Quic EGR test question

[k20]

Ok, trying to figure out the ongoing saga of why my truck runs rich. Pulled out the factory GM manual I got the other day, says check EGR. I know the test of pushing up on diaphragm yadda yadda. Well, damn replacement EGR onl has little holes on the bottom and I cant get my fat fingers in there. So another test it says is to grab the top and see if you can rotate it. Does it mean the diaphragm or the metal surround? I can move my metal surround from around 12 oclock to 3 oclock and back again. Whats the manual talking about?

 

[dyeager535]

Never heard of rotating anything to test EGR operation.

If it's easy access, disconnect the vacuum line, take something that WILL fit under the EGR, like an allen wrench, and suck on the hose. You should obviously be able to tell if the diaphram moves up like it should. It should hold in place as long as you keep the line blocked, and once released should return to "0" smoothly. Any "dragging" in the return would indicate the valve is sticky, likely from carbon buildup.