Brake servo confusion on 110 1989 year (was 19j now 200Tdi)

[Jocklandjohn]

I think my over-30 year old servo needs replacing. But trying to figure out what I've got is confusing me.

Parts manual says it should be a Type 50, 227mm diameter, non-return valve aperture bottom right of centre. (The other servo is Type 80 which is 276mm dia. with non-return valve at top left of centre).

Mine is certainly 227 and *looks* correct except for the non-return valve which is at top left of centre (as would be the case for a Type 80). See picture - is this because its been put on upside down? Will it fit upside down?

Also if I'm replacing it can I do so without having to re-bleed the brakes - will it slip out of the reservoir without leaking - assuming the reservoir seals are intact?

 

[western]

You need a type 50, small diameter wide from front to back, same as my 1989 110CSW 

[Jocklandjohn]

Thanks Ralph, I take it the hose/valve can be either way (top left or bottom right depending on orientation?

[western]

Pretty much, it will only fit 2 ways, IIRC mine is the same as yours, hose/nrv towards the engine. 

[Jocklandjohn]

Thanks, you're a fount of knowledge!

[Northwards]

I pulled my master cylinder off the servo recently and found the O ring between it and the servo was pretty flat and dry.

I got a new one, a bit of Vaseline, and I’d say something as simple as that has made a significant difference to my brakes.

By which I’m suggesting that if you’re planning to change the servo, it might be an idea to get a new O ring ordered up.

I have flexible hoses now, so easing the master cylinder off and away from the servo is dead easy, but before I had those I used to find that there would be just enough room with the solid pipes to lean the master away and remove(replace the servo.

[western]

No O ring on my master cylinder body, the servo is sealed, 

[Northwards]

Sorry, meant to say mine is a 1994 300Tdi, but I admit I assumed they’d all have something like that.

[Jocklandjohn]

22 hours ago, Northwards said:

I pulled my master cylinder off the servo recently and found the O ring between it and the servo was pretty flat and dry.

I got a new one, a bit of Vaseline, and I’d say something as simple as that has made a significant difference to my brakes.

By which I’m suggesting that if you’re planning to change the servo, it might be an idea to get a new O ring ordered up.

I have flexible hoses now, so easing the master cylinder off and away from the servo is dead easy, but before I had those I used to find that there would be just enough room with the solid pipes to lean the master away and remove(replace the servo.

Thanks Donald. Its not been touched for more than 20 years so not certain how easy it will come apart! I seem to recall reading somewhere about "maybe an O ring is supplied, maybe its not" but I have a box of assorted to draw from so hopefully if its needed I'll have one.

I've not forgotten I said I'll swing by on intake matters, have been full-on last few days with Clay Shooting at Moy with Croy Scouts (the Scouts do the traps and the Cubs do litter picking) so been out early to late (Moy was great success again, and Scouts/Cubs had a busy but enjoyable time, apart from the occasional midges horde!)  but will ping you during week.

[Jocklandjohn]

Update: I think I need a grown-ups help!

Eased off the brake master cylinder very carefully and was able to slide off the servo, and replaced it with the new one.  Also replaced the hose from the engine pump.

What I discovered has me puzzled. The underside of the master cylinder has a cut out - see the photo taken using a mirror - there's nothing on the old servo that will match this, its just got a round hole like the new one. The weird cut out goes down the side of the end of the master cylinder (where it goes into the servo) but is also continued into the mating face widening to a fan-shape. Once you orientate yourself in the mirror image its clear to see. The o ring/seal that was on there is in my hand with the depression clearly visible in it caused by the cut out.

 

 

Is this normal? It doesn't look it!

I put it back together as best I can and tried the pedal before starting the engine and it was very firm. I then started the engine and tried again and the pedal sunk a lot before I could feel resistence. I've run it for a few minutes and its still the same, needs more than half the pedal travel before I get any resistence although if I do a couple of pumps of the pedal one after the other it gets really strong resistence in the first 1/4 of the pedal movement as I'd expect from properly operating brakes.

Would I be correct to assume that the weird cut-out/shonky seal is the culprit and its lack of a proper seal with the servo is causing a loss of pressure? 

Edited August 11, 2023 by Jocklandjohn

[Jocklandjohn]

Ok further info - discovered this image online - which appears to show that the cut-out is a factory thing thats on the early master cylinders. So now I need to see if there's a special gasket for that. Anyone know a part number - the parts manual (AFAIK) doesn't show one.

 

Its listed as: LAND ROVER SERIES 2 BRAKE MASTER CYLINDER ASSEMBLY LWB/110.PART- NRC8690G

[hurbie]

maybee it's in the rebuilt kit for the servo 18G8951L for the type 50 or AEU2741 fot the type 80

if i don't forget i can have a look this weekend , i have at least one bulkhead with the older mastercylinder , to see if it has some sort off seal in between.

 

[Jocklandjohn]

19 minutes ago, hurbie said:

maybee it's in the rebuilt kit for the servo 18G8951L for the type 50 or AEU2741 fot the type 80

if i don't forget i can have a look this weekend , i have at least one bulkhead with the older mastercylinder , to see if it has some sort off seal in between.

 

Thanks Hurbie -  that would be very helpful!

I managed to obtain a 40mm x 3mm O-ring and tried that but its still not giving me the full pedal resistance so I assume it needs the appropriate seal to go around the groove/cut-out. I dont have any leakages from the master cylinder so I;m hopeful its just the seal thats the problem.

[Jocklandjohn]

I found another picture of the master cylinder I have - this is the thing - weird image but once you get your eye in to what it shows - its the mating face to the servo and its got a vertical groove down the side of the protruding section on its lower side and a fan-shaped cut out on the mating face. I assume thats there for a reason but if thats supposed to actually make an air-tight seal to the servo (?) it must have a really peculiar shaped gasket.

I was under the impression that the master cylinder to servo required an air-tight seal but that looks like some fluid/air pressure relief channel otherwise I cant see the point of having it.

[Jocklandjohn]

I *may* have found the problem.

The new servo does not have a seal in it (and I assume it should have one). This seal is in the old servo I removed - however one is not present in the new servo, which strikes me as odd.

When the rain eases off later I'll try this in and see if it fits/helps.

 

 

 

[hurbie]

maybee the cutout is there to allow brake fluid to exit the master cylinder , in case of a bad seal , and prevent it from entering the servo .

 

[muzaz]

As luck would have it I came across this thread while searching for the part no of the brake master cylinder. Just removed the brake servo and master cylinder off a 1988 nintey.

The master is similar to the one in your photo and the seal (if it's a seal not sealant) is shaped like yours. Here are some pics of mine.

Hope it helps

[hurbie]

just had a look , 1 have two bulkheads (110) with the old mastercylinder 

first one :

swervo:

 

second one :

 

servo: 

 

also had a look in the serie's 3 manual , but no seal there . 

maybe the seal is suplied in the rebuilt kit for the mastercylinder ?

 

Edited August 12, 2023 by hurbie

[hurbie]

doesn't look like it : 

https://www.johnrichardssurplus.co.uk/brake-master-cylinder-kit-aeu3015-girling.html

 

[Jocklandjohn]

Thanks a lot for doing these pictures Hurbie.

7 hours ago, hurbie said:

maybee the cutout is there to allow brake fluid to exit the master cylinder , in case of a bad seal , and prevent it from entering the servo .

 

Thats my conclusion too. Its got to serve some purpose and being at the bottom makes sense for fluid exit.

Now - the excellent pictures I think *may* solve the problem. My master cylinder's end look like yours but both of your servos have a seal in them - most obvious in the second picture down. I have no seal in the new servo, but did have one in the old one I've removed.

My conclusion is that the new servo has not had one installed, or you're expected to supply your own, which seems rather daft as (it may be the case that) it wont work without it! I will report back tomorrow after getting the salvaged seal into the new servo and seeing if it helps....