[SS-Traveller]

Originally Posted by Sutripta

Brake linings might be oversize. Drum might be out of specs. But don't true a new drum, ask for a replacement. In the meantime measure everything.

I agree. Brake shoes are probably non-standard. Standard shoes HAVE to fit in standard drum - no two ways about it. I wouldn't face a brand new drum, but I suppose the job's been done already?

Originally Posted by Sutripta

This normally means either a master cylinder fault, or that one of the circuits is not working, either because it is leaking, has lots of air, or is very badly adjusted.
If the pads are forced apart even slightly, it will displace a lot of fluid. (resulting in the overflow) and will need a lot of pedal travel (or pumping) to recover that lost ground. So please check for warped disks, bad wheel bearings.

IIRC the MC is comparatively new on HVK's car. One of the circuits not working is a good likelihood. Maybe a pipe acting like a one-way valve? (remember having a major issue with this a long time ago)
@HVK: When were the reinforced flexible brake pipes changed last?

[hvkumar]

Originally Posted by Sutripta

Hi,
When you had first described your symptoms, I thought culprit is the servo if the other simpler stuff checks out OK. Still think so.

However

This normally means either a master cylinder fault, or that one of the circuits is not working, either because it is leaking, has lots of air, or is very badly adjusted.

If you tie this in with overflowing of the resrvoir, to my mind it seems that something is forcing your disk pads apart. Pads normally always just touch the disk. Which is why no adjustment is necessary. If the pads are forced apart even slightly, it will displace a lot of fluid. (resulting in the overflow) and will need a lot of pedal travel (or pumping) to recover that lost ground. So please check for warped disks, bad wheel bearings. What is the brake pedal feel like if the car is stationary?

I must add that I am unable to account for the part marked out in bold.

Regards
Sutripta

I changed brake oils.
No leaks anywhere in the system. Brakes bled 3 times +. No leaks in feed pipes.
Brake booster (also a function of the proper functioning of the master cylinder) seems to be working OK in the engine on-off validation tests that I explained above.
Wheel bearings found OK, greased them 2 days ago.
Brake caliper rubbers looked fatigues, changed them.
The forced apart situation - could that be due to some problem with the pistons in the brake caliper?
The air leakage sounds appropriate - which is what I started out with - but where?
Now I have a brake drum which has a wavy surface.

[hvkumar]

I drove back home 41 kms with hardly any brakes, without a handbrake and only the engine braking and gear changing, with the idea that I will stall the vehicle somehow in an emergency. This was in peak hour traffic in Bombay. It is just one of those lucky things that I escaped without mishap.

I have now grounded the Scorpio, awaiting solutions.

My investigations today revealed the following:

- ASC had not put the crde brake cylinder by mistake, they put the Bolero's! Which is worse. that is the reason why the brake drum wore itself out.

- The brake pads were totally worn out, indicating that they were jammed or over-barked. I normally get a life of 30K kms, this time they were totally gone in under 20K

- The brakes shoes were totally gone, especially the LHS one where the wrong cylinder was used.

- the brake drum did not fit yesterday because the brake shoes that I replaced are not the ones for my Scorpio. And the brake shoes that fit my Scorpio are not available in the market. So if the brake drum are the correct one, the brake shoes don;t fit.

- there are no brake drums for my car available in the market. I am looking at accident repair/ discarded brake drums now. Facing them - maybe that will help them fit.

It is a nightmare. A nightmare which every Scorpio owner is going to face the older his car is because of the successive versions and design changes that M&M keeps making all the time, disregarding a design philosophy that demands interchangeability of old design and new design parts. Does M&M really expect its customers to ground their cars and wait indefinitely for parts? I have not forgotten how I had to wait for over 1 month for a simple wheel nut not so long ago!!!!

[hvkumar]

Originally Posted by SS-Traveller

@HVK: When were the reinforced flexible brake pipes changed last?

You mean the pipes feeding oil to the wheels?
I have changed both, one as little as under 3 months ago and the earlier one in mid-2009. They look good and don't have any leaks or abrasions.

[SS-Traveller]

Originally Posted by hvkumar

- ASC had not put the crde brake cylinder by mistake, they put the Bolero's! Which is worse. that is the reason why the brake drum wore itself out.

WOW!

...the brake drum did not fit yesterday because the brake shoes that I replaced are not the ones for my Scorpio. And the brake shoes that fit my Scorpio are not available in the market. So if the brake drum are the correct one, the brake shoes don;t fit.

Right - as I said, standard shoes HAVE to fit in standard drum - no two ways about it.

...there are no brake drums for my car available in the market. I am looking at accident repair/ discarded brake drums now. Facing them - maybe that will help them fit.

Will the newer Scorpio's complete rear brake system fit the older version? Drums, w/cyl, shoes, backing plate... the whole works. Your opinion please, Spike.

Originally Posted by hvkumar

You mean the pipes feeding oil to the wheels?
I have changed both, one as little as under 3 months ago and the earlier one in mid-2009. They look good and don't have any leaks or abrasions.

Yes. There should be 4 in total (I hope I'm correct, Spike ). Check the insides of each one for softened / melting rubber (did your brake oil look normal the last time you changed it, or was it cloudy?). Also the booster-to-EGR pipe, as we discussed earlier. Did your Scorpio model come with an LSPV (Spike please confirm)? (malfunctioning or not? setting of the control spring needs to be measured and reset if required - 92mm IIRC - is that correct, Spike?).

The brakes shoes were totally gone, especially the LHS one where the wrong cylinder was used.

Can also happen with wrongly set LSPV...

[hvkumar]

Originally Posted by SS-Traveller

Yes. There should be 4 in total (I hope I'm correct, Spike ). Check the insides of each one for softened / melting rubber (did your brake oil look normal the last time you changed it, or was it cloudy?). Also the booster-to-EGR pipe, as we discussed earlier. Did your Scorpio model come with an LSPV (Spike please confirm)? (malfunctioning or not? setting of the control spring needs to be measured and reset if required - 92mm IIRC - is that correct, Spike?).

I have changed both the front feed pipes and I think the rear ones too (but not sure of that). In fact, that was the first thing I changed when I started developing the braking problem. A small hole was discovered in one of the feed pipes but very little oil leak, looks like air must have been entering the brake system that way.

Brake oil looked normal. Since this problem has been going on for some time now, the brake system has been topped up after every successive bleeding session.

What is LSPV?
EGR rubber pipe is still not changed, it has got submerged under the weight of the brake drum discoveries. In any case, the pipe is not available with ASC.

[SS-Traveller]

Originally Posted by hvkumar

What is LSPV?

Load-sensing proportioning valve. Looks like this on the newer Scorpios - no idea if yours has it...


Try going through this too... LSPV - What is it? and LSPV Adjustment with Pictures (just for an idea, not applicable to how it's done on the Scorpio).

[SPIKE ARRESTOR]

Originally Posted by Sutripta

What do you think of the rest of my reasoning?

Originally Posted by Sutripta

When you had first described your symptoms, I thought culprit is the servo if the other simpler stuff checks out OK.

Even I thought so, it is the "erratic" behavior which I am unable to comprehend. Whats wrong in servo-> Compensation port?

This normally means either a master cylinder fault, or that one of the circuits is not working, either because it is leaking, has lots of air, or is very badly adjusted.

OK, so you were referring to rear brakes.

If you tie this in with overflowing of the resrvoir, to my mind it seems that something is forcing your disk pads apart.

OK, but did it happen in this case?

Pads normally always just touch the disk. Which is why no adjustment is necessary.

OK.

If the pads are forced apart even slightly, it will displace a lot of fluid. (resulting in the overflow) and will need a lot of pedal travel (or pumping) to recover that lost ground.

OK.

I must add that I am unable to account for the part marked out in bold.

Same here.

Originally Posted by SS-Traveller

@HVK: When were the reinforced flexible brake pipes changed last?

Those are armored flexible pipes, "reinforced" has a different connotation.

Originally Posted by SS-Traveller

Yes. There should be 4 in total (I hope I'm correct, Spike ).

3-4 it depends. Usually 2 for the front wheels, 1 for rear (LSPV to Brake Tee joint).

Did your Scorpio model come with an LSPV (Spike please confirm)? (malfunctioning or not? setting of the control spring needs to be measured and reset if required - 92mm IIRC - is that correct, Spike?).

Yes, very close Dada. It is 91.5 mm precisely.

@HVK does your Scorpio have a single pot or double pot caliper? Also which make? KBX or Brakes India Ltd.?

Originally Posted by SS-Traveller

Load-sensing proportioning valve. Looks like this on the newer Scorpios - no idea if yours has it...

Dada pictures of LSPV from where??

Spike

PS- A picture paints a thousand words.

[Sutripta]

Originally Posted by SPIKE ARRESTOR

OK, but did it happen in this case?

Don't know. Not being able to see the vehicle physically, we are playing armchair detectives. Any other theory which ties in all (or most) observations?

Regards
Sutripta

[SPIKE ARRESTOR]

^^ Yes, there is one more culprit which usually goes unnoticed. The Brake switch mounted on the suspended pedals, improper setting of this can also result in some of these symptoms.

Spike

[SS-Traveller]

Originally Posted by SPIKE ARRESTOR

Those are armored flexible pipes, "reinforced" has a different connotation.

Sorry - you're right - armoured, not reinforced. Absent-mindedness!

Dada pictures of LSPV from where??

Sshhhh....

Originally Posted by SPIKE ARRESTOR

...Brake switch mounted on the suspended pedals, improper setting...

Given that some nutcase fitted a Bolero w/cyl in a Scorpio, even this is worth checking out!

Spike, you're located the closest to HVK. A weekend visit to Thane seems imperative for you now!

[Sutripta]

Originally Posted by SPIKE ARRESTOR

^^ Yes, there is one more culprit which usually goes unnoticed. The Brake switch mounted on the suspended pedals, improper setting of this can also result in some of these symptoms.

Spike

Hi,
You mean lack of freeplay/ clearance in the pushrod? Ultimately causes the brakes to bind/ lock up. Anything else?

Regards
Sutripta

[SPIKE ARRESTOR]

^^ Yes, it prevents the brake pedal from returning properly, resulting in erratic servo type symptoms. The brake remains partially applied resulting in binding / drag.

Spike

[Sutripta]

Originally Posted by SPIKE ARRESTOR

^^ Yes, it prevents the brake pedal from returning properly, resulting in erratic servo type symptoms. The brake remains partially applied resulting in binding / drag.

Spike

Hi,
How much misadjustment are we talking about here? ~ 5mm?

Since the ECU reads brake application, is there any way of physically removing and temporarily bypassing the switch?

Regards
Sutripta

[kaushik_s]

Originally Posted by SPIKE ARRESTOR

OK, I presume after 4 chirps you entered the 4th digit using the valet switch. If yes, then did you :-

Turn vehicles key to Ignition 'ON' & keep it 'ON' for 10 secs? One long beep confirms the completion of secret code password programming.

Do you need contact details of the Nippon guy at Bangalore? Let me know.

Spike

I tried to change the code today and what happened this time is that I heard a long chirp even before I could do the ON procedure. I tried again and it's same, after the 4th digit I heard the same beep. And if I do the ON procedure I don't hear anything. I think I'll give the Nippon guys a call and let them check.