I took my car to a Indy shop to replace brakes on all 4 wheels and master cylinder since it had been acting up.

Prior to taking to shop it always shut down with key.

After shop replaced master cylinder it would no longer shut down at shop on key.

The fellow unscrewed the fitting at vacuum booster and put gauge there and checked vacuum source at this location and it was good and he said at 20 inches + and with this hose plugged and not connected to vacuum assist unit, big black thing, the engine shut down with key so vacuum lost at vacuum assist unit.

He and I looked for any jarred loose hoses and found none. We looked 6 times easy.

He and supervisor mentioned that this can happen but is rare.

The supervisor asked me if the one on there had been changed since it had an ATE tag on it, I said no. I see ATE is OEM so what is on there looks original and could be on there since 1982. He asked in case it had warranty is all but it did look OEM to me for sure.

So they ordered and new or rebuilt one for $187. not sure of brand but I think NAPA sourced, didn't ask.

Anyway I asked if the gasket at base of master cylinder could cause leak they said no because vacuum is sealed before getting to this gasket.

I'd like to know what you all thought about this and had any input.

Car is in shop till next Tuesday when part gets in then it will be installed.

I have had no complaints with work done there before just asking here for some help that the mechanic and I over looked.

Steve

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1982 300SD