Christmas Eve I was out still getting last minuet gifts when I came to a stop and the truck wanted to keep on going,

So on Christmas Day I replaced one of the diaphragms to the vacuum pump (I bought this last week just in case) but the brakes were still flaky so I checked the vacuum and found I am getting between 5"-10" with a very unsteady pointer, I checked all of the vacuum lines and when I unplugged the check valve from the booster and held my finger over the open port, the vacuum shot up to 20" and held it steady.

So Sunday I called NAPA and bought the complete booster and master cylinder.

I installed the remanufactured Master Cylinder and Brake Booster from NAPA yesterday, wasn't too bad other than lying on my back under my dash reaching through about 500 miles of tightly bundled wired to reach the 4 nuts and then with the assistance of my wife I bled all of the wheel cylinders, got everything cleaned up and went out for dinner, I stopped for fuel and decided to pop the hood and check the brakes and I found that the new master cylinder is leaking brake fluid from under the cover and onto the frame rail.

I cleaned it up and popped the cover not knowing what to expect and found the fluid level where I had left them about 1/2" below the top on both sides.

I drove home about 5 miles and came out and checked it again and found the bottom of the master cylinder dripping with fluid again???

Looking at the cover I removed the rubber gasket and the inside of the metal cap was also wet with fluid, the wire bail that secures the cover is tight and you cannot move the cover once it is fastened down but still the brake fluid is escaping.
I did notice that the top edge of the master cylinder where the gasket sits if all nicked and beat looking and is probably where it is leaking from.

This master cylinder looks like it has been dropped or tossed in a big pile of other cores where the sealing surfaced have gotten all banged up and someone grabbed it and replaced a few parts and called it good.

I didn't think I would have had to check the surface before I had installed it.

Today I am going back to NAPA and tell them to give me another one and I will be sure to inspect this one be for I leave the store.

This one was remanufactured by A1-Cardone, they also supply Pep Boys, Kragen, Auto Zone and a host of others.

One would think NAPA had a bit better quality part than Kragen or Pep Boys but I guess not.

http://www.napaonline.com/Search/Det...+50022+2022022

So what do you think, is this where my leak is comming from?

Jim

 

I've had 3 master cylinders from Napa (one on warranty) on my Dodges now. They all seemed to weep around the top!!! Like you said, level is still 1/2" or so below the top, wire bale is tight, etc.

I noticed on one of them that there were little flakes of metal embedded in the rubber gasket!

On the last 2, I rubbed some grease onto the rubber of the gasket. I sprayed the whole Master/Booster assembly with brake kleen to wash off the phosphorous coating and gave them all several coats of engine paint. During this time, I think the grease softened the rubber to make it seal better. I now don't have the paint peeling on my master cylinder. Maybe give it a shot?

BTW: The one I returned was leaking from the aft seal between the master/booster from day 1!! It was a loaded (combined) unit to boot.

 

Chalk up another leaky booster from Napa with Banned Member Loco1's 1992 D/W250. He even painted it up nice before the install only to have the brake fluid run down and eat it all up.

I have been VERY dissapointed with Napa lately. I went in to get D60F Carrier Bearing races because they were the only ones that had them in stock (I got TIMKEN Carrier bearing cones from Auto Zone but the race 382S was special order) and they brought the SKF to the counter and it had the dreaded made in CHINA / Hecho En CHIN on the back. I politely refuse to put those races in my truck.

 

I got a master cylinder for my buddies d350 from autozone and it leaked because the gasket for the lid shrunk up.

 

While working as a technician, I had seen so many rebuilt master cylinders with a rough sealing surface, that I had decided never to install a rebuilt master cylinder again. The same goes for rough gasket surfaces on rebuilt water pumps. Luckily there are now several manufacturers making NEW master cylinders these days, and the quality doesn't seem too bad.

 

I don't see how it would mess anything up if you knocked a couple thousanths off the top of the mastery cylinder and get a nice fresh surface?

Maybe check with a local machine shop that has a mill?

 

This isn't really aimed at Jim Lane because I know he is going to fix the problem, but many of us (guilty!) are not as particular about our trucks as him. It's tempting to just let it seep, the truck stops OK after all, what's the big deal? If fluid can get out, air can get in. With air comes moisture. Water in the brake fluid lowers the boiling point, making your brakes fade sooner. Even worse, it makes the brake system rust inside, leading to leaky wheel cylinders and ruptured hard lines. Fix it, even if you have to buy a new master.

 

I put a light bead of GMS (General Motors Silicone) to the surface of the master after sanding it a little with some sand paper. Mine has no leaks now and it's full to the top. I'm guessing the new one you get will be of the same "quality" as the old one.

 

if new masters and boosters are available for our trucks where can I get 'em? and don't say the dealership...

 

W.W.J.D.?

That is what I was going to do when I got my replacement master cylinder, I used to do this when I worked on V-730 and Allison Transmissions, I would lap the surface of the valve bodies on a large piece of glass and a piece of 800 or 1200 wet/dry paper or crocus cloth face up.

The only concern I would have doing it to my master cylinder is if the raw surface would rust but it would all be covered with the gasket so it should be all right.

You could do this on the truck if you had to after you emptied out the fluid and stuffed the reservoir with a rag just below the top then either with a piece of 1/4" safety glass (wear heavy gloves) or a sturdy block of steel of aluminum wrap some #180 wet/dry paper around the block and carefully polish it using an X pattern from front to rear, side to side.

After it takes the rough cut the paper will flatten out and become finer and you should end up with a nice flat surface.

I would then swab it out with a strong magnet to pick up all of the filings and then very carefully puff it using compressed air and then remove the rags.

Fill using fresh dehydrated brake fluid and bleed them till you get a few ounces out of each cylinder.

This should stop any leak that might come from under the lid.

This is just what I would do.


Jim

 

Thanks Faith.
On Monday I went to NAPA to return my old core and told him I needed him to get me another one because the new one was leaking out of the top, (the new master cylinder/ booster unit I just got did not even come with a hose set for bleeding , I had to make my own) he acted like it was a surprise so I had to explain to him why it was happening, we have another major parts rebuilder here locally and they turn out some pretty bad products, I had walked through the shop and it looked like they went to Home Depot and picked up a bunch of day laborers and called them technicians, I have gotten water pumps without impellers, sealing surfaces on water pumps so pitted that it would not seal, alternators without brush springs, dirty commutators.

He said the replacement will be here tomorrow, I ask him if they had new master cylinders and he said they have them in stock at about $72.00 or $44.00 for the remanufactured ones.

Remanufactured Master Cylinder @$43.99

http://www.napaonline.com/Search/Det...+50022+2022022

New Master Cylinder @$71.99

http://www.napaonline.com/Search/Det...+50022+2022022

Remanufactured Power Brake Booster only @$102.49

http://www.napaonline.com/Search/Detail.aspx?A=NBB5473360_0136012400&An=599001+1019 91+50022+2022022

Remanufactured Power Brake Booster with Master Cylinder @ $143.49

http://www.napaonline.com/Search/Det...+50022+2022022

All have a lifetime warranty.



I am going to talk to the manager and see if I can turn this into a New master Cylinder, Remanufactured Booster combo for the cheaper price.

I really do not want brake fluid dripping anywhere onto my truck, this stuff removes all of the paint and causes the metal to rust.


Quote:

Water in the brake fluid lowers the boiling point, making your brakes fade sooner.

Remember way back in the olden days when the brake line used to pas by the exhaust manifold and you would end up with your brake system getting a vapor lock and not working at all, happened especially in high altitude while descending a winding mountain road.

I remember our 1953 Buick Roadmaster along side the road and pouring cold water over the master cylinder and brake lines to try and condense the vapor so we could go a few more miles, this was also very common to vapor lock your fuel pump.


Jim

 

Yea I've had that problem where I get a broken part install it and it gets me pretty frustrated. Learned to check always before I leave.

 

Ok I went to NAPA this afternoon the see what they were going to do with my leaking master cylinder, when I walked in the guy behind the counter said I got your parts in for you.

I told him that I really do not want to take a another chance wasting my time installing another remanufactured unit and have the same thing happen or worse so here is what I want you to do..

Ill keep the booster because it seems to be working ok for now and then I want to buy a brand new master cylinder for the same price or give me your best discount, I will replace the leaking one and then I will bring you back the leaking one so you can defect it and then pay me my money back.

He thought about it for a few minuets and then said OK..

So after all of talking and whining, I wound up with a Remanufactured Brake Booster and a NEW Master Cylinder all for the original price and all with a lifetime warranty.

Now as soon as it stops raining AGAIN I will install my new master cylinder and I will be happy.


Here is the number for the new one:



Check it out..



I am going to check this on a piece of glass before I install it just to make sure.

I don't think I will have any leaks with this one.




Jim

 

Mine always leaked on my 90. Hopefully the new ones are the way to go. Keep us posted jim.

 

I went through this nightmare on my truck... ordered a new bendix one from napa and it hasnt leaked since...