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Brake vacume issue fix

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Brake vacume issue fix

Postby Dadley » Tue Oct 11, 2016 6:02 am

Hey team,

Recently had an issue with my brakes that is now sorted, but could not find any info on someone having similar symptoms so thought I would share in case someone ends up in the same spot and comes looking for help.

On start up the brake warning light would come on (indicating lack of vacuum). However in most cases if the car was driven for about 100m the brakes would sort themselves out and the light would turn off and the system was fine until turning the vehicle off. How annoying this was would fluctuate sometimes it would be sweet by the time I pulled out of the driveway, other times it would stay out of vac until 20min later.

I checked the hoses and thought it was a faulty vac pump as getting the revs up usually helped, but when I tested that it and it was fine. I replaced the hoses and put one with a check valve in just to make sure the system was set up properly. I also changed the wee solenoid at the bottom of the brake booster... Fixed, for about 3 starts and then the problem returned and gradually got worse.

Ended up being the brake booster itself, swapped that out, bled the brakes and boom, its awesome now. Assuming that that Diaphragm has a break in its seal, but no real clue.

They fix itself seemed pretty systematic (following instructions found on here as per what to check). Just had not seen anyone with the same symptoms so here we are. Hopefully makes life easy for someone in the future. Cheers.
Mud hides the scratches

93 LWB Bighorn

2 Inch spring Lift, wound torsions, 31s, snorkel, egr blanked, hi flow intake, thousands of dents and scratches... just an adventurous daily really.
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Re: Brake vacume issue fix

Postby geeves » Tue Oct 11, 2016 11:23 am

It has come up before but not as a topic on its own. Rob has fixed a few with that problem.
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Brake vacume issue fix

Postby JenHowells » Thu Feb 16, 2017 7:04 am

Hi,

We've been told that the brake servo (I presume 'brake booster' is the same thing) needs replacing on our '91 Trooper 2.8TD (UBS55), we've been having trouble with the brakes - fine under 'normal' driving conditions but in an emergency stop situation they go solid.

Does anyone know of a source for these? The only one I've found so far is 2nd hand from Germany.

What else should I confirm that they have checked? The vacuum hose..?

cheers
Jenny
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Re: Brake vacume issue fix

Postby geeves » Thu Feb 16, 2017 2:22 pm

in your emergency stop are you cadence braking or one big push?
Cadence trys to simulate abs and can help in slippery conditions but the Diesel pump doesnt really provide enough vacuum for more than about 5 presses. Before changing the booster check all the hoses for leaks and fit a non return valve as close to the servo as possible. This helped a lot on my wizard but was probably masking the real fault. The later diesel troopers had a reserve vacuum tank which might also help.
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Brake vacume issue fix

Postby JenHowells » Thu Feb 16, 2017 7:39 pm

Thanks geeves.
Personally, one big push - but I can't speak for my husband or the guy at the garage.
He has checked the hoses and will have a chat to him about other possibilities.
cheers
Jenny
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Re: Brake vacume issue fix

Postby Dadley » Sun Apr 02, 2017 3:56 pm

Mine lost vacuum and went firm i pumped them and sometimes if I did one big push. I just replaced the whole brake booster, found a second hand one cheap online. Hope you got it fixed. :D
Mud hides the scratches

93 LWB Bighorn

2 Inch spring Lift, wound torsions, 31s, snorkel, egr blanked, hi flow intake, thousands of dents and scratches... just an adventurous daily really.
Dadley
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Joined: Tue Sep 20, 2016 4:22 pm
Location: Christchurch, NZ
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Country: NZ
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Vehicle: 93 LWB Bighorn

2 Inch spring Lift, wound torsions, 31s, snorkel, egr blanked, hi flow intake, thousands of dents and scratches... just an adventurous daily really.

Re: Brake vacume issue fix

Postby 17brno » Sun Oct 15, 2017 1:56 pm

Hi there 92 bighorn ubs69 owner I have the same problem with the handbrake warning light staying on and then some times going off
(The other day I took it for a WOF and it failed because the light stayed on, when I started the truck to go home the light was off :evil: )
I have replaced the rear rotors and pads and the front rotors and pads as well, I have checked the handbrake switch ,brakefluid level and that the float isn't jammed and cleaned the plug for the float switch I also removed the hose from between the vacuum tank and the rear of the alternator and it sucks air
What else can I check?
Brakes seem fine when i apply them
Thanks Ivan
Last edited by 17brno on Sun Oct 15, 2017 6:35 pm, edited 1 time in total.
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Re: Brake vacume issue fix

Postby geeves » Sun Oct 15, 2017 4:11 pm

there is a vacumm sensor as well
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Brake vacume issue fix

Postby 17brno » Sun Oct 15, 2017 6:39 pm

Hi there where abouts is the vacume senser located
Thanks Ivan
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Re: Brake vacume issue fix

Postby geeves » Mon Oct 16, 2017 4:36 am

I think its the sensor on the booster
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Brake vacume issue fix

Postby 17brno » Mon Oct 16, 2017 7:07 pm

I have removed the senser from the booster, that was a fun job and tested it and it appears to be faulty so the next question is are the sensers readily available and where would i get one from
Thanks Ivan
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Re: Brake vacume issue fix

Postby 17brno » Fri Oct 20, 2017 6:26 pm

Got a 2nd hand senser for $15 ($150.00 new I was quoted) installed it and problem solved, got wof and rego today :D
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