View Single Post
Old 06-19-2013, 02:56 AM   #46
Registered User
Join Date: Jul 2011
Location: Charlotte NC
Posts: 2,747
My Ride: 2001 BMW 330ci
The primary issue with the SAP is caused by two things:
- the check valve in the vacuum system needs to be replaced occasionally
- the solenoid that controls the air flow to the SAP valve needs to be removed, and cleaned with electronic parts cleaner
These two items are the source of the issue in most cases. The solenoid actuates the valve to open it. When it deactivates, the vacuum in the line needs to bleed off rapidly, to close the valve. The check valve in the vacuum line to the solenoid is what causes the vacuum to bleed off. If the SAP valve does not close immediately, because the vacuum is not bleeding off, the valve stays open, and exhaust gasses blow through the valve, and into the pump. This will kill the pump eventually.
This Seafoam procedure does not address the root cause. It simply cleans out the valve, and the cycle starts again. If you pull off the hose from the pump to the valve, look inside the hole, and see soot from engine exhaust blowing past the valve, then you need to replace the check valve, and clean the solenoid. Replace the rubber hoses as well. If the system is working normally, you should see a nice, clean valve when you look inside there. Anything else is a sign of a larger problem that will eventually kill your SAP.
Another sign of a failure of the vacuum actuation is if your hose from the SAP to the valve is degrading. It should be firm, and hard to compress. Check the large vacuum line from your brake booster for reference. They should feel the same. If it is degrading, it is because of exhaust gasses blowing by a SAP valve that is not closing in time to prevent exhaust gasses from back flowing into the pump. I have seen many people advise replacement of the hose, but a degraded hose is a symptom of another problem.
The fix is fairly cheap, but a bit labor intensive, due to the location of the solenoid and the check valve. If you want to save your $400 SAP pump, I would advise dealing with the problem, rather than treating a symptom (dirty SAP valve).
Also, it is much easier to just remove the valve, and clean it with brake cleaner, rather than pouring Seafoam in your engine. You can also access the port in the head with the valve off, and clean it as well. BUT, you need to deal with the root cause of the problem, in addition to cleaning the valve.

Last edited by MJLavelle; 06-19-2013 at 03:38 AM.
MJLavelle is offline   Reply With Quote