 | Home > Puma (Tdci) > Squishy brakes after Brake Master Replaced (NO ABS) |
 
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| dannyragsdale Member Since: 06 Oct 2022 Location: Eastern Highlands, PNG Posts: 40   
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So I replaced my brake mastery cylinder over a month ago because my brakes would get squishy about a week or two after bleeding. Well, after replacing the brake master cylinder, it lasted about a month before they got squishy.
I have searched all over and can't find any leaks anywhere and I'm not losing any fluid from the reservoir. Not sure where else to look. Any suggestions? Thanks for any help or suggestions! |
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10th May 2023 8:12am |
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| geobloke Member Since: 06 Nov 2012 Location: Nottinghamshire Posts: 4410 
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How are your wheel bearings? If not correctly adjusted it can feel as if there is more pedal travel before the pads bite.
How are the bleed nipples? These can fail and draw in air leading to squishy brakes. Check all unions and flexi hose crimps. |
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10th May 2023 11:04am |
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| dannyragsdale Member Since: 06 Oct 2022 Location: Eastern Highlands, PNG Posts: 40
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I've recently done the front wheel bearings. This was a problem before doing them too.
I'll have to check the bleeders. Thanks for the recommendations. |
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10th May 2023 1:12pm |
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| geobloke Member Since: 06 Nov 2012 Location: Nottinghamshire Posts: 4410
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No problem. Check your bearings again. If you are old stool then you would have used the two nuts and tab washer method, rather than the TD5 era single big nut. The older versions need to be checked periodically after initial fitment as the bearings will loosen as they bed in.
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10th May 2023 1:17pm |
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| geobloke Member Since: 06 Nov 2012 Location: Nottinghamshire Posts: 4410
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Good call Blackwolf.
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10th May 2023 3:19pm |
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| dannyragsdale Member Since: 06 Oct 2022 Location: Eastern Highlands, PNG Posts: 40
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I'm leaning towards it not being bearings. The fact that I can bleed them and they're better for 2-4 weeks says it's something else. It's a slow progression too. They'll be perfect right after bleeding but then start noticing after a week or so that they start being squishy and then after another 2-3 weeks, the pedal will go all the way to the floor. I can pump the pedal and get pressure, but the initial pump is straight to the floor.
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10th May 2023 9:21pm |
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| BaCoNMX6 Member Since: 22 Apr 2022 Location: Amsterdam Posts: 63 
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That sounds like some sort of air leak in the system. Perhaps a pin-hole in one of the lines or one of the connections having a hairline crack/leak.
Probably already done this but a thorough visual check on all lines might show something? |
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11th May 2023 2:30pm |
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| dannyragsdale Member Since: 06 Oct 2022 Location: Eastern Highlands, PNG Posts: 40
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Headed to the shop in a little bit and put it on a lift and do another thorough check over. There's gotta be some small leak somewhere.
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11th May 2023 11:06pm |
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| dannyragsdale Member Since: 06 Oct 2022 Location: Eastern Highlands, PNG Posts: 40
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So I got it on the lift and removed all 4 tires so I could get a good look at everything. So my brake system is the brake master (no proportional valve) and lines directly right front, left front, and a single line that splits at the back for both rear brakes.
So I had my buddy get in and pump the brakes until it was completely solid and then I went around to the three rubber brake lines and clamped them. That way things were more isolated and I could hopefully figure out where the problem was. Hopefully 
I came back after 3 hours and everything was still solid. No brakes had freed up whatsoever and the brake pedal was still solid at the top. Did another thorough inspection hoping something would finally leak by after 3 hours of full pressure. But alas, nothing. I then unclamped everything and started bleeding at each caliper. The only one with air was the front left, and that one was my least suspicious one! I have no idea where the air is getting in! I guess I'm going to give it another few weeks until it gets squishy again and see if something changes. Thanks again for all the help. |
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12th May 2023 6:27am |
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| geobloke Member Since: 06 Nov 2012 Location: Nottinghamshire Posts: 4410
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Ok, so front left that is a start. I would suspect the flexi pipe of bleed nipple is drawing air in as the braking pressure and fluid temperature decreases after use. Begin by whipping the bleed nipple off and making sure the thread and mating surfaces are clean and capable of making a good airtight seal. As for the flexi pipe... If I were you I would be swapping all three of them out for a set of braided hoses. Yes it is throwing parts at the problem but sometimes it is the only way to begin discounting problem areas.
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12th May 2023 9:22am |
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| dannyragsdale Member Since: 06 Oct 2022 Location: Eastern Highlands, PNG Posts: 40
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It's really hard to start throwing parts at things being in Papua New Guinea. Depending on what it is, shipping can add 30%-50% more to what I am buying. I already did that with the with the brake master cylinder and I'm hoping to have a more definitive answer before I start buying more things.
That being said, your idea of the bleed screw drawing air in after fluid temperature dropping makes a lot of sense. I mostly do very short drives, but it seems to get way worse after I do a drive more than 30 minutes. So I will be buying bleeding screw for all 4 brakes next time I make an order. If that doesn't fix things, then I'll venture into the new braided brake lines. |
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14th May 2023 1:01am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17387 
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I don't really see how air could be drawn in without fluid also being able to leak out, since the pressure differential with the brakes off is effectively nil but will be several hundred PSI during a brake application.
Generally if there's a problem like this with no loss of fluid the fault lies within the master cylinder or possibly servo. What make of master cylinder did you fit? The fact that changing the master cylinder fixed the problem for a month is also suggestive perhaps. |
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14th May 2023 7:17am |
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| Dinnu Member Since: 24 Dec 2019 Location: Lija Posts: 3414  
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I had exactly that on my old 90. It is the non return valve in the master cylinder, allowing the brake fluid to go in the reservoir. If its an aftermarket master, then I would be weary about the quality of the rubber used. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing 2012 90 CSW, 2.2TDCI, Santorini Black |
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14th May 2023 7:40am |
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| dannyragsdale Member Since: 06 Oct 2022 Location: Eastern Highlands, PNG Posts: 40
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I installed a Britpart brake master and I already know what you're going to say about it
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After thinking about it, I hadn't done any driving other than a few minutes a day the month after I replaced the brake master. Then once I had done a decent trip, it got spongy again. |
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14th May 2023 7:47am |
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