| Aux Vacuum Pump comes on (brake vacuum) [message #297097] |
Thu, 10 March 2016 15:34  |
George B.
Messages: 213
Registered: February 2012
Karma: 1
|
Senior Member |
|
|
I have a GM aux vacuum pump installed and recently it has started running a few times when I press on the brake pedal. It is usually when I first start up and am backing up or maneuvering around my parking area. Never has done that before. When I am out on the road it does not come one. I checked my vacuum hoses to the master cylinder and the one running to the rear of the engine and hooked up with others at the cruse control. All seemed OK. Brakes seem to work OK while driving around town. Just not sure if the, I suppose, low vacuum at idle causing the pump to run is an indication of something going wrong. Checked brake fluid level and is OK. Any ideas?
George Butts
Las Vegas Nevada
73 "Custom 26' Q" & 76 23' Birchaven
71 Honda 600 Coupe & 01 Tracker Toads
|
|
|
|
| Re: Aux Vacuum Pump comes on (brake vacuum) [message #297116 is a reply to message #297097] |
Thu, 10 March 2016 20:50  |
Gadabout
Messages: 124
Registered: March 2013
Location: Edmonton
Karma: 2
|
Senior Member |
|
|
Hi George ,
I expect when your moving the GMC around the yard, you are on and off the brake pedal contributing to the low vacuum condition that you would not experience under normal driving.
A leaking booster check valve can cause low vacuum as well as the booster itself.
The check valve is a common part and is under $10 at most parts stores, it is also easy to change.
As for the booster, google: brake booster leak for information on how to diagnose , there is good information available such as thus one : https://www.quora.com/What-are-the-symptoms-of-a-leaking-brake-booster-vacuum
Hope this helps,
Good luck, let us know if you figure it out.
Carl Harr : Driver NASCAR Pro Series #2
1978 Gadabout-Restoring
1978 Palm Beach
1976 Glenbrook
Prevost Featherlite H3-45
|
|
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
