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Discussion Starter · #1 ·

Having a hydroboost problem "brake hang" when its been running. I problem thats been posted a few times from what ive seen. But i think a new post might help me more as ive gotten a seemingly unique situation compared to other previous posts, and a potentially compounded problem.

So i guess ill start with the vehicle
1986 bluebird 22ft bus on an originally 1984 P30.

It originally had a N/A 6.2 which as I was told was swapped for an N/A 6.5 in 93 (paint pen markings on air cleaner and the stamp i saw on the block corroborate when i looked under the doghouse last)

The brakes started locking up
And some supposed experienced diesel tech told me to replace the booster

Which i did myself as it didnt seem like a hard job, but i didnt know the rod was removeable and Oriellys screwed me with arbitrary company policies, including not wanting to pull it from the core sitting at their hub, and not allowing me to go to their hub and retrieve it myself in any capacity.
So i had a machinist help me with a kit from ebay including both washers and the spring. We measured from conact point inside the booster to flush with mating surface - the mating surface on the master cylinder to contact point that sits inside the booster as it itself is inside a lip, im sure experience folx already know that, but moving on. I feel the machinist got the cut and shape fine as it went back together but it didnt sit necessarily flush before i wrenched it down.

I replaced all four hoses
There doesnt seem to be any leaks at all

And my father didnt listen to me and tried to drive it and burned my calipers up, so i replaced all 4

Its still hanging on me

Someone said to use some washers on both the studs between MC and boost, if the issue doesnt go away its the MC

Anyone have any opinion or facts they wanna throw me thatd be cool

I guess i should ask if the proportioning valve can be a culptrit?

Or if clogging in the power steering/braking system can be a thing? The fluid was definetly very old and bad.
The reson for the last question is the bus now pulses a squeal when turning left or right.

Thanks for your time and any help for a detroit newb in advance.

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1995 Chevrolet Silverado Z71 6.5 TD
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When I replaced my hyd booster on my 95 k1500 the rod was not removable. The distance is critical to not having brake lockup or no brakes. Your new hyd booster should have come with one if it did not then I would return it. Maybe on a 1986 bluebird it might be different. I'm sure someone here will know.
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