Power Valve Leaking?

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May 4, 2006 | 10:06 AM

Troy77+79

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From: North Carolina

Power Valve Leaking?

Being as I still haven't had time to do the head work on my truck,

I figured I'd take the carb off and dump the fuel out to keep it from gumming up. I rebuilt the carb when I first bought the truck (Oct. of '05). Anyway, I decided I'd remove the power valve so I could spray some carb cleaner in the bowl (didn't want it to damage the rubber part of the valve). When I pulled the cover off of the valve, it was full of gas.

I thought it was supposed to stay dry, so the vacuum of the engine would operate the valve when needed? I started to go ahead and buy a new valve but thought I'd make sure that I'm not losing my mind as far as how the valve works. Hate to buy a new part if this one's still OK (even though they are pretty cheap).

Thanks guys.

Almost forgot, this is a '78 F150 351m 2150 carb.

May 7, 2006 | 09:24 AM

Putt

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From: Colville, Washington

The threaded end of the PV will have fuel around it, the hex end should be dry that is where the vacuum actuates the valve.

May 7, 2006 | 05:39 PM

Troy77+79

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From: North Carolina

Quote:

Originally Posted by Putt

The threaded end of the PV will have fuel around it, the hex end should be dry that is where the vacuum actuates the valve.

Thanks Putt, that's kinda what I was thinking. The cover that goes over the hex end was full of gas, went everywhere when I removed the four screws holding it on. I've tried blowing air against the valve while holding it in my hand and it doesn't seem to leak. I'm wondering if maybe I didn't have it screwed in tight enough and the vacuum pulled gas around the gasket. Does this sound likely? Any other way to test one of these things?

May 7, 2006 | 06:16 PM

kotzy

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You will know if that power valve leaks, black smoke out the tail pipe and lousy gas
mileage.

May 8, 2006 | 08:37 AM

Putt

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From: Colville, Washington

Well it is possible the gasket leaked, were there any rips, tears etc in the gasket? There are tools for testing, but kinda expensive if only doing your own carbs. I would replace the PV and make sure to use the correct gasket, it should come with the valve. Kotzy is right on with the black smoke and poor fuel mileage, too.

May 8, 2006 | 02:02 PM

Troy77+79

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From: North Carolina

There weren't any tears in the gasket, but it seems there was two gaskets in place. One stayed stuck to the carb, the other to the PV. I guess it could have been one gasket that seperated in half but both are so smooth that it really looks more like two gaskets. I don't think I would have put two on there, but you can't never tell.

I tried to order a new PV from O'Reilly's but they said they would have to charge shipping on it because it was a special order part. With shipping and tax it would've been over $12.00. Entire kits are around $20.00 but I don't need the rest of the kit, and when I did I'd probably need another PV by then.

Anyone know a chain store that does sell PVs without shipping charges? I haven't tried Napa or Carquest yet, I may check with them.

Thanks for the advice.