The V8 Owners Forum -

GT40 yada yada yada

Driving it now that a few bits are sorted

Put foot on brakes and when getting slow (10mph) strange noise like a pump running

Now it may be making the noise all the time but this thing is so loud I can't hear it!

It also does not like idling and dies when I put foot on brake pedal.

Putting them together could the booster be leaking and leting the engine get too much air?

Hw do you test them?

cheers
Ian

Required :

* Vacuum gauge
* Plug for vacuum port on the intake manifold
* Friend or significant other to work brake pedal
* Sticky back plastic
* 2 cotton reels and a Fairy Liquid washing up bottle

Method:

Attach the vacuum gauge. Start the engine. Note the value. This is your base reading.

Stop the engine, disconnect the servo vacuum line and plug the port on the manifold. Start the engine, look at the gauge. If this reading is much higher than the base reading, you have a leak in the system, probably in the hoses leading to the servo.

Stop the engine, remove and test the one-way valve (should be able to blow into it one way but not the other). Air should only pass in the direction indicated by the arrow printed on the top of the valve (make sure to reinstall it in the correct direction).

Reconnect the one way valve and vacuum line to the manifold and start the engine. Watch the vacuum gauge as a friend (or significant other) depresses the brake pedal. It should fall as the pedal is depressed and return to the base reading. If it drops slowly, but returns, you have a blocked/partially blocked vacuum hose. If it falls and does not return, you have a hole in the servo diaphragm. A hissing when the pedal is depressed is almost certainly a torn diaphragm.

Throw away the Sticky back plastic, 2 cotton reels and the Fairy Liquid washing up bottle but you still get your Blue Peter badge

do you have a PCV vave fitted.?? do you have the correct hose for the servo, IE Servo hose, Big cams will not readily support a servo due to the inherrent lack of vacuum with these cams

What type of servo is it? If its the remote Lucas type they have a nasty habit of the plastic valve cracking so it leaks.

Dont forget to tape up the Brand name Fairy so the cameras cant see it LOL

Thanks for the suggestions I'll collect the Blue peter stuff asap.

I do not think I have a PSV valve thing in the system

It is the remote lucas things

System is taken off center outlet on plenum into HP hose for the bends then steel pipe to the front T junction to a servo on each system.

It soes sound like I could have a leak so I'll try and run without the servo boosters - the pedal ratios etc were very close but for SVA we decided servo was a good idea. Need to drive to Stoneleigh for the Kit car show this weekend!

If I unplug the vacuum (blank it at the engine) will running the car without the vaccuum on the boosters cause them any damage? (More than may be there already????

cheers
Ian