Singr07 · Monday at 15:03

Hi Folks
Need some help on the 300tdi conversion brakes. I have noticed some weird thing about brakes, may be when the weather is bit warm. When I press the brake peddle for little bit longer then peddle slowly goes all the way down. When I apply the double brakes then brake peddle gets hard again. Is it just me or that’s how ot is supposed to be? Please help

lynall · Monday at 15:20

Discs all round or drums on the rear?

300bhp/ton · Monday at 17:34

Could be a vacuum leak. Servos can get hairline cracks in them. So no not normal.

Could be fluid related if contaminated with water or air or a small fluid leak. But it would probably feel slightly different.

Singr07 · Monday at 17:37

lynall said:
Discs all round or drums on the rear?

Hi it has discs all around

Singr07 · Monday at 17:40

300bhp/ton said:
Could be a vacuum leak. Servos can get hairline cracks in them. So no not normal.

Could be fluid related if contaminated with water or air or a small fluid leak. But it would probably feel slightly different.

Fluid has been renewed recently, I will try to check the Servo and Vaccum leak. But most of the time brakes are solid, it’s only happening on long break

lynall · Monday at 18:44

Singr07 said:
Hi it has discs all around

New or rebuilt calipers?

300bhp/ton · Monday at 21:19

Singr07 said:
Fluid has been renewed recently, I will try to check the Servo and Vaccum leak. But most of the time brakes are solid, it’s only happening on long break

Last sentence.

Wimblowdriver · Monday at 21:25

Seals in the master cylinder might have failed, letting brake fluid flow back to the reservoir.

Singr07 · Monday at 21:49

I can hear some Air leaking sound under the bonnet, but my hearing is not so good due to an ear drum surgery.

I have just recalled vacuum pump was replaced few years ago by a mechanic and I have only driven around 2k miles since then ( within last 4 year ).
When that mechanic replaced the vaccum pump he used the TRV sort of sealant as he couldn’t find the gasket. And I have watched some videos on YouTube and noticed people are using 2 gaskets with a sealant on the Engine block.

I wonder it may be a leaking from there. Is there any way to test the air leak on the Vacc pump on the engine, may be to spray some liquid on it to see the any air bubbles. Would that be a good idea? I would really appreciate your precious advice. Thanks

Singr07 · Monday at 21:50

Singr07 said:
I can hear some Air leaking sound under the bonnet, but my hearing is not so good due to an ear drum surgery.

I have just recalled vacuum pump was replaced few years ago by a mechanic and I have only driven around 2k miles since then ( within last 4 year ).
When that mechanic replaced the vaccum pump he used the TRV sort of sealant as he couldn’t find the gasket. And I have watched some videos on YouTube and noticed people are using 2 gaskets with a sealant on the Engine block.

I wonder it may be a leaking from there. Is there any way to test the air leak on the Vacc pump on the engine, may be to spray some liquid on it to see the any air bubbles. Would that be a good idea? I would really appreciate your precious advice. Thanks

dag019 · Monday at 22:53

Wimblowdriver said:
Seals in the master cylinder might have failed, letting brake fluid flow back to the reservoir.

This one is what it was when I had similar symptoms.

tottot · Tuesday at 08:17

A basic test for the vacuum pump Is remove pipe from the servo and with engine running put your thumb over the end, pipe sticks on vac is good.

Singr07 · Tuesday at 18:45

tottot said:
A basic test for the vacuum pump Is remove pipe from the servo and with engine running put your thumb over the end, pipe sticks on vac is good.

Hi I did remove the vacuum hose then stated the engine and vacuum is sucking and seems to be working.
I have took the picture of the Vacuum pump and there is no sign of any leaks on the engine block.
I have removed the Master cylinder and there is no cracks on the front of Servo (picture attached)
But when I have drained the master cylinder then it has the sludge at the bottom of Brake fluid reservoir. I did change the Brake fluid not long ago and I was able to bleed the brake hoses until I seen no air bubbles and clear brake oil.
Shall I just replace new the Master Cylinder on the safe side?

Wimblowdriver · Tuesday at 19:15

Singr07 said:
Shall I just replace new the Master Cylinder on the safe side?

I think that's where the problem is. I'd replace if it was mine.

tottot · Tuesday at 21:07

Crud in the reservoir is usually very small bits of seals from the master. The pedal slowly going down is a sign fluid is passing around inside the cylinder.

Singr07 · Tuesday at 21:29

Thanks for your advice I am going to fit a new Master cylinder.
Do you know if anyone sells old type brake Servo booster for my Defender 90. LOF clutches don’t have for old type (only 2 brake lines out pipes).

tottot · Tuesday at 22:14

I had a new old type 80 servo for mine a while back from "rstlandrovers" Mines a 1990 model What year is yours?

Singr07 · Tuesday at 23:29

Hi it is 1989 with 300tdi conversion

Singr07 · Wednesday at 10:03

Singr07 · Wednesday at 10:04

Hi does anyone know the seal part number for this Brake master cylinder please?

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