Is brake fluid in the servo causing a high idle? SOLVED

[Jiminwatford]

For the last few months i have had a brake fluid loss. I often don't visit the car for weeks at a time but the reservoir always needs filling when i do. I had assumed it was coming from a flexi pipe i replaced last year but it isn't

This week after starting the car for the first time in a few months there is a high idle of around 1400 rpm. I've been advised it is likely a vacuum leak. I sprayed carb cleaner around the carbs and heard no change in the engine noise

Someone mentioned the fluid loss and vacuum leak could be linked. So i checked the pipe going from the servo to the inlet manifold and found fluid in there

I will want to know why fluid is getting into the servo but i would first like to know if there is a way to test to see if the fluid / servo issue is causing the high idle (i.e. vacuum leak)

I thought putting my thumb over the pipe going to the intake manifold might do something but it didn't seem to. It does run rough when that pipe is left off the servo though

 

[cobraboy]

White smoke from the exhaust is a sure sign of brake fluid being burned by being sucked into the intake from the servo. This happens when internal seals in the servo fail.
A high idle speed when the throttles are closed and the idle screws are un responsive indicates the engine is getting air from another source ( leak )
You can isolate the servo as a cause by clamping the vacuum hose and seeing if the idle drops.
You may find it is a leak from elsewhere. Try spraying carb cleaner around intake gasket, and carb to intake areas and see if the idle speed changes.
The car will run rough when the servo vacuum hose is disconnected, as you have introduced a massive air leak.

 

[Jiminwatford]

SOLVED

I replaced the servo which was needed anyway. I tried carb cleaner all around and the carbs seemed to be returning off throttle

But this is why the idle was so high: when i put the carb back on at Christmas i must have pulled on the choke cable too much and possibly pushed the choke itself slightly up the cable meaning it was always slightly on

It took a visit to Kelbrook Classics Welcome to Kelbrook Classics (who i highly recommend) to notice the choke wasn't fully releasing and there was a kink in the cable a bit further down where it used to be attached

I think because an orange light comes on when it's time to push the choke in i hadn't looked closely enough at it but of course that works in a different way

So a relief to get fixed and hopefully maybe someone else might find this useful

 

[jp928]

I had a similar experience early in my ownership - fast idle hanging on. When I looked at the cable end at the carb, the end of the cable outer had backed out of the ferrule (thats retained in the carb part with an R clip), and was sitting on the edge of the ferrule. Careful application of super glue seems to have fixed it. Later on I had another cable problem - the cable broke off the end of the knob stem. I ordered a new cable (while I tried to re-attach the cable to the stem - successfully), and learned that the ferrule does NOT come with a new cable.