Brake Servo failure, Marina based Roadster

[wolf_rueffel]

Hello,


unfortunately i have a problem with the servo brake on my Marina based Roadster.
No pressure builds up. It seems like the servo is leaking
The master cylinder is fine and everything is made new.
As soon as I disconnect the vacuum hose, I can brake. And the engine runs smoother ... :-(

You can also hear a whistle when I press the pedal and the pedal falls forward ... Pffft ..

Is it possible to repair anything on the servo at all? Or does it have to be new?
I saw that one screw from the servo is covered by the chassis, I hope I don't have to remove the entire unit:
Clutch pedal, Gas pedal, and brake pedal?

Do you have a tip for me?
And maybe also a tip for a servo replacement, if necassary ?

I thank you for your help

Regards
André

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[wolf_rueffel]

Re: Brake Servo failure, Marina based Roadster

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[martinclan56]

Re: Brake Servo failure, Marina based Roadster

There are companies that can repair servos - however it can be expensive. I am rebuilding a Marlin at the moment and have used a TR6 servo which fits and are available new. My car is far from being completed so can't tell you how well it works!
Cheers Robin
PS some pictures in my build thread.

[Ye Ol Ripper]

Re: Brake Servo failure, Marina based Roadster

Hi Andre

From your photos it's not clear how you managed to run the car to establish this problem, as there is no cylinder head fitted to the car?

1) In the first instance , the rubber where the vacuum fitting fits into the servo doesn't look great, are you sure that it doesn't have a split in it ?
2) Was the rubber hose going from the servo to the inlet manifold and their 2 clamps tight and in good condition?

3) I would also check the underside of the servo from beneath the car looking upwards , as they do corrode on the bottom and there is a chance it's rusted through.

[wolf_rueffel]

Re: Brake Servo failure, Marina based Roadster

Hello Robin,

looks like mine...
f you haven't installed it yet, you can give me the dimensions of the distance to each other
for the fastening screws. Also for the brake cylinder fastening Sc. there is an old Lockheed installed on mine...
Thats would be helpfull,
And do you have a spare part number?


Thanks for help !

André

[wolf_rueffel]

Re: Brake Servo failure, Marina based Roadster

Hi Does the engine run better with the lid on? Then I want to try it :-)

I'm not sure if the white connection nipple is ok ... There is probably a replacement ...
The vacuum hose is OK, If I try to pull vacuum with my mouth, it doesn't stay, no chance ... :-(

It is definitely not rusted, Dave Cunnington revised the Marlin some time ago, there is also a report here ...
Therefore the pictures are also without Cylinder head ...

[Ye Ol Ripper]

Re: Brake Servo failure, Marina based Roadster

Hi Andre
Thanks for the clarification ,I now recall your car and also your you tube footage when you first got it .

With the engine running and servo hose attached the easiest way to determine where an air leak is as follows:

Using Carb cleaner or WD40 spray using the straw around the servo fittings and if its sucking in air at the place you are spraying, the engine note/speed will change.

If the fittings seem fine then repeat around the servo to try and locate a perforated hole.

I also recommend removing the white elbow fitting, remove the rubber grommet , sand off the corrosion from the servo where the grommet contacts . The white elbow fitting should be a very tight fit when pushed into the grommet to make an air tight seal.

Are there any cracks in the White Elbow?

Both the elbow and rubber seal were probably used on other British cars

Possibly MGB and Triumph Dolomite's used the same servo seal and elbow.

[wolf_rueffel]

Re: Brake Servo failure, Marina based Roadster

Hi Andre
Thanks for the clarification ,I now recall your car and also your you tube footage when you first got it .

With the engine running and servo hose attached the easiest way to determine where an air leak is as follows:

Using Carb cleaner or WD40 spray using the straw around the servo fittings and if its sucking in air at the place you are spraying, the engine note/speed will change.

If the fittings seem fine then repeat around the servo to try and locate a perforated hole.

I also recommend removing the white elbow fitting, remove the rubber grommet , sand off the corrosion from the servo where the grommet contacts . The white elbow fitting should be a very tight fit when pushed into the grommet to make an air tight seal.

Are there any cracks in the White Elbow?

Both the elbow and rubber seal were probably used on other British cars

Possibly MGB and Triumph Dolomite's used the same servo seal and elbow.

Thank you for the great tips. That's exactly how I'll do it ..
And I will report.
The "White Elbow" doesn't look very trustworthy, maybe that's my problem?
I have a start pilot, so I will search for the hole against ...

André

[stevejgreen]

Re: Brake Servo failure, Marina based Roadster

The white elbow is a non return valve. Part number RTC812P available from Rimmer Brothers


edit, corrected part number

[wolf_rueffel]

Re: Brake Servo failure, Marina based Roadster

Hello !

Yesterday I tried your tips ...
Unfortunately, it's not the "elbow" valve.
It works fine and is tight. Everything around the brake servo is also sealed.
The "PFFFT" sound comes from inside :-( So the brake servo has to be removed after all :-(

Probably the diaphragm is defective !? Then it will be a little more work ...

Maybe Robin (Martinclan56) can give me the part number of his brake booster?
This would be helpful

Thank at all!

André

[dcunn]

Re: Brake Servo failure, Marina based Roadster

You could check ebay.uk and ebay.de to look for servo repair kits ??????

Just a thought

Good Luck

DC

[martinclan56]

Re: Brake Servo failure, Marina based Roadster

Hello !

Yesterday I tried your tips ...
Unfortunately, it's not the "elbow" valve.
It works fine and is tight. Everything around the brake servo is also sealed.
The "PFFFT" sound comes from inside :-( So the brake servo has to be removed after all :-(

Probably the diaphragm is defective !? Then it will be a little more work ...

Maybe Robin (Martinclan56) can give me the part number of his brake booster?
This would be helpful

Thank at all!

André

Away atm. Will try to find it when I return.

Cheers Robin

[HairyDave]

Re: Brake Servo failure, Marina based Roadster

From my own experience with a leaking hose, the engine is running lean. With a good hose and servo, the brakes were ferocious. Now the servo is not working and the manifold connection is blanked, the brakes need a reasonable push but they are ok.

[wolf_rueffel]

Re: Brake Servo failure, Marina based Roadster

You could check ebay.uk and ebay.de to look for servo repair kits ??????

Just a thought

Good Luck

DC

Hi Dave

Yes, I've already done that. I would like to remove the brake servo first
to see what exactly is defective ...
I'm not sure if only the two O rings and the dust cap are the problem.
The repair kits all look the same, but I'll see if it's the right one,
when I've removed the brake servo. I hope to get to it this week ..

Thank you for your great support to everyone

André

[martinclan56]

Re: Brake Servo failure, Marina based Roadster

I checked my (new) brake servo and the box just says for a Triumph TR6. It fits the pedal box OK except I had to make a thin spacer so that the push rod fitted the pedal OK. On the other side of the servo - where the master cylinder fits - the pushrod is adjustable so it fitted my chosen master cylinder fine.
Cheers, Robin