I need help. No brakes

[Mmorgan32]

So driving home today all of the sudden no brakes what so ever. It started off slow, every other time I pushed them the went down alittle further than usual then Back to normal. Then all of the sudden nothing. I have power drum brakes btw. So got it home and my master cylinder cap was extremely hot but it is 105* outside today. It has plenty of fluid. My question is can the brake fluid get to hot to where it don't work or do I just need to bleed my brakes? I have every once in awhile gotten some brake fade too.

[cdowns]

sounds like a baD MASTER CYLINDER

[Mmorgan32]

How can I be sure? And what is bench bleeding?

[Mmorgan32]

Does that fact that my master cylinder was really hot throw any red flags? It's my daily driver and I don't have time to do a new master cylinder unless I have to. Any other opinions or does everyone think the master cylinder needs to replaced? Your help is greatly appreciated

[Mmorgan32]

Another question all I can find is a disc brake master cylinder will that work with my drum brakes? I do plan on doing discs one day anyways

[JPBrecheisen]

Originally Posted by Mmorgan32

So driving home today all of the sudden no brakes what so ever. It started off slow, every other time I pushed them the went down alittle further than usual then Back to normal. Then all of the sudden nothing. I have power drum brakes btw. So got it home and my master cylinder cap was extremely hot but it is 105* outside today. It has plenty of fluid. My question is can the brake fluid get to hot to where it don't work or do I just need to bleed my brakes? I have every once in awhile gotten some brake fade too.

Brake fluid can get hot to the point where you pedal can feel spongy or not as firm. Did you check it again after it had time to cool off?

If you don't see any fluid leaking from between the drums and backing plates indicating an excessive fluid loss from a bad wheel cylinder, I'd vote on the master cylinder also.

[JPBrecheisen]

Originally Posted by Mmorgan32

Does that fact that my master cylinder was really hot throw any red flags? It's my daily driver and I don't have time to do a new master cylinder unless I have to. Any other opinions or does everyone think the master cylinder needs to replaced? Your help is greatly appreciated

If its 105 outside, then just about anything under the hood of that truck is going to be too hot to touch when you first pop the hood after its been driving in traffic or down the road a bit.

If the master cylinder cap is the hotter than everything else, then that could be something. Otherwise, its probably just hot because its sharing a room with a old V8 engine on a day when its 105.

I doubt you have a fluid heating problem. Normally you need to get brakes really overworked and hot (like a racing type situation) to feel any major degradation.

Look for fluid loss on the wheel cylinders hoses etc....if its all dry, its probably the master.

[Mmorgan32]

Originally Posted by JPBrecheisen

Brake fluid can get hot to the point where you pedal can feel spongy or not as firm. Did you check it again after it had time to cool off?

If you don't see any fluid leaking from between the drums and backing plates indicating an excessive fluid loss from a bad wheel cylinder, I'd vote on the master cylinder also.

Yep fluid still full. No fluid loss at all. I did replace my gasket the other day but didn't bleed them. Figured I'd just do it this weekend. I really don't think having the cap off for 5 minutes would cause this.

I had no ped what so ever. I had to drop it in neutral and press as hard as I could to stop.

Ok so I need a master cylinder will a disc brake one work for drum brakes? I don't have a proportioning valve just a block and what I am assuming is the switch due to the wire coming out of it

Thanks everyone I really appreciate the help

[leftybass209]

Do you know the age and condition of your master cylinder? None of those parts are overly expensive, so it's really an easy call to replace with new stuff. Drum brakes can use all the help they can get!

[JPBrecheisen]

Originally Posted by Mmorgan32

Yep fluid still full. No fluid loss at all. I did replace my gasket the other day but didn't bleed them. Figured I'd just do it this weekend. I really don't think having the cap off for 5 minutes would cause this.

I had no ped what so ever. I had to drop it in neutral and press as hard as I could to stop.

Ok so I need a master cylinder will a disc brake one work for drum brakes? I don't have a proportioning valve just a block and what I am assuming is the switch due to the wire coming out of it

Thanks everyone I really appreciate the help

Bleeding wouldn't be required if you just had the cap off. Bleeding is only required if the master was replaced or the system was opened up at any point down stream of the master.

I don't understand why you can't find a master for drum brakes. You should be able to get one from a local parts store by searching year, make, model.

You can probably get a decent remanufactured one for $30.

[Mmorgan32]

It's old as hell. I'm sure it's all original. I called Napa and summit all they have is for disc. I'll call around. Thanks

[Keith Seymore]

Originally Posted by Mmorgan32

Ok so I need a master cylinder will a disc brake one work for drum brakes?

No.

Rock Auto will have the right one, too. I've ordered three within the last couple weeks for different projects (drum/drum), and you could pay a couple extra bucks and have it overnight.

K

[Mmorgan32]

Originally Posted by Keith Seymore

No.

Rock Auto will have the right one, too. I've ordered three within the last couple weeks for different projects (drum/drum), and you could pay a couple extra bucks and have it overnight.

K

Totally forgot about rock auto. Thanks man that's what I needed to know

[MagmaJct]

A bad master cylinder will lead fluid back into the reservoir.

Imagine a single circuit master cylinder for a moment. A hole in the bottom of the reservoir allows fluid to enter the cylinder ahead of the piston. When the brakes are applied, the piston moves forward, forcing the fluid into the metal lines. During this operation, the piston moves past the hole to the reservoir. The fluid will then leave the reservoir through the same hole and drain into the area behind the piston.

That fluid would drain out the back of the master cylinder, if it weren't for a second piston! So, there's a second piston situated behind the first. It won't/can't pass the hole to the reservoir, because it's far enough back.

When the first piston seal wears enough, it'll allow fluid to leak behind it were it'll then be between the two pistons, and it'll then flow back up into the reservoir through the hole. A leak, without a leak!

So a single circuit master cylinder has two pistons and two seals. A dual circuit master cylinder has double that.

I'm a manufacturing technician, so I've rebuilt plenty of pneumatic and hydraulic cylinders. Rebuilding my truck's master cylinder was not difficult at all. The only caveat is that the cylinder isn't pitted or scored. Mine was pitted a bit, but when I measured where the pitting was, I discovered it was not where the pistons travel.

Once I pulled the old seals, which were still very pliable, and compared them to the new, I could see why my brake pedal would sink to the floor at red lights when I was applying little pressure. The OD of the seals were considerably less than the new seals from the decades and miles of wear.

The rebuilt master cylinder bled easily, and the brakes have not had a single problem since I rebuilt it about a year ago.

Regards,
Mike

[Mmorgan32]

Originally Posted by MagmaJct

A bad master cylinder will lead fluid back into the reservoir.

Imagine a single circuit master cylinder for a moment. A hole in the bottom of the reservoir allows fluid to enter the cylinder ahead of the piston. When the brakes are applied, the piston moves forward, forcing the fluid into the metal lines. During this operation, the piston moves past the hole to the reservoir. The fluid will then leave the reservoir through the same hole and drain into the area behind the piston.

That fluid would drain out the back of the master cylinder, if it weren't for a second piston! So, there's a second piston situated behind the first. It won't/can't pass the hole to the reservoir, because it's far enough back.

When the first piston seal wears enough, it'll allow fluid to leak behind it were it'll then be between the two pistons, and it'll then flow back up into the reservoir through the hole. A leak, without a leak!

So a single circuit master cylinder has two pistons and two seals. A dual circuit master cylinder has double that.

I'm a manufacturing technician, so I've rebuilt plenty of pneumatic and hydraulic cylinders. Rebuilding my truck's master cylinder was not difficult at all. The only caveat is that the cylinder isn't pitted or scored. Mine was pitted a bit, but when I measured where the pitting was, I discovered it was not where the pistons travel.

Once I pulled the old seals, which were still very pliable, and compared them to the new, I could see why my brake pedal would sink to the floor at red lights when I was applying little pressure. The OD of the seals were considerably less than the new seals from the decades and miles of wear.

The rebuilt master cylinder bled easily, and the brakes have not had a single problem since I rebuilt it about a year ago.

Regards,
Mike

Thanks for all the info man I appreciate it.

[Mike_The_Grad]

Well,it seems I'm in need of a new master cylinder. The info here has helped me finalize my decision. Only question I have really is: reman or new? I can get a new AC/Delco unit for $47,or a reman for $27+$20 core. And I'm assuming that overhauling my original may take an indeterminate amount of time because I don't know how bad the inside of my original is. I just replaced my booster about 2 weeks ago and now I can clearly see a drip trail from the rear of my disc/drum master cylinder at the point where it bolts to the booster. And I'm also facing some low pedal,sponginess, loud squealing, and pedal fade at a red light. I just hope I caught it in time to spare my new booster......

[luvbowties]

I'd buy new, w/o thinking. But I'd think twice before paying a big, extra cost for an AC-Delco. Other, cheaper brands just as good. My 2 cents!
Sam