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Vanishing MT Hydraulic Fluid


John124
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I have a 1991 Pathfinder SE that is constantly losing hydraulic fluid for the manual transmission. Obviously, it must be leaking some where, but I stumped as to where. The line from the master cylinder/reservoir, all the way up to the transmission seems fine -- no evidence of leaking. Someone once mentioned that it could be leaking behind the firewall. Is this possible?

 

Any help, comments, and suggestions would be greatly appreciated.

 

John

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Umm.. MZ, I do believe he is referring to the clutch fluid ;) ;) :lol:

 

 

Yes it is possible for the fluid to leak out the back of the master cylinder and into the passenger compartment. From there it would likely run down/drip down onto the floor board. However, one would think that eventually you would be able to smell it inside.... if not see it. Is the carpet wet or damp under the pedals? Even if it is not, look up in there and pull the carpet back and have a look.

 

Does your clutch work normally?

 

I trust you have completely inspected the slave cylinder mounted to the side (just for MZ :rolleyes: ... it's on the "bottom" offset to the right side) of the transmission.

Edited by RedPath88
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lol.. not one mention of the clutch red88.. where is the slave cylinder? lmao.. :D

I beg to differ -thnkboutit-

 

I have a 1991 Pathfinder SE that is constantly losing hydraulic fluid for the manual transmission.  Obviously, it must be leaking some where, but I stumped as to where.  The line from the master cylinder/reservoir, all the way up to the transmission seems fine -- no evidence of leaking.  Someone once mentioned that it could be leaking behind the firewall.  Is this possible?

 

To me, that all screams clutch :D

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Sorry for the ambiguity of my original post -- new to this site. Yes, I'm referring to hydraulic fluid for the clutch. Again, I apologize for not using the most appropriate lingo.

 

This condition has been going on for a while. It use to be that a full reservoir would last a month, and I just kept an eye on it. But nowadays, it'll run dry in less than a week if I don't stay on top of it.

 

When the reservoir has fluid, the tranny operates perfectly. But if I ever run it dry, the transmission will get increasingly difficult to shift to the point where you can't shift any longer, and there is no longer resistance in the clutch pedal. Then simply adding fluid back into the reservoir and pumping the clutch pedal several times, and everything is fine again.

 

So if fluid is indeed leaking behind the firewall, the master cylinder is faulty and replacing it will solve this problem?

 

Thanks again for the comments and insight. I'm a relative novice here.

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It does sound like either the master or slave cylinder. If the carpet is damp (slightly oily) behind the clutch pedal, replacing the master cylinder should fix it. If the carpet is dry, check the slave cylinder. Pull the dust boot back and check for fluid (can also do this on master cylinder).

If replacing the master cylinder, bench bleed the new part before installing it. Bleed the whole system after replacing either.

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John, there is no need to be sorry... I knew what you meant ;)

 

 

 

In addition to what Animal said, you need to get this fixed as soon as possible. By allowing it to run low enough to pull air into the system (it does not even need to by run "dry") it has negative effects on your clutch.

 

Not only does it make it harder to shift, but it will also promote wear on your clutch disk, resulting in the need to replace the clutch much sooner that it should need to be.

 

That wear is caused by the clutch not being fully disengaged when you depress the pedal, causing it to slip against the pressure plate at a point where it should not even be touching it.

 

This also creates a large amount of heat, which can cause the pressure plate to fail early as well.

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i had a slave cylinder boot bust on me...everytime i hti the cltuch it would work but it was leaking out that amount every time...good thing about that is i never had to bleed it...it bled itself so adding fluid got it fixed till i had time to change it...

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Once again, thanks for the comments... this is a a great site!

 

I just checked the area underneath the clutch pedal, and sure enough, I found where the clutch fluid was going to. I've been driving with this condition for quite a long time, and just recently found this site.

 

Thanks again.

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