purecountry49

I am new so bare with me. Need experienced suggestions!!!!!!

I have a '92 Dodge 3/4 ton, Diesel 4 x 4 Ext. Cab,

I have not driven this truck much for 3 yrs. Just recently I have decided to enlist this truck again as a trailer pulling vehicle. I noticed that I had brake fluid coming out from under the master cylinder cover. I changed the master cylinder and still have the same problem. I did bleed the master cylinder as directed in my service manual and have bled each wheel cylinder as directed. Still have the same problem but not as bad. I had changed the master cylinder a few yrs. ago because of low and mushy brake pedal and replaced rear and front pads and linings. I do remember having this problem after I changed the master cyl. and that is why I changed it again.(It was under warranty).

Can anyone shed any light on this for me??

Thanks Up Front

Will

John Faughn

Its hard to tell by your description , as an example , under the master cylinder cover , my guess is the reservoir cover .
Then again is it coming from the cover seal area ?
Or at the point where reservoir connects to the mater cylinder ?
It sound unusual , if they are from the same rebuilder / manufacture , then they may be making the same mistake .
Can you take pictures ?
Have the supplier look at it , make a refund if not resolved , by from somewhere else .

purecountry49

Brake fluid is definitely coming out from under the cover, I bought a new cover and gasket and it is still coming out from under it!!

John Faughn

There's no way to tell your abilities at this time , a good mechanic , always goes back to the basics while continued testing .
I say that to help avoid you thinking that I may be saying something about your abilities [ unknown ] .
What is the level in the res. ?
It should be visible that the sealing surface is good or bad .
What volume , is leaking out ?

purecountry49

Hey John, Thanks for the help!!!! There was a time when I worked as a mechanic on heavy trucks, Cummins, Detroit, Cat engines and some Thermo King work. Have done brake work but that was not my specialty. Sorry to say but my working as a mechanic every day was almost 30 yrs. ago. Fluid level, 1/2 in. from top of res, sealing surface is good. I have checked in my service manual in regards to some sort of pressure build up or back flow through the combination valve. I just came back from a drive in that truck and it is leaking out the cover still but not a lot of volume.

NO_SPRK

these masters never seal right. i have had plenty and everyone leaks on top. i suggest bleeding the system good, filling it up, clean both surfaces and using a little bit of silicone.

John Faughn

I've been out of the buis. for about 5 yrs , manly because $60,000 in tools were stolen , after about 25 yrs.
I will have to get a look under the hood of a 1st , gen , but have never seen any car / truck leak , like you & NO_SPARK mention .

purecountry49

WEll after a little more research, I have come to knowledge that the '94 went to a removeable plaster res., the bore is 1 1/4 instead of 1 1/8 as in '92. Seems to be physically an interchange or maybe even an upgrade. I wonder if it will fit. Any thoughts

Thanks Up Front

Jim5870

I have often wondered if there was a better unit that will bolt on,
my cylinder covers allways weeped on my trucks.

purecountry49

I am going to a salvage yard today and see if I can purchase the later style master cyl. and just see if it will physically fit. I will report the outcome.

brainfade

I'm pretty sure the bolt spacing is different between the two. Since the plastic res. model is for a hydroboost system the pushrod length on the booster is also going to be different.

What you might want to think about is grabbing the whole hydroboost and puting it in your truck. It takes a little fab work but is reported to be well worth the effort. There several threads about this swap if you do a search.