80 Series - Chev 6.5L Brake problem

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Mike Amen
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Joined: June 22nd, 2003, 2:48 pm
Location: Dianella WA

80 Series - Chev 6.5L Brake problem

Unread post by Mike Amen » August 17th, 2015, 8:10 pm

Hi All
I have an 80 Series with a Brunswick converted Chev 6.5L.
It's been perfect until last week when I started to get a hard brake pedal. It's fine after driving or reving, but after applying the brakes a second or third time the pedal goes rock hard and has no vacumm assitance from the booster. I thought it was the vacuum pump, but after replacing that it's still the same. I've check all of the hoses, check valves and pipework and it all seems fine. Due to the motor being so loud I can't hear if there's a vacuum leak anywhere. And since it's an independant vacuum circuit (vacuum pump, not manifold vacuum) spraying a bit of arostart wont give any clues either. I'm guessing it may be the booster, but I don't want to keep replacing parts on the off chance.
Has anyone come across this before? If so I'd like some advice please.

Shann Low
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Posts: 765
Joined: April 2nd, 2014, 3:14 am

Re: 80 Series - Chev 6.5L Brake problem

Unread post by Shann Low » August 17th, 2015, 9:50 pm

I was gonna say leak in the booster!
Any way you can pull a vacuum on the booster and see if it holds?
I'm down the road from you (Morley) and have a Thomas vacuum pump on Effie that is for the brake away towing brakes (so has vacuum outlets at the rear for the trailer brakes). Maybe we run a hose from the rear of mine to your booster and see if it holds vacuum or leaks down? Just a suggestion. If it leaks down, the vacuum pump sense the vacuum drop and will kick in again.
Dunno if there's an easier way?

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