General Brake Pressure Regulator: MOT Failure

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General Brake Pressure Regulator: MOT Failure

chr1s

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The Ulysse failed its MOT yesterday for "brake load sensing valve linkage seized".
(Also a deep cut in a tyre and two rear lights, which were working when I checked after driving home - must be intermittent contacts on the hatch).

Has anyone tried freeing and greasing a seized Mk1 Ulysse brake load mechanism? I don't fancy buying a new one (£188 on ePer) if I can avoid it.

Also, if I remove and then refit the original, do I need to readjust it with all the pallava of making shims, loading the car, and crawling underneath? Is it sufficient to keep the set-up as close as possible to how it is now, and not bother re-measuring?
 
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chr1s

chr1s

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I can open and close the valve by hand, without much effort, but the small spring doesn't snap the valve closed after I open it.
Does the valve have to move freely enough to automatically snap closed?
Any ideas how I can loosen it up, other than spraying penetrating oil and repeatedly working it open and closed for a while?
 

Pat H

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You could always look at a stronger return spring.
The pull against the spring is the car lifting at the back when braking so the extra hold back of the spring shouldn't make any difference.
 
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chr1s

chr1s

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Thanks for the advice.
Another dose of penetrating oil today seems to have done the trick.
I'll find out on Tuesday when it goes in for a cam belt change and MOT re-test.
 
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chr1s

chr1s

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MOT (y)
Cam belt (y)
Credit card (n)

I was so so lucky with the cam belt. It had three splits from 5mm ~ 8mm, just waiting to break! :eek: Sorted now though.

Make sure your cam belt is changed within the recommended intervals !
 

Pat H

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Make sure you keep an eye on that brake valve. I often find that if things have seized up and been freed with penetrating oil they are prone to siez again. It's an important safety feature as it lowers the rear braking force as the back of the car rises up under heavy breaking. If it siezes up you could lose the back end under a heavy emergency stop.
I'd be temped to give it a sqirt of some nice oil and maybe slap a bit of grease round it to stop the water getting in.
 

Paul L

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Pat H said:
Make sure you keep an eye on that brake valve. I often find that if things have seized up and been freed with penetrating oil they are prone to siez again. It's an important safety feature as it lowers the rear braking force as the back of the car rises up under heavy breaking. If it siezes up you could lose the back end under a heavy emergency stop.
I'd be temped to give it a sqirt of some nice oil and maybe slap a bit of grease round it to stop the water getting in.

Just a question but is this as the car doesn't have ABS?

Paul
 
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chr1s

chr1s

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No, the car has ABS. Quote from the Fiat manual: "The load proportioning valve operates independently of the intervention of the A.B.S. and automatically limits the braking pressure according to the load on the rear axle".

See page 52, attached (also the diagrams on pages 45, 51, 53 and page 77 for '97 to '99 models).
The original pdf is way too big to upload!

However, from 2000 the Ulysse has Electronically Controlled Brake Force Distribution (EBD) which seems to be a more advanced form of ABS, and "the introduction of this function makes the use of the conventional mechanical load proportioning valve superfluous and it has been removed from the rear hydraulic brake circuit" (page 95).

So it looks like the earlier models of Ulysse have a simpler form of ABS system which still requires the load proportioning valve. I can't exactly say why, though, without a more detailed look at the ABS system operation.
 

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Pat H

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Yes very wierd you would have thought that ABS would be far better than any mechanical value. I suspect the ABS function on the rear tyres is basic (if there at all) as it's the front that does most of the work under heavy breaking.
 

housedadtrainz

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The Ulysse failed its MOT yesterday for "brake load sensing valve linkage seized".
(Also a deep cut in a tyre and two rear lights, which were working when I checked after driving home - must be intermittent contacts on the hatch).

Has anyone tried freeing and greasing a seized Mk1 Ulysse brake load mechanism? I don't fancy buying a new one (£188 on ePer) if I can avoid it.

Also, if I remove and then refit the original, do I need to readjust it with all the pallava of making shims, loading the car, and crawling underneath? Is it sufficient to keep the set-up as close as possible to how it is now, and not bother re-measuring?

hi.
when my peugeot failed on that i was told as long as the linkage moved it would pass. i was told on most vehicles its put on but not used. i freed mine of with some wd and patience. Greased it up and it passed.
hope this helps.
 

ANDY1965

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Jul 6, 2009
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Has anyone tried freeing and greasing a seized Mk1 Ulysse brake load mechanism? I don't fancy buying a new one (£188 on ePer) if I can avoid it.

Hi, I had to get one of these on my old 99 ulysse, only cost me about £55 with delivery and about £40 for fitting, but I know the mechanic who was sorcing one told me he was getting quotes for this part from 115 to 185, got the part from shopforparts, its called a brake compensator
 

cipher

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Jul 16, 2006
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The load compensator valve or load sensing proportioning valve, is a common MoT failure point on many cars.

At the end of the day, it is a service item to grease this, and check its operation at every service.

If it does stick, then as said, a (good) penetrating oil, and operating the mechanism by hand should free it up.

If not, then you will have to replace the valve, source a good one from a breakers if cost is an issue, they aren't too difficult to fit.
 
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