Brakes mystery

Hi all,

Bit of a mystery again. I bled the brakes last week. Today the missus tells me when she went to pick the little one up from school the brake-pedal traveled almost all the way down before working. Did it all the way there and back, apparently. Gave her a bit of a scare.

I went out when I got home: the fluid level was right up to the cap and some had actually forced its way past the cap and leaked. Drove it backwards and forwards a few times to test the brakes. They were fine. Checked the fluid level: it had gone back to normal! Took it for a 15 mile ride using the brakes at every opportunity and throwing a few emergency stops in (traction control definitely works). All fine. Got back and checked it: all fine with fluid on the max. No faults that I can see.

All a bit of a mystery. Obviously time will tell next time the fault lifts its ugly head but given it is the brakes with the wife and kid inside I'd kind of like to pin down what it might be first.

Any ideas welcome.

Cheers,

J

1995 P38A 2.5 DT.

Sounds like master cylinder seals. BUT the Rangey Guru's will send their Butlers out to shed more light on it, shortly.

Looking at the schematic, Pikey could be right, the Master could be liking back into the tank...

The DT is a manual correct?? if so the Brake fluid reservoir also feeds the clutch circuit, so maybe the clutch pedal cylinder is pushing fluid back to the tank rather than the clutch - but doubtful!

poor seals on m/c or clutch m/c can make fluid splash in reservoir but not increase level , you would need a piston to be pushed back to increase level or have accummaltor problems

Yes, it is a manual.

Clutch slave cylinder was replaced when I did the spiral clutch pins a few years back but didn't touch the master.

Accumulator seems to be working fine. Certainly pushed the old fluid out fine. Can hear it when you first turn the key and then it shuts off a few seconds later when it is up to pressure.

Now I think about it the old fluid was VERY dark and seemed to have black stuff in. Could have been the seals, I guess. Is a new master cylinder expensive or can you refurb the old seals easily enough?

Grrrrrr said:

Yes, it is a manual.

Clutch slave cylinder was replaced when I did the spiral clutch pins a few years back but didn't touch the master.

Accumulator seems to be working fine. Certainly pushed the old fluid out fine. Can hear it when you first turn the key and then it shuts off a few seconds later when it is up to pressure.

Now I think about it the old fluid was VERY dark and seemed to have black stuff in. Could have been the seals, I guess. Is a new master cylinder expensive or can you refurb the old seals easily enough?

Click to expand...

refurb kit available as washers can break up as mine did years ago

Sounds like air in the system, did you follow the complicated bleed proceedure correctly? Maybe pump oreation is intermittant.

Following the bleed procedure is essential. Hydrostatic first with no accumulator pressure then pressure system. Fluid must be topped to Max mark and no further after ABS pump has stopped running. Only reason you would get fluid coming out of cap vent is simply because you have over filled it. Fluid bleeds back from accumulator over time that is why there is excessive space in the tank above the Max level. If the car has been stood for a few days expect to see fluid above Max until pump runs, then when it stops fluid should be at or near Max but NOT above it.

wammers said:

Following the bleed procedure is essential. Hydrostatic first with no accumulator pressure then pressure system. Fluid must be topped to Max mark and no further after ABS pump has stopped running. Only reason you would get fluid coming out of cap vent is simply because you have over filled it. Fluid bleeds back from accumulator over time that is why there is excessive space in the tank above the Max level. If the car has been stood for a few days expect to see fluid above Max until pump runs, then when it stops fluid should be at or near Max but NOT above it.

Click to expand...

Correct. Followed instructions in RAVE to the letter. It did end up a bit over the max at the end after it had stood for a while. That caught me out but fortunately I still had the cap off. It seemed to stablise out though. Been OK today apparently. I'm worried about the amount of black stuff that was in the old fluid though. Certainly looked like old seals might be breaking down.

Am I right in thinking the unit comes as a whole with the reservoir on top and seems to cost about £1000?

When I say stood for a while I mean a minutes and hours, not days and weeks. The car is used every day!

Only 2 types? 2 or 4 wheel traction control? No difference between auto and manual box or diesel and petrol?

Grrrrrr said:

Correct. Followed instructions in RAVE to the letter. It did end up a bit over the max at the end after it had stood for a while. That caught me out but fortunately I still had the cap off. It seemed to stablise out though. Been OK today apparently. I'm worried about the amount of black stuff that was in the old fluid though. Certainly looked like old seals might be breaking down.

Am I right in thinking the unit comes as a whole with the reservoir on top and seems to cost about £1000?

Click to expand...

Get one out of a post 99 in the scrap yard - earlier units have some sort of internal valve made from plastic that breaks.

Grrrrrr said:

Correct. Followed instructions in RAVE to the letter. It did end up a bit over the max at the end after it had stood for a while. That caught me out but fortunately I still had the cap off. It seemed to stablise out though. Been OK today apparently. I'm worried about the amount of black stuff that was in the old fluid though. Certainly looked like old seals might be breaking down.

Am I right in thinking the unit comes as a whole with the reservoir on top and seems to cost about £1000?

Click to expand...

The dark colour only appears in the calipers normally. Result of heating over time. But does get pushed back towards the master cylinder when pads are changed. I use one of these to check fluid for moisture. Gunson 77002 Brake Fluid Tester Coloured Response Test Percentage Water | eBay

Grrrrrr said:

Correct. Followed instructions in RAVE to the letter. It did end up a bit over the max at the end after it had stood for a while. That caught me out but fortunately I still had the cap off. It seemed to stablise out though. Been OK today apparently. I'm worried about the amount of black stuff that was in the old fluid though. Certainly looked like old seals might be breaking down.

Am I right in thinking the unit comes as a whole with the reservoir on top and seems to cost about £1000?

Click to expand...

The level always rises when it's stood for a while.

Thanks Steve.

@Wammers: not done the pads or discs. I was going to but my brother needed them to get his through his MOT test and took the lot! There was black in the reservoir too. Wish I'd taken a photo now. Still OK to date.

I've not seen any refurb kits for the P38 in the usual places. Anyone got any ideas there?

here master cylinder kits

rtc5834- Master cylinder - repair kit (Master cylinder - repair kit) - - Land Rover Range Rover 2 (P38) 1994->2002

cheongthong said:

here master cylinder kits

rtc5834- Master cylinder - repair kit (Master cylinder - repair kit) - - Land Rover Range Rover 2 (P38) 1994->2002

Click to expand...

That is NOT a repair kit for the ABS modulator master cylinder. As can be seen from the illustration.

Piston looks different to the ones I've seen with the broken plastic washer at the bottom. Off the Range Rover classic, perhaps? Maybe the seals etc. are the same? Bit of a risk at £60 though.

Grrrrrr said:

Piston looks different to the ones I've seen with the broken plastic washer at the bottom. Off the Range Rover classic, perhaps? Maybe the seals etc. are the same? Bit of a risk at £60 though.

Click to expand...

That is for the NON ABS vacuum assisted master cylinder. Go here http://lrparts.ru/engl/ select P38 and put RTC5834 in search

That's a useful site - when you find the In English button!

Just won an old one off a well known auction site. Will strip it down and see how it works when it arrives. If I can find an RTC5834 we'll be winning!