I have had some terrible luck with master cylinder and my truck. Got a reman master cylinder last february, that one leaked out the top. Got another reman, that one also leaked out the top. Got a new master cylinder, this one leaked out the rear seal. Finailly i got another new master cylinder, bled it today and a couple hours later i noticed it was leaking out the rear also.

The linkage is not adjusted out too far, I bench bled the master cylinder according to the directions in the box, but found that i had to bleed it a bit more on the truck to get all the air out of the front brake resivoir (rear resivor on cylinder). Is this just a fluke that two new master cylinder rear seals have gone bad or could i bee doing something wrong?

All of the cylinders both new and reman were cardone from advance auto parts. Where should i order my next new one? Certainly not buying another one from them.

 

Rossta, I for one have had my share of problems with Advance- ESPECIALLY Remanufactured pieces . Generally, If I absolutely have to go with rebuilt parts I go to a company here in Richmond Virginia where I have known the owner for many years and I know the employees as well. Secondly , I used to work or N A P A in 1968.I also still swear by their parts too . Iseldom have to haul a rebuilt part from them back , but it has been known to happen. Look buying fromKragen, Chief, Pep- Boys , and Western Auto is usually a waste of your time . Go with Big A or N A P A , even Federated will stand behind their product better than the " discount " parts chains . Ed Shaver

 

I was thinking about going with a N A P A master cylinder this next time and you have just confirmed my decision. Thanks for the reply.

 

I do all of my business with NAPA, and an very happy with everything I get from them with the exception of a reman starter last fall, that was locked up. However, after getting their minds right they replaced it, and all is good.

Actually I was just there a bit ago, and picked up some stuff, and was looking into the next arm full of parts I will need.

As to your problem, I would NEVER deal with a reman master cylinder. I priced them at NAPA , and if I remember correctly, it was only $5 more, which is a no brainer, but still not a guarantee!!

So good luck, and if they are near you, give them a shot. I like NAPA, and it seems to me, the other ones seem to cater to the rice burner, fart tubed, bumper draggin, backward hat, pants down to their ankels group who wouldn't know the sound of a good motor if it ran them over!!

 

Napa and Carquest are good choices. Try to use new rather than rebuilt on master cyll's. When i get a power booster and it comes witha rebuilt master on it already I take it off and replace it with a new one instead of risking a comeback on a poorly rebuilt unit. I always figure you can't be to safe when it comes brakes and your life!

 

Can't your local Ford dealer get one ? I always go there for master cylinders and have never had a problem with one.

 

I also had two master cylinders in a row, leak out the top. I purchased one from NAPA and haven't had any problems. NAPA seems to carry decent parts and stands behind their warranty. They have cross referenced some Ford part numbers for me for some hard to find parts. I had a friend who worked for NAPA and he would get parts for his cost, at least 50% off. Now he works for O'Reilly. Just not the same quality.

 

For those of you that have leaks form the tops of your master cylinders. Use the old cover that was originally on your truck. Something about aftermarket gaskets for the tops and thin stamped steel covers just dont seem to provide the right tension to keep them from leaking. Notice that with the new covers and gaskets you can open the spring with your hands and the original one has to be pryed with a tool?
Tension is the key and original lids and gaskets are almost essential.

As for leaks on the pushrod or shaft. Make sure that the shaft is clean and free of any corrosion. If the shaft has rust (I can almost gurantee that 99% of them do) the pits and imperfections can cause the vacuum booster to draw fluid out of the master. It is not the fault of the master cylinder. This is why fellers have so many problems with master after master. Same problems means that there is a common problem.

Rusty components will not create a smooth enough surface for the seal to work against and the result is a leak.
In one case, I used a piece of heat shrink tubing over the push rod. Yup, electrical heat shrink tubing. The tubing will create a new surface so the seal can keep the vacuum away from the inner seals and will not pull fluid through them to the booster.
This was a field fix that I performed about two years ago. I have all new components but wanted to see how long the fix would last. Still counting.

Check all of the components to make sure that they are clean and serviceable.

 

75f350,

I thought about the brake booster vacuum pulling fluid out of the master. I concluded in my own mind that, the 18-20 in of Hg ( i think thats right) at idle shouldn't be enough to cause problems with the oring sealing in the master cylinder bore. Looks like my assumptions could definitly be wrong.

I blocked off the hose to booster and the engine speed didn't change at all, so i also concluded that the booster couldn't be leaking any?

I know that the rubber seal and pushrod on the booster probably are not in the best of shape. I will see if i can clean them up some today. Are you pretty much forced to buy a reman brake booster if these parts wear out?

 

Not necessarilly, I have purchased new pushrods seals, and have found them in the salvage yards. Huge difference between my climate and others is that in my area things do not rust all that bad. While I have found some rusty stuff, the problem just is not as bad as other in the snow belt may have it. The seal has a part number on it and a good parts house can reference this number for a replacement.
The small seals on the plunger inside of the master are cup shaped, almost like an umbrella, and really only seal very well in once direction. It will not take much vacuum to draw fluid out through these. You may find that the level drops over a period of time.
When my last booster pulled vacuum through the master, I did not notice a vacuum leak. SInce it was only pulling through a small leak around the small diameter push rod, it was only drawing fluid. Matter of fact, the engine idle and performance did not change. Though it did draw fluid into the booster the amount was so small that it was hardly noticeable. I did run the master out of fluid once though, and that was when I new I had a problem, and knew it had to be in this area. It was my dad that noticed a smell from my exhaust. He was behind me on a trail. After workng the brakes to extremes, he told me that he smelled that smell again, and I called him crazy. Was not more than a few minuted later that I pulled all of the fluid out of the reservior. I dont call him crazy any more. That was an experience! After I limped the truck a few hundred miles home. I say limped because even though I seldom had to touch the brakes, as long as the truck was running it was drawing fluid into the booster. I did disconnect the booster, and while this helped, my problem was such that I soon started pushing fluid out of the master itself.

Anyway, this may not be your problem, but it is sure worth looking into.

 

Thanks for the reply and explanation. I pulled the pushrod and seal out today. There was a little bit of rust/corrosion on the rod and seal. I cleaned both, as well as the housing with a little sand paper. Lubed everything and reassembled. Im going to pump the brakes up without starting the vehicle to see if the master cylinder leaks. If it doesn't i will try it with the engine running. This should tell me if the booster is the culprit. Thanks again for the replys everyone.

 

After 5 pumps on the pedal with the engine off and several minutes there was a nice stream of fluid running out of the master down the booster. Im going to try a new master cyl from napa. Ill let you guys know what happens.

 

After 5 bad master cylinders from Advance Auto, the first one i bought from NAPA does not leak and works great. Now i just need to see if i can get any money back from advance auto.

 

Glad to hear you go it fixed!!