Peugeot Expert Van 1.9d 2001 Brakes - master cylinder woes??

Question

Hi, after not using the van for around 3 months and wishing to sell it, I went to drive it and found the brake pedal sinking to the floor. Thought they needed bleeding but the first bleed nipple I tried (relatively gently, using plusgas and heat etc) sheared off. Got a mechanic to change the rear wheel cylinders and bleed system. Tried it again, same problem. Thought 'master cylinder', as did he. Got hold of another master from a breakers which he fitted, and I helped him thoroughly bleed the system again. Guess what, still pretty much the same - brakes work fine, but steady pressure on the pedal and it sinks nearly to the floor. No leaks that I can see,front pads seem to move, work, etc when they should. Got in touch with the breakers who said they were familiar with the vehicle it came off of, and as far as they are aware the master they sent worked fine.

The mechanic says, "brake efficiency ok, should get through mot", but I'm not sure I want to try selling a van with dodgy brakes. He had to replace a brake line as one of the connection pipe nuts rounded off as he tried to loosen it, and all in all, with other work on my other vehicle I've paid him a fair bit to sort various things out. The van had a load of brake fluid left over the parts of the van under the bonnet under the master reservoir, as well as all over it, and there are some yellowish marks on the paint where i think he has brushed past it and got brake fluid on it. I would have at least tidied things up a bit if it had been me, put newspaper under it etc to absorb spills.

I've arranged for him to take it to the Mot this thurs, but I'm thinking to cut my losses, and rather than pay him, find someone else, maybe a different mechanic I've used before to sort the problem, then arrange short term insurance and get the mot myself.

Any suggestions appreciated.

John Williamson · Accepted Answer

Speaking as a cynic, they would, wouldn't they? I'll bet the guy that told you that hadn't driven the vehicle.

Might be the servo, if fitted. A leak on that won't necessarily show from the outside.

Apart from that, I'd *never* use second hand brake parts, no matter how good the vehicle they came off was supposed to be.

Mrcheerful · Answer

buy a new master cylinder. Even if the cylinder seemed OK on the original vehicle, when it is used through its full travel as when bleeding the brakes it is easy for the seals to go past a damaged or rusty area and tear the seals to pieces, I have seen this several times, it can also occur after fitting new brake parts without bleeding, just the longer travel needed to push the pistons out can be enough. After fitting new brake parts I avoid pushing the pedal excessively, just little dabs till the pressure comes up.

yeeoh33 · Answer

Thanks for the advice. The story gets a little more murky. It failed the mot on the pedal sinking under sustained pressure - just as I suspected it would and in spite of the advice of the mechanic I used who believed it would get through. I spoke to the breakers, who said that someone who works next door to them had a fault with his van on the brakes, which after fitting a replacement master cylinder, turned out to be the wheel cylinders. I pointed out to them that this would not preclude the master from being faulty, and with regard to the suggestions above, it now not being serviceable. I used them because apart from being cheap, they offered a guarantee. The mechanic now believes it is the servo that's at fault, but I don't believe that's the case. It just happened that he also met a mate of his at the mot shop, who offered to buy the van from me (he deals in vehicles); I do want to sell, but it's a decent vehicle and I'm not that stupid as to let it go for a song.

Have now ordered a new master cylinder, and given the story so far, and that I can't find another decent sounding mechanic, will have a go at doing it myself. All the unions and bleed screws have already been loosened once, so am hoping it will be relatively straightforward. If it is the master cylinder at fault, the lesson is, don't buy them used!

Mrcheerful · Answer

it is very easy to eliminate cylinders/calipers leaking (fluid will be visible!) all you do is clamp all 3 or 4 flexibles and try the pedal, if it is now much better then you know there is either a cylinder fault or air in a cylinder

Mr Pounder · Answer

Narr, the OP is a skint merchant.

Duncan Wood · Answer

Could be worse, he could be clueless.

Rob · Answer

You do know that the pedal will sink on a diesel because it does not take the vacuum off the inlet manifold! (not to the floor but will sink somewhat.) it uses a pump.

Visual the back of the master cylinder to see if its leaking from the rear seal. (it still could be the internal seals bypassing) and check and see if any wheel cylinders are leaking from under the car usual to run down the brake backing plates (wheel usually on top)

Another test is using light foot pressure on the pedal will allow it to sink if the rubbers are being bypassed. heavy pressure will most likely force the seals to spread and retain pedal pressure.

Peugeot Expert Van 1.9d 2001 Brakes - master cylinder woes??

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