it amazing that I haven't had any clutch problems for the 4 years I've had this Patrol and since taking it in to have the leaky slave fixed I've had all these problems. And from reading the bb it sounds like I was lucky to not have problems for those 4 years!

[matthewK]

Now a question which might also help......if you pump you clutch a few times, then go and crack the bleeder up the top under the bonnet, does it piss out like its under pressure? If it does then this might be the problem.


i did this yesterday and it just dribbled out no pressure

i think its my servo on mine had to pump it one or twice when first started and one during a trip

matty

[matthewK]

been a few days now and it gone back to pumping all ther time again so it servo or clucth itself