How do you test EGR valve?

[GNRick]

My BLM's are 160 at idle, can't find any vacuum leaks by looking or listening...I was told to check the EGR valve, I guess because it must be a pretty big leak. It only has 180,000 miles on it, can't believe it could possibly fail now:wink: So how would I check it for a vacuum leak? Could the bolt holding it down just be lose? Thanks.

 

[ngnowner]

I know of 2 ways, first if you have a handheld vacuum pump and gauge unplug the egr valve line downstream side of solenoid, and use pump to pull down a vacuum, observe gauge it should hold steady. 2nd, unplug line at egr valve and cap it, see if your #'s improve? There is a third way I believe also with engine warm and running crack throttle plate slightly while touching underside of egr valve, it should start to retract into pot. hope that helps

 

[GNRick]

I know of 2 ways, first if you have a handheld vacuum pump and gauge unplug the egr valve line downstream side of solenoid, and use pump to pull down a vacuum, observe gauge it should hold steady. 2nd, unplug line at egr valve and cap it, see if your #'s improve? There is a third way I believe also with engine warm and running crack throttle plate slightly while touching underside of egr valve, it should start to retract into pot. hope that helps

Here's what I did...I removed the hose from the EGR which I suspected was not working. This car has 180,000 miles on it. Probably original valve. Then I attached my mityvac to the EGR and pumped it about 3 times. Nothing happened. Idle didn't change. So then I went to my other GN with only 25,000 miles on it. I hooked up the mityvac and after one pump the engine almost died. After the second pump, smoke started coming out from somewhere around the header. So would you say I have a bad EGR valve? If so, how difficult is it to change it? I have an extra but it is a Wells unit and I don't have a gasket for it. Should I stick with GM or is Wells ok? Do I need a new gasket? Thanks.

 

[turbofrank]

Try the Wells and yes on gasket
Not hard to r/r think i used a claw wrench for easy access have a magnet handy in case you drop the nut in the intake as i did.

 

[petty]

My BLM's are 160 at idle, can't find any vacuum leaks by looking or listening...I was told to check the EGR valve, I guess because it must be a pretty big leak. It only has 180,000 miles on it, can't believe it could possibly fail now:wink: So how would I check it for a vacuum leak? Could the bolt holding it down just be lose? Thanks.

Just remember that while you check the plunger movement, if it opens and closes then the EGR valve is working fine. It doesn't open and close, then it's either that the valve is failed or the plunger is sticking. Clean and remove it.

 

[turbojd]

If the EGR doesn't hold vacuum, you probably have a leaky diaphragm, as said above check for in and out movement, check vacuum hoses, inspect the egr little filter in the solenoid. The EGR is simple to change, 2 bolts and a gasket. My EGR had carbon build up in the port which I cleaned out before reinstalling the egr valve.