To much vacuum maybe

[Booney]

I have a GU 4.2td and Having a drama with my clutch peddle staying on the floor. Replaced booster and slave with no change . Could there be to much assist vacuum

[Woof]

Very poor effort for your 1st post mate......no Hi, Please or Thanks.
Don't expect too much assistance, my advice is to try again with an Introduction

[AB]

As above mate, throw up an intro about yourself.

I don't think you can have too much vacuum but I could be wrong. I'm running both alternator Vac and TD42T vac from other side of block and its working a treat.

Throw up an intro about yourself in the intro section and hopefully others can help out.

[nissannewby]

Master cylinder normally has this behavior when it has failed.

Cant have to much vacuum.

[Booney]

Yeah hi sorry fella's. First time poster an new to this sort of thing. I live in central qld and have been working far to much to enjoy life . Frankly would rather be fishing but with the patrol playing up haven't trusted it at the ramp
So the problem i have is with the peddle sticking on the floor . I have bled the system quite a few times then replaced the slave piston and reservoir and checked the line for leaks . I have just replaced the master cylinder and still getting the same results. The last thing i tried was a cheap vacuum guage on the assist line and it was reading -30psi
Any assistance would be greatly appreciated and thanks in advance

[MB]

Welcome aboard Booney mate. PeeBee Phil mate. What was the similar as Booney’s issue fix you found when doing your twin pot caliper modifications/swap mate?


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[PeeBee]

My issue was looking like a failure in the master cylinder, pedal was sticking to the floor and then was getting notchy, however the real problem was I had installed the new twin pot calipers on the wrong sides, ie they were actually upside down with the bleed nipples on the bottom instead of the top, so there was no way I could bleed them. Once I engaged my brain, and spoke with a real motor mechanic, he was right onto it! I did replace the master cylinder initially, but made no difference, so I think the issue is different to mine.

What I would say though is make sure you follow the manual and get the air out of the master cylinder, and also make sure you bleed the valve on the top of the diff as well. I think the action is bleed thru to the diff top valve, then RL, RR, FL and finally FR caliper, watch the reservoir level also.

[MB]

Cheers Philstar, is that the rear proportioning valve thingy you mean mate?


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[PeeBee]

Yep, could not remember its name, thanks

[MB]

All good mate, forgot what I had for breakfast, do we have a problem, and by “we” I mean “me” :-)


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[PeeBee]

Nup, if its not important the old memory bank does not need to hang onto it I reckon. So, like a gold fish, tomorrows breakfast will be a total discovery joy!

[GeeYou8]

The last thing i tried was a cheap vacuum guage on the assist line and it was reading -30psi
Any assistance would be greatly appreciated and thanks in advance
You can't get -30 psi of suction, atmospheric pressure is only around 15psi absolute, -30 in,Hg maybe. You physically can not get too much vacuum.