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Author Topic: Rollover Valve Rebuilding?  (Read 2742 times)

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Offline MIPS

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Rollover Valve Rebuilding?
« on: May 12, 2019, 12:27:13 AM »
While dropping my tank today I found that both hose ports on my vapour rollover valve had rusted off. I've been unsuccessful locating an OEM replacement and the Volvo/Delorean replacements are more than a week out if I buy one for $30 online. Has anyone rebuilt or re-stemmed the valve before?
« Last Edit: May 12, 2019, 12:27:29 AM by MIPS »

Offline MIPS

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Re: Rollover Valve Rebuilding?
« Reply #1 on: May 12, 2019, 06:32:50 PM »
I got impatient and decided to just rebuild it. It's pretty straightforward so follow along below.

This is your typical Rollover valve at this point. One or both of the line stems have rusted off and you have multiple pinhole leaks. Mine is also stuck closed. This is still a reusable unit.

1 - Clean the assembly with a wire brush or wire wheel.
2 - Bend back the two tabs that hold the valve to the mounting bracket and lift the valve up and out.
3 - The unit is press sealed shut with a folded lip over one of the two halves. Put the valve in a vice and carefully bend the circular lip back to separate the two halves. A thin fiber gasket will be broken in this step. This is okay for now.
4 - One half of the unit can now be put aside. For the other half you need to separate the valve chamber from the outer assembly which is press fit together. Carefully clamp the valve chamber and using a very fine flat blade screwdriver locate the edges of the mating surfaces and pry them apart, working around the entire unit slowly and trying not to bend the mating surfaces. You will wreck another gasket here as well. That's okay. They are unobtanium anyways.
5 - With the valve chamber separated the plastic valve and a ball bearing will come out. You have now completely disassembled the valve.

6 - Clean the unit again (and all internal components) and remove all the dirt and rust. If you are replacing the stems use a hacksaw to cut them off flush with the valve body and remove any burrs. I purchased a short 8" length of steel fuel line with a flaring on each end. I cut both ends off leaving the flare and an inch on each side, then fed the new stem pieces through the inside of the valve body and tacked it in place with a weld. You can then seal around the stem using JB weld. This is also a great time to locate any pinhole leaks on the valve body.

7 - After the epoxy sets, apply a thin film of RTV sealant to the mating surface of the valve chamber. You do NOT need a lot. If you still have a good and unbent mating surface this is enough to reseal the unit without the previously mentioned fiber gaskets.

8 - Install the valve and the ball bearing. You will always be able to know which half of the valve is the bottom as it contains a dimple which centers the ball bearing. The top half is flat.

9 - reassemble the valve chamber. It might take a few tries but you should be able to have both the ball bearing and the valve freely rattling around inside. Hand press the two pieces together then use a vice and a 7/16" socket to press the two parts back together completely. IF you were as minimal as I was with the RTV, it shouldn't ooze out at this point and make a mess.

10 - Apply another thin layer of RTV to the other mating surface.

11 - Assemble the two halves together and then using a hammer and small drift bend the lip back over the flange. Remember that the stems should be pointing 180 degrees from eachother and the two halves should not be loose or rotate, otherwise the valve will leak.

The unit  is now cleaned and reassembled. If you blow through either port and tip the valve upside down the valve should close. IF it doesn't then you have a stuck or poorly seated valve due to an improper cleaning and will have to dismantle the valve again before the RTV sets.

From here you can reinstall it in the bracket and bend the tabs back over however to get that extra ten more years of life out of the valve I'd paint it to keep the rust in check.

« Last Edit: May 12, 2019, 06:38:04 PM by MIPS »

Offline trucker79005

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Re: Rollover Valve Rebuilding?
« Reply #2 on: May 21, 2019, 11:45:16 AM »
Great write up! Not sure if I need to do that or not but loving the info.
Laura (Shorty)
1978 AMC Concord 2DR Hatchback w/ Ralley package
1983 AMC Eagle Wagon Limited w/ 5 speed
1971 Ford F250:)

Offline Taylor

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Re: Rollover Valve Rebuilding?
« Reply #3 on: May 21, 2019, 07:57:56 PM »
Excellent write up on a part that I didn’t even know was there.
Now I can add that to the repair and replacement list when I remove the fuel tank to fix the cancer that is above it.
2010 Toyota Rav4 pack mule, totaled 3/26/24 rear ended REAL HARD. concussion and whiplash. not fun
1999 Ford E250 conversion/work van 238,000 see if it will make 300,000
1985 AMC Eagle Limited Wagon 🖖🏼🦅
2020 Honda Africa Twin, the long haul trucker


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