Locked brakes

[reblawyer]

I just got my first deuce and am a newbie to this site; please be gentle. From what I can tell, the brakes are air over hydraulic. When the valves to the air system are closed and pressure builds up in the tanks the brakes lock up ( the brake lights even come on). Any thoughts on what my problem is and how I can approach a repair?

 

[Boatcarpenter]

More than likely, the problem is in the operation of the airpack. My understanding is that when it fails, one of two events occurs. You either have no brakes( or maybe hydraulic only) or they lock up. They lock up because the large piston and the valveing in there is allowing air pressure through to the hydraulic side all the time, applying the brakes and actuating the brake lights. This may or may not be your trouble, but I would perform an airpack rebuild or at least an inspection and cleaning at the least. Mine locked when I came to a stop in my driveway(fortunately) and a thorough cleaning and lubing of the airpack fixed the problem. Hope this is a good starting point.

 

[BFR]

By the way I would add your location to your sig you may find you are close to other members who can help trouble shoot in person.

 

[reblawyer]

I think I've gotten the location info added. I'll take a stab at the air pack this weekend.

 

[reblawyer]

That isn't quite what I expected.

I just finished pulling down and cleaning the airpack. The rear end is still locking up when the pressure builds. I noticed that the piston is releasing VERY slowly after being depressed. Any thoughts?

 

[WillWagner]

There are a couple of check valves in there, are they clear? Saturn has complete rebuild kits for way cheap. I think it's easier to just take it all the way down and start fresh, you'll be able to drive it sooner!

 

[reblawyer]

I tried to find the kits on the Saturn website but couldn't locate them. Do they have a catalog or something?

 

[Boatcarpenter]

Try this link
http://www.saturnsurplus.com/m35/m35-4.htm

Scroll down to Hydrovac rebuild kit

 

[Recovry4x4]

I got a rebuild kit from KCGONZO on Ebay. He's listed quite a few. Got mine for around $20.

 

[WillWagner]

You can just call Saturn, he'll know the P/N. Just be aware, the kits are NOS, they're old. I tried to order them from Midland and they kind of laughed at me, but the paper gaskets are hard as a hookers heart, just get way hot water, and let them soak for a bit, they'll go back to their original shape and size and they'll be good as new.

 

[cranetruck]

REB, open the glad hand on the driver's side in the rear, this will release the air pressure on the large airpak piston. This is a direct line and will at least release the brakes. The line bypasses the internal valves of the airpak.
You may also have a blocked vent. The airpak vent joins the MC vent and both join the fuel tank vent before finally venting through the crankcase breather. Check it all and make sure there are no kinked lines.