Are liquid check valves rebuildable? - JeepForum.com
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post #1 of 16 Old 01-04-2014, 03:21 AM Thread Starter
DirtyCJ7
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Are liquid check valves rebuildable?

I am having problems with my CJ7 passing the required EVAP smog test. It has a GROSS Evap leak. We smok tested the system and found smoke bellowing from the rear left corner (roll over and liqid check valve) area. I am going to get into it tomarrow. I have found a few sources for roll over valves but cant seam to locate the LIQUID CHECK VALVE any where.

anyone know where to find a replacement?, Are They Rebuildable? if so, How?

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post #2 of 16 Old 01-04-2014, 04:42 AM
Matt1981CJ7
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The OEM style valve is no longer available, new.

They do come apart, and I suppose could be repaired, depending on what's broke.

Alternatively, I think you could use one of these.

Good luck,

Matt
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post #3 of 16 Old 01-04-2014, 05:46 AM
rbunch4468
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I've had mine apart due to curiosity during some sheet metal repair to the wheel well baffle. You might find it just needs a good cleaning. It is not all that different from a carburetor float. If liquid fills from the bottom (vent connections) the main body of the check valve floats to close the orifice on the top. Be careful dismounting it from the baffle. The plastic is old and can be very brittle.

I am not familiar with the CA Evap tests, but....I have a hard time understanding how this liquid check valve would change fuel vapor amounts since it operates as a 'normally open' valve. Check for a cracked plastic body, perhaps....as I mentioned it can be brittle.

One idea would be just to bypass the Liquid Check Valve altogether to see if the symptoms go away. Then you would at least have more information to determine if you need/want to replace it.

Next, I would check the vent hoses themselves for cracks.

For the smoke test, where do they pressurize the fuel system? Is there a safe way to emulate this while you check out the system?
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post #4 of 16 Old 01-04-2014, 05:57 AM
skizriz
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There is a good chance the o ring under the cap is shot.
Mine was just a few pieces of brittle broken rubber after 30 some years.

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post #5 of 16 Old 01-04-2014, 10:29 AM Thread Starter
DirtyCJ7
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Thanks all,
I replaced the fill neck and cap. in Cali they pressurize the system to about 5psi and it needs to hold. So the LCV is needed to hold back the pressure so it dose not vent. Info only.

I wonder if I modified with a PCV valve just to get thru the BS Cali Emissions... it's just expensive to keep re-testing, Err
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post #6 of 16 Old 01-04-2014, 11:06 AM
skizriz
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Sorry, meant the cap for the LCV.
Theres an o ring under the plastic cap to seal it up.

The LCV works just like a float in a carb. Air goes through, but liquid raises the float and closes the needle valve.

Its always open for venting, unless filled with liquid.

The Rollover check valve is metal and prone to rusting. Something else to look for.


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post #7 of 16 Old 01-06-2014, 10:08 PM
Colt44
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I also took mine apart when I re-replaced my gas tank, and there's not much to it. I think I mostly cleaned it out (two or three decades of gunk and debris), but seems like there was a spring and maybe an o-ring that I replaced on general principle. Sounds like you got it under control, It's a PITA, but if you ever roll your Jeep you might be real glad to have a working check valve.

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Some of us are looking at the stars."
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post #8 of 16 Old 01-07-2014, 05:35 AM
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Here's pics of mine, after I cleaned it.
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Fred
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post #9 of 16 Old 01-07-2014, 05:40 AM
Matt1981CJ7
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Fred,

Did you have to replace the o-ring?

Matt
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post #10 of 16 Old 01-07-2014, 06:09 AM
FLynes
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Quote:
Originally Posted by Matt1981CJ7 View Post
Fred,

Did you have to replace the o-ring?

Matt
No, mine was still very pliable, so I put some vaseline on it, while I was cleaning everything else out, then wiped it down and reinstalled it.

Fred
Retired Army Guy

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Lime Green
Black Wellington Vinyl Bench Seats
258 I-6 1bbl
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post #11 of 16 Old 01-07-2014, 11:07 AM
Tigerjeep79
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An o-ring for the fuel sender fits the LCV perfectly. It's advisable to put a little Vaseline on it (per FLynes), as the cap is a pretty tight fit. The LCV tends to be brittle with age, so be careful taking it apart.
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post #12 of 16 Old 01-07-2014, 11:46 AM
vinnyabs
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Wouldn't silicone lube be better than Vaseline as the petroleum will lead to break down of the rubber? Does it not matter on such a small issue/piece?

Earning an engineering degree one CJ7 hiccup at a time
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post #13 of 16 Old 01-07-2014, 03:50 PM
FLynes
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Quote:
Originally Posted by vinnyabs
Wouldn't silicone lube be better than Vaseline as the petroleum will lead to break down of the rubber? Does it not matter on such a small issue/piece?
I was always taught to use Vaseline, especially on o-rings inside transmissions. Maybe you know something I don't?

Fred
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post #14 of 16 Old 01-07-2014, 04:34 PM
ScroungerLee
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If the o-ring is meant to seal against gasoline and fuel vapors then my wild guess is that other petroleum products would be just fine
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post #15 of 16 Old 01-07-2014, 05:00 PM
vinnyabs
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Makes sense. Guess my father was right all those years. Vaseline does have more than one use!

Earning an engineering degree one CJ7 hiccup at a time
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