Yellow School Bus Breakdown

gmc
vandura

#1

Hello!



Me and my wonderful wife were driving our 1993 GMC 3500 HD Vandura/short bus back from a gig(we are musicians so this big yellow hunk o junk made sense) and started feeling a lot of resistance from the wheels.



We tried to power through as we were in a tunnel underneath Boston toward the Zakim bridge but soon found ourselves dead in our tracks. We managed to pull over in a breakdown lane after an exit but the car would move no further.



We were towed out of the tunnel and onto a public road just outside of Sullivan Station where we decided to take the T home and deal with it the next day.



When I returned the following day there was a large pool of coolant underneath and a small pool of oil.



The van also started right up and towed home just fine. I drove the van to a shop where a busy repair man reluctantly took a look at it and said the water pressure was fine and the coolant was not leaking.



On the way to another shop I started to feel some resistance like before and pulled over. The brake was hard as a rock and all sorts of pressure seemed to be building up,

then a small pool of coolant leaked out followed by a few drops of oil.



I let the car sit for about an hour and started it up. NO hard break or leaks.

I got it back home and am trying to decide a course of action for this cursed little school bus.



Any ideas CarTalkers?


#2

If the brake master cylinder or brake booster were recently replaced the mechanic failed to check and adjust the clearence between the master cylinder piston and the booster push rod. Get it to a good shop soon, though. Whatever the problem it’s dangerous.


#3

Yes the master cylinder was replaced a week and a half ago!


#4

Since there’s conflict over whether this thing is leaking coolant, oil, or whatever about all I’ll venture to guess is that maybe the brake fluid is expanding due to heat and causing the brakes to drag, which could then lead to overheating, which could then lead to coolant puking over…

As mentioned, the pushrod clearance on the master cylinder could be an issue and heated brake fluid could make the situation even worse.
If this problem only started after the MC replacement then that’s what the finger might point at.

Just curious, but where was the engine temperature gauge during all of this?


#5

The dragging brakes cause the engine to labor and over heat.


#6

I agree, and just to expand:

The engine began to overheat, and the very hot coolant overflowed the reservior, spilling excess to the pavement. Excess heat also caused the oil to thin way out and either back it’s way through the crankcase breather line or an old seal somewhere. It is NOT a good idea to try to push the van through dragging brakes. Brakes are more powerful that the engine.