Brake flush bubble problem
#1
Brake flush bubble problem
I just fully flushed out the brakes on the XK8, they were a little bit spongy after the rear end rebuild. Fronts went ok but when bleeding the back I was getting an almost continuous stream of bubbles from both sides even after flushing a pint of dot4 through each side.
The fluid filling/top up was done with a Sealey VS820.
There were enough bubbles to fill a balloon so I scratched my head, and went back in doors to do some research.
It turns out if the bleed screw is too loose the siphon effect of the fluid draining from the bleed screw can draw air down the threads of the bleed nipple and into your drain line. Problem solved, I thought I would post my experience here in case anyone else comes across this.
The brakes now feel great!
The fluid filling/top up was done with a Sealey VS820.
There were enough bubbles to fill a balloon so I scratched my head, and went back in doors to do some research.
It turns out if the bleed screw is too loose the siphon effect of the fluid draining from the bleed screw can draw air down the threads of the bleed nipple and into your drain line. Problem solved, I thought I would post my experience here in case anyone else comes across this.
The brakes now feel great!
#2
The following 5 users liked this post by astromorg:
Jim D (10-05-2015),
Johnken (09-29-2015),
RaceDiagnostics (09-30-2015),
rocklandjag (10-01-2015),
VinceCh (04-04-2016)
#3
I wasn't aware of this but after doing some research I tried lifting the jar above the nipple and the bubbles immediately stoped.
#4
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RaceDiagnostics (09-30-2015)
#5
That is the reason I spent the $45 on a pressure bleeder. It makes a half hour job a 10 minute job, and with better results. Pump it up to around 10 psi, and start on the furthest wheel from the master cylinder, and then move from wheel to wheel getting closer to the master. It uses about half the fluid, keeps damage to the master to a minimum, and if you use a pan there is absolutely no mess.......Isn't your time worth at least $45....Be cool....Mike
#6
That is the reason I spent the $45 on a pressure bleeder. It makes a half hour job a 10 minute job, and with better results. Pump it up to around 10 psi, and start on the furthest wheel from the master cylinder, and then move from wheel to wheel getting closer to the master. It uses about half the fluid, keeps damage to the master to a minimum, and if you use a pan there is absolutely no mess.......Isn't your time worth at least $45....Be cool....Mike
Also read the jag workshop manual, it says start with the closest wheel!
The following users liked this post:
multiplecats (04-04-2016)
#7
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#9
I don't know why it is suggested to go to the front wheel, with a Jag, but almost every other car on the planet is bled from the furthest wheel first. I guess that is why Jags are special. I got bubbles out of the rear wheels, and hardly any out of the front wheels. Porsche, VW, Audi. Mercedes, BMW, and Rolls Royce bleed from the furthest wheel first. Also, after bleeding the back wheels first, you slowly pump the brakes, until you get a reasonable pedal, or the ABS unit will give you every bit of air out of that block it can......Be cool....Mike
Last edited by mrplow58; 09-30-2015 at 09:10 PM.
#10
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The following users liked this post:
multiplecats (04-04-2016)
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