My 87 HB30 Diesel Coaster has suddenly developed an issue with loss of brake vacuum. Has any member experienced this problem.
I assume that the brake booster diaphragm is at fault but understand that a faulty PCV valve can also be a cause. The Bus has brakes with
the engine running and loses vacuum when not with a resulting hard pedal. Any ideas?
Thanks Steve
with
blaze said
08:39 AM Feb 1, 2015
Hi steve
You will have a small vac tank and a vac pump (maybe on the back of the alternator), if you have vacuem when the engine is running then I suspect a leak. The leak could be in any of the vac hoses or the brake booster. Often the ends of the vac lines split where they connect and just trimming them off and refitting may solve the problem
cheers
blaze
mr glassies said
05:49 PM Feb 1, 2015
what blaze said . i have a nissan condor tipper it sometimes it shows a brake problem and i found a split vac line caused it but sometimes you have to look hard for the offending one mine was a small one about the dia of a smoke . or it could be a low brake fluid warning or a worn out linings
dibs
justcruisin01 said
07:21 PM Feb 1, 2015
Like said most likely hoses; check all hose connections between the pump & tank & booster for cracking . These hoses can also block internally from a bit of oil deteriation of the rubber.
Another problem can come from the alternator.
Have you had the alternator serviced lately?
When they remove the vacume pump the old oil seal can be damaged & cause lose of vacume.
-- Edited by justcruisin01 on Sunday 1st of February 2015 07:51:53 PM
Solo Steve said
08:13 PM Feb 1, 2015
Thanks everyone for the tips. The Vacuum tank has some surface rust so may have a small hole somewhere. I also suspect a hose problem.
I topped up the fluid and that didn't help. There are no obvious leaks anywhere. I will be putting the Bus in a workshop this week and will pass on your advice
I will post the result thereafter.
Cheers Steve
landy said
09:59 PM Feb 1, 2015
Just a thought and I am quite happy to be shot down if there is a fault in my thinking ,but is it posible to put a low positive presure in the line ( maybe 15 ; 20 psi ) and then test with soapy water.
Landy
Solo Steve said
08:00 PM Feb 5, 2015
For those that are interested this problem has been solved. There is a sensor switch at the front of the auxiliary vacuum tank and it was faulty
and leaking. Luckily the repairer found a new one in Melbourne somewhere. Thanks for all the suggestions they were not far off the mark.
My 87 HB30 Diesel Coaster has suddenly developed an issue with loss of brake vacuum. Has any member experienced this problem.
I assume that the brake booster diaphragm is at fault but understand that a faulty PCV valve can also be a cause. The Bus has brakes with
the engine running and loses vacuum when not with a resulting hard pedal. Any ideas?
Thanks Steve
with
You will have a small vac tank and a vac pump (maybe on the back of the alternator), if you have vacuem when the engine is running then I suspect a leak. The leak could be in any of the vac hoses or the brake booster. Often the ends of the vac lines split where they connect and just trimming them off and refitting may solve the problem
cheers
blaze
dibs
Like said most likely hoses; check all hose connections between the pump & tank & booster for cracking . These hoses can also block internally from a bit of oil deteriation of the rubber.
Another problem can come from the alternator.
Have you had the alternator serviced lately?
When they remove the vacume pump the old oil seal can be damaged & cause lose of vacume.
-- Edited by justcruisin01 on Sunday 1st of February 2015 07:51:53 PM
Thanks everyone for the tips. The Vacuum tank has some surface rust so may have a small hole somewhere. I also suspect a hose problem.
I topped up the fluid and that didn't help. There are no obvious leaks anywhere. I will be putting the Bus in a workshop this week and will pass on your advice
I will post the result thereafter.
Cheers Steve
Landy
For those that are interested this problem has been solved. There is a sensor switch at the front of the auxiliary vacuum tank and it was faulty
and leaking. Luckily the repairer found a new one in Melbourne somewhere. Thanks for all the suggestions they were not far off the mark.
Steve