Does anyone know how important the anti-backfire valve is? Mine was leaking when I got the car, so I pulled it off and blocked off the EGR valve at the intake manifold. It is a 1987 GL wagon, EA82, carbed, 5Sp D/R 4WD. I am fixing and replacing all gaskets and seals as I find them. I found a leak under the intake manifold this weekend, new gaskets cost $3. One of the bolts broke off in the head. It took 3 hours to pull the bolt out without messing up the head. I have been doing all the repairs to get rid of a backfire. Everything I have done has not fixed it. The backfire has dropped a lot but, it still pops pretty good when I am getting on the hiway and get the RPM's up there. Any help would be very nice. I am at my whits end.

it's like an appendix, keep it until it goes bad, then get rid of it!

Your backfire is due to exhaust leaks or Air Suction Valve failure. The anti-backfire valve is a red herring. It's there to prevent the very slight pops you get durring closed throttle down-hill coasting. It does nothing when accelerating.

 

Replace your exhaust gaskets at the heads, and block the ASV's on both heads. Quarters in the inlet pipes work great. Cheap fix. You may have some leaks in your y-pipe as well, but blocking the ASV's will eliminate the backfireing as there will be no fresh oxygen to burn with the fuel.

 

GD

My 87 did that until the end, with new exhaust, etc. I didn't have a book to know there was a backfire valve :cool: . As lean as it ran (35-40+ mpg) There was carbon on the tailgate after long trips and was good on oil. Somethin in there lets stuff fly after the miles!

One of the bolts broke off in the head. It took 3 hours to pull the bolt out without messing up the head.

my favorite trick is to weld a nut on top of the stud. then you can use a socket to get it out.

Thank you. I just have one question, where is the Air Suction Valve located?

 

Thank you so much. I found the ASV, and put a quarter under each side, now I can hear while shifting. that was the best fifty cents I ever spent.

 

Yeah - that's got to be one of the best subaru tricks ever. We need an all-time greatest subaru cheap fixes list. That would be up there near the top I think.

 

GD