bj70 brake and starter problem (1 Viewer)

Joined
Apr 25, 2007
Messages
674
Location
S.CA - N.OC - Fullerton
 
 
When I got this thing the brakes seemed to work pretty well but the light was coming on here and there. It got where I had to pump it to get it to stop affirmatively so I assumed it was the MC.

I recall that it didn't seem like the normal MC symptoms I have seen in the past. At first pumping it seemed to help but later it didn't. I don't really remember because it was over a month ago since I drove it.

Anyway, I changed the MC and I don't thing it did anything. It does have some brakes but it's very soft feeling- then when you try to pump it it seems to have less brakes on the second press. The light comes on when pressing down.

Is this possibly a slow leak in the booster? It's pretty strange to me.

Any help would be greatly appreciated.

Also, the starter solenoid clicks most of the time and occasionally cranks. I'm wondering if you can buy the solenoid separately as I know the starter is expensive-- or, are there any quick fixes?
 
Joined
Sep 28, 2002
Messages
8,018
Location
Vancouver Island BC Canada
 
 
 
 
Most likely your back brakes are very badly adjusted and the parking brake pivots at the backing plates are not resting on the backing plates.

Check that first and foremost, then go after other things.

Starter solenoid contacts and plunger is what you're after... very common service item.


~John
 
Joined
Sep 6, 2002
Messages
3,588
 
 
 
vacuum res could have rusted through!
No, then the brakes would be hard, not spongy. similarly with the booster, if you lack the boost your brakes would be super hard.

Check the rear brakes, as has been said. Also, your front wheel bearings could be really loose, therefore the front caliper piston travel gets too big.

Adjust the rears, check the front wheel bearings for tightness, and take it from there. I assume you have no fluid loss...

cheers,
Jan
 
Joined
Apr 25, 2007
Messages
674
Location
S.CA - N.OC - Fullerton
 
 
I thought for sure you nailed it but the rear shoes are not out of adjustment. They are down to about 10% linings though. I'm thinking that with new rear linings (and the drums maybe turned out to the max), that will bring the pedal up. I tested it with a hard stop and it did stop pretty well so it seems like the new MC did something but maybe it's just my imagination. When I stopped real hard sometimes the light didn't come on- I don't know if that means anything or not. I was wondering about the booster too and even more now. Tomorrow I'll do a test on it. Any other ideas? Thanks for the advice and to the gent who mentioned the booster.
 
Joined
Apr 25, 2007
Messages
674
Location
S.CA - N.OC - Fullerton
 
 
No, then the brakes would be hard, not spongy. similarly with the booster, if you lack the boost your brakes would be super hard.

Check the rear brakes, as has been said. Also, your front wheel bearings could be really loose, therefore the front caliper piston travel gets too big.

Adjust the rears, check the front wheel bearings for tightness, and take it from there. I assume you have no fluid loss...

cheers,
Jan
No fluid loss. I'll check the bearings tomorrow. BTW, does anyone know what that (valve?) is in the rear brake circuit is that is actuated by the rear axle movement?
 
Joined
Sep 6, 2002
Messages
3,588
 
 
 
No fluid loss. I'll check the bearings tomorrow. BTW, does anyone know what that (valve?) is in the rear brake circuit is that is actuated by the rear axle movement?
Load sensing valve. It directs more pressure to the rear when the truck is heavily loaded and the axle and frame are closer together in height.
cheers,
J
 

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