Blue-Truck-Nut97
crank polisher
- 551
- 18
So here's a noggin scratcher-
Vehicle in question is a 1965 F-850, Napco Powr-Pak 4x4, fire truck. 534 V8, 5 spd direct. (1000 gallon tank, pump and roll, pretty sweet setup.) Truck has vacuum assist brakes, with the vacuum booster unit remote mounted under the drivers running board.
Truck sees seasonal use, we keep it running, and it's full of water in the summertime for fire prevention, tree watering, and trailer wash outs. As goes with most vehicles with hydraulic brakes that sit a lot, I usually have to bleed them once a year or so. About 2 years ago I changed the master cylinder when it developed a leak. Not much else to report.
Here's the puzzle, washed out a trailer a couple days ago, truck was sitting running powering the pump, I walked around back stretching the hose out and noticed the brake lights on. Hmmmm, bad switch apparently, but alas, it can't be that simple. Got in the truck to park it, and the brake pedal was hard as a rock, and the brakes were locked. By shutting it off and bleeding the vacuum off, they would release. Drove it back in the yard, brakes were getting tight by the time I got parked. Again, shut it off, bled off vacuum in the reservoir, and they released.
Initially, I thought the booster was failing, but, it never sucked all the brake fluid into the intake like they usually do.
AND
The hard brake pedal, all toe board clearance is gone now, pedal comes up hard against the stop. I distinctly remember having 3/16"-1/4" when I put the master cylinder on. So after studying on it, I'm wondering about that master cylinder. I'm thinking about cracking the line on the master and seeing if they release next time it's running.
Anybody seen this before?
Thoughts or suggestions?
Know a good exorcist?
Sent from my E6810 using Tapatalk
Vehicle in question is a 1965 F-850, Napco Powr-Pak 4x4, fire truck. 534 V8, 5 spd direct. (1000 gallon tank, pump and roll, pretty sweet setup.) Truck has vacuum assist brakes, with the vacuum booster unit remote mounted under the drivers running board.
Truck sees seasonal use, we keep it running, and it's full of water in the summertime for fire prevention, tree watering, and trailer wash outs. As goes with most vehicles with hydraulic brakes that sit a lot, I usually have to bleed them once a year or so. About 2 years ago I changed the master cylinder when it developed a leak. Not much else to report.
Here's the puzzle, washed out a trailer a couple days ago, truck was sitting running powering the pump, I walked around back stretching the hose out and noticed the brake lights on. Hmmmm, bad switch apparently, but alas, it can't be that simple. Got in the truck to park it, and the brake pedal was hard as a rock, and the brakes were locked. By shutting it off and bleeding the vacuum off, they would release. Drove it back in the yard, brakes were getting tight by the time I got parked. Again, shut it off, bled off vacuum in the reservoir, and they released.
Initially, I thought the booster was failing, but, it never sucked all the brake fluid into the intake like they usually do.
AND
The hard brake pedal, all toe board clearance is gone now, pedal comes up hard against the stop. I distinctly remember having 3/16"-1/4" when I put the master cylinder on. So after studying on it, I'm wondering about that master cylinder. I'm thinking about cracking the line on the master and seeing if they release next time it's running.
Anybody seen this before?
Thoughts or suggestions?
Know a good exorcist?
Sent from my E6810 using Tapatalk
