Exhaust air check valve needs replacing too often.

[Loobed]

My Exhaust air pump check valves keep going bad after about 35k miles. They freeze closed. They are made from stainless steel, so they cost more than the old plain steel type: $40+ ~vs~ $20-. When I unscrew them for replacement, they are full of water condensation. I can't see any rust inside the valve. I have tried to soak the valve in carb cleaner, MMO, Sea Foam, PB Blaster, Alcohol, WD-40, and Break parts cleaner. Nothing seems to free the stock valve. I will take one apart to see how it looks and works.

It is a 2001 GMC w/5.3L engine. It has 2 check valves: One per side. I am in Northern California, San Francisco Bay Area, East Bay. It isn't too humid

How long does the check valves in your GM, or other, vehicle last?

I am starting to wonder if the TCW-3 oil I put in my fuel tank is causing the check valves to plug. I have read that some 2 stroke oils can plug power valves with carbon, but there isn't heavy carbon build-up in the valve. The inside, from what I can see with a flash light, is clean. When I take it apart, I will get a better idea of how much carbon is in the valve.

 

[eljefino]

I've been reading about this common problem. Unfortunately I forget the fix.

I don't think it's your TCW3.

 

[morris]

is the engine running to rich? i have nothing against TCW3, but you might try mmo.

 

[Loobed]

Originally Posted By: morris
is the engine running too rich? i have nothing against TCW3, but you might try mmo.


It is computer controlled, and I just had it smogged, and it was/is running perfect. My friend hooked it up to his Snap-on scanner and said everything was good. I think it might actually be a little lean. I think long term trim was negative.

I don't want to use MMO because it has Phosphorus.

 

[KenO]

Delete it and get the ECU re-tuned. Problem solved

 

[JTK]

Do you do a lot of short trips? I know on other GM products, the build-up is from condensation laden exhaust back-flowing through the check valve.

Usually, if the engine gets well up to temp, or you do lots of steady highway travel, it's not a problem.

Joel

 

[mechtech2]

I doubt it's the TCW3.
Like mentioned, condensation from short trips is my first guess.

Maybe a halfway point cleaning [instead of waiting for them to totally puke] would work.

 

[Loobed]

I took it apart. It looked fairly clean. There was no carbon buildup. The only thing I can thing of is that the rubber seal swelled up. There isn't too much to these valves: It only has a spring and rubber seal sandwiched between two pieces of metal.

Pictures to come.

 

[Loobed]

here are the pictures

 

[dailydriver]

I replaced mine, but they probably were OK.

The code was set due to a faulty air pump, which was MY fault, as I drove through some deep water in a VERY poor drainage underpass. (It is mounted VERY low in my car.)

 

[Loobed]

Originally Posted By: dailydriver
I replaced mine, but they probably were OK.

The code was set due to a faulty air pump, which was MY fault, as I drove through some deep water in a VERY poor drainage underpass. (It is mounted VERY low in my car.)

There was a problem of water getting into low mounted air pumps and cracking if the weather got below freezing.