1985-1996 Fleetwood and Brougham Forum Discussion, vacuum question in Past Cadillac Vehicle Discussion; 1990 Brougham. Is the vacuum system a closed system? Is a leak anywhere a leak everywhere? ohio boy...
- 10-03-13 04:25 PM #1Cadillac Owners Member
- Automobile(s): 1990 brougham
- Join Date
- Jul 2012
1990 Brougham. Is the vacuum system a closed system? Is a leak anywhere a leak everywhere?
- Sponsored Links Remove Advertisements
- 10-03-13 05:06 PM #2Cadillac Owners Master
- Automobile(s): 84 Coupe w/500
- Join Date
- Jan 2008
Olds 307? A leak at the back of the intake manifold will be a leak everywhere. I believe there are three different vacuum systems in the car but they all need a steady manifold vacuum. I believe emissions, hvac and engine accessories are all separate from each other. I could be wrong, emissions and accessories could be together.
- 10-05-13 05:35 AM #3
Re: vacuum question
On the 307, the emission controls system is tied into accessories like the ILC and vacuum brakes; the ILC helps stabilize the engine idle when the A/C compressor or alternator is causing a strain, and the vacuum brakes prevent engine run-on (dieseling) when the engine is turned off. The cruise control is mostly a stand alone system, but its vacuum source is spiced into the line going to the vapor canister.
Basically, if you have a leak anywhere in the system, it will cause some decrease in performance. Also, if you have a leak in the system, you can be almost guaranteed that there is another leak somewhere else, and you should just replace all the vacuum lines.
Here is a vacuum diagram: