• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Vacume gauge reading on servo line

Share this page

J

Jerry

Darth Vader
Gold
Country flag
Offline
I am about to send off my brake servo for repair but tested the vacume at the servo line. The reading was 11-14 at 1500 rpm. Is this normal and would it operate a functional servo?

Jerry
BJ8
22A servo

PS non calibrated, cheapo, vacume gauge
 
Yes that is about it for the Healey. My tests show the stock boodter will operate with as little as 3. However, the test you performed does not exonerate a booster failure. If it fails to work send in for a repair.
 
I'd check vacuum at the manifold for a reference.Myself, I'd like to see 16-18 inches. Of course timing & cam specs can make a difference. I can't remember if there's a check valve or not, it would be easy to install one, come to think of it there may be a metal one in line by the firewall.I'll look in workshop manual tomorrow. cheers Genos2
 
The unit is all boxed up for UPS to go for repair. I took the cover off the vacume chamber and it has new parts inside. So someone did a bad rebuild. I must say once the fender is on, that unit is much harder to remove.
I also forgot to ask. I don't have the one way valve in the vacume line. Does Power Brake Exchange sell them?

Now back to adjusting the carburators! Idle is still too high.

Thanks for your help.

Jerry
BJ8
 
Well the one way valve on a stock booster is the first fitting at the top that the Vacuum line attaches to. Should it be missing a valve can be purchased at most auto stores and installed in the Vac line, However a missing valve should be felt on the brake pedal as a pulsation. and there would be no braking after the engine is shut off.
 
As Keoke says, the one way valve is screwed into the ali housing and the hose attaches to the union end, its shown in this view as the union sitting in the piston.

https://www.austin-healey3000.com/apps/photos/photo?photoid=5130998

Note that on some Girling mk2a servos (fitted to other cars)that this union was a straight thru peice (not a NRV), to check unscrew it and blow thru it to see if it only lets air one way, otherwise you can buy even the original item or one that fits in between the hose.

ps you can also see the union/ one way valve in this page (servo installed), without the hose attached to it:

https://www.austin-healey3000.com/brakes.htm

cheers Andy
 
Ok, I have a one way valve on the servo, so I don't need that. I wondered if the grafite lubrication that was used in the container was too thick to allow movement. It felt more like a very thick grease. Either way, the Power Brake people should be able to fix it.

Jerry
 
It probably was grease. The rebuild kits these days come with that. If you DIY and want dry film, you need to purchase that separate.
 
Back
Top