Master cylinder replacement and brake bleeding hasn't fixed a soft brake pedal

[JayOh]

I'm starting to think that this thing is cursed, possibly related to the covid-17 number plate (cvd-17n).. last week I called a jeep dealer and got it booked in for today. Drove 45 minutes yesterday to drop it off in their earlybird parking, took 90 minutes on public transport to get home. Called them this morning to make sure it was all ok and the response was - what booking? FML.

[Fishframe]

Originally Posted by JayOh

I'm starting to think that this thing is cursed, possibly related to the covid-17 number plate (cvd-17n).. last week I called a jeep dealer and got it booked in for today. Drove 45 minutes yesterday to drop it off in their earlybird parking, took 90 minutes on public transport to get home. Called them this morning to make sure it was all ok and the response was - what booking? FML.

Time to trade for the best? A TJ !

[JayOh]

Originally Posted by Fishframe

Time to trade for the best? A TJ !

For a second there I thought you were going to say Patriot..

[Fishframe]

Originally Posted by JayOh

I'm starting to think that this thing is cursed, possibly related to the covid-17 number plate (cvd-17n).. last week I called a jeep dealer and got it booked in for today. Drove 45 minutes yesterday to drop it off in their earlybird parking, took 90 minutes on public transport to get home. Called them this morning to make sure it was all ok and the response was - what booking? FML.

I’ve set my iPhone diary to remind me to check back in on this in the year 3068. 😳

[JayOh]

Originally Posted by Fishframe

I’ve set my iPhone diary to remind me to check back in on this in the year 3068. 😳

I guess that makes you an optimist!

The dealer called this afternoon and told me the first step would be to bleed the brakes, at a cost of an hour's labour and two bottles of brake fluid, but it wouldn't be ready today.

I will be amazed if that fixes the problem, but we'll see what they say tomorrow.

[JayOh]

As expected the brake bleed has made no difference. I'm still unclear as to whether they carried out an abs bleed in addition to the regular bleed.

The next step in their diagnosis is to start replacing parts at my expense to see if this fixes the problem, The recommendation is to do the booster next as the leaking master cylinder is likely to have leaked brake fluid into the booster and contaminated it.

How this is likely to cause a soft pedal I don't quite understand as I'm not a mechanic. When I pump the brakes while stationary with the engine running I can hear a hissing sound like air being squeezed out of something from up behind the dash, I'm assuming it's coming from the booster. I can only think that the brake pedal or booster is not pushing hard enough or far enough on the master cylinder to make the brakes work correctly.

Pumping the brakes does not improve the pedal feel or brake performance.

So now I'm waiting for a quote to replace the booster and I'm assuming it will be outrageous. They previously quoted over $650 for the master cylinder and over 6 weeks lead time to arrive from the US. I managed to source this from Rock Auto for about $220 delivered in less than two weeks. Rock have the booster for $145 or $220 AUD depending on which version it needs.

Let's see what they come back with tomorrow..

[layback40]

Originally Posted by JayOh

As expected the brake bleed has made no difference. I'm still unclear as to whether they carried out an abs bleed in addition to the regular bleed.

The next step in their diagnosis is to start replacing parts at my expense to see if this fixes the problem, The recommendation is to do the booster next as the leaking master cylinder is likely to have leaked brake fluid into the booster and contaminated it.

How this is likely to cause a soft pedal I don't quite understand as I'm not a mechanic. When I pump the brakes while stationary with the engine running I can hear a hissing sound like air being squeezed out of something from up behind the dash, I'm assuming it's coming from the booster. I can only think that the brake pedal or booster is not pushing hard enough or far enough on the master cylinder to make the brakes work correctly.

Pumping the brakes does not improve the pedal feel or brake performance.

So now I'm waiting for a quote to replace the booster and I'm assuming it will be outrageous. They previously quoted over $650 for the master cylinder and over 6 weeks lead time to arrive from the US. I managed to source this from Rock Auto for about $220 delivered in less than two weeks. Rock have the booster for $145 or $220 AUD depending on which version it needs.

Let's see what they come back with tomorrow..

The air sound you hear is normal & suggests the booster is working.
The sinking suggests the master is letting fluid past the pressure seal unless it is loosing fluid.
If it is loosing fluid, find where the loss is occuring.
If it is not loosing fluid, the master is faulty.
Any half decent mechanic or DIY person could tell you that.
Jeep dealers employ kid with no knowledge to do work.