MK Brake Master Cylinder--help--

[Crankshaft]

G'day all

I am fairly sure the Brake Master Cylinder (BMC) on my 3/85 MK patrol is sick.

It seems one circuit is inoperative. Pulls to the left under brakes with no sign of fluid on the RH brake. or any of the others.

Pedal is low and while it pumps up, no improvement occurs.

It is a 2.8l Petrol LPG with only less than 150 k on it so I am not after a patch up job and so am looking for a new BMC.

Now the difficulties
No references in the books for a BMC for an MK at the local auto1
I can get one on ebay for an MQ that looks identical but the add says 25mm piston
The ebay shop man says he has 4 references for the MK ?????
When I look at the Service manual it lists a 22.? dia piston for the MK
Otherwise they look identical



Will it work?
Is it a straight swap?
Are there any other subtle differences?
A bigger piston will mean a higher pedal pressure by about 30% -- yuck

Does anybody have any reference material or details



Cranky

[GQ TANK]

Before you start swapping master cylinders - I would bled the brakes and see if you are getting flui - dont forget the equliser.

I would also chek the brakes and adjust the rear drums
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[Crankshaft]

Thanks for your suggestions GQ tank

The system has been bled and I found no air
BUT
by skidding in the gravel I have found that neither front brake is working and that the reason it was pulling to one side was a bit more dust in one of the rear brakes.

None of the wheel cylinders is leaking.

So My original question still stands .

Does anybody know if it is the same part for the MK and GQ ??

Cranky

[iansmqshotyy]

why not just pull it down and kit it? should be no more then $30 ish and a few hours work odds are its just a bypassing seal

[MQ MAD]

Thanks for your suggestions GQ tank

The system has been bled and I found no air
BUT
by skidding in the gravel I have found that neither front brake is working and that the reason it was pulling to one side was a bit more dust in one of the rear brakes.

None of the wheel cylinders is leaking.

So My original question still stands .

Does anybody know if it is the same part for the MK and GQ ??

Cranky
Sounds like its a wild goose chase ....
Give the system a proper check over, clean , maybe full system flush, bleed correctly and adjust then make a decision
GQ master cylinders have a bigger bore from memory,have been fitted onto MKs but cant remember what the issues,problems or dramas were
MK master cylinder will have a bore size ,or some ID numbers on the outside of the master cylinder ,use them when re ordering,makes it easier

[droppa]

Before you start swapping master cylinders - I would bled the brakes and see if you are getting flui - dont forget the equliser.

I would also chek the brakes and adjust the rear drums
\

what/where is this on the MQ patrol......having some brake problems myself.....