Fuel Filter O-Ring... Leaking
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Joined: Feb 2008
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Fuel Filter O-Ring... Leaking
Hey all -
I am having trouble with the fuel filter o-ring that sits top center over the engine. I replaced my fuel filters this summer and the first o-ring was leaking so bad that I had fuel on the ground beneath my truck. I replaced it with a new one thinking that I may have over-tightened and flattened it out but I am running into the same problem again. It's not dumping fuel out of the housing but I can see "wet" around the cap and I can smell diesel after driving a bit. Am I over-tightening, under-tightening? I don't see any apparent damage to the fuel filter housing itself and the cap appears to be in good shape too.
Any tips would be appreciated.
I am having trouble with the fuel filter o-ring that sits top center over the engine. I replaced my fuel filters this summer and the first o-ring was leaking so bad that I had fuel on the ground beneath my truck. I replaced it with a new one thinking that I may have over-tightened and flattened it out but I am running into the same problem again. It's not dumping fuel out of the housing but I can see "wet" around the cap and I can smell diesel after driving a bit. Am I over-tightening, under-tightening? I don't see any apparent damage to the fuel filter housing itself and the cap appears to be in good shape too.
Any tips would be appreciated.
Posting Guru
Joined: Jun 2012
Posts: 1,171
Likes: 2
You probably cracked the cap, particularly if you used the 1/2" indent with a ratchet rather than a wrench on the hex. Common problem, you can get a new cap at the Dealer, or a billet aluminium one on-line at different places.
Brian
Brian
Lead Driver
Joined: Jun 2007
Posts: 6,757
Likes: 5
From: Corvallis, OR
Make sure the cap is seated all the way too. If you're just going by the torque spec, sometimes the o-ring drag fouls it up if its not lubed well. I ignore the spec on oil and fuel caps now, tighten until it fully seats and you're good. You can feel the difference between the o-ring drag and when it stops solid when seated.
Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 25
From: Middle Tn.
Make sure the cap is seated all the way too. If you're just going by the torque spec, sometimes the o-ring drag fouls it up if its not lubed well. I ignore the spec on oil and fuel caps now, tighten until it fully seats and you're good. You can feel the difference between the o-ring drag and when it stops solid when seated.
Fleet Mechanic
Joined: Nov 2003
Posts: 1,372
Likes: 14
From: West Cornwall, CT
O-rings need clean and scratch-free filter caps and housings to seal properly.
Look closely at the housing where the o-ring would seal. If there are any gouges or scratches that would go across the o-ring sealing surface, polish them out with some emery cloth. No matter what, clean that suface and the one on the filter cap.
Next, lubricate a new o-ring with engine oil. and install it in the cap groove. Install the filter and cap in the housing.
Tighten the filter cap until the housing and cap surfaces touch each other. There is a torque spec for this assembly, but those two surfaces need to touch each other. The o-ring provides the seal. The torque spec just prevents the cap from becoming loose during operation.
If you do the installation as described above and *still* have a leak, then there is a crack somewhere. A close check of the cap and housing would find this. Cracks are rare. Most likely you just have some dirty or scratched o-ring sealing surfaces.
From a guy who has dealt with o-rings for years.....
Lou Braun
Look closely at the housing where the o-ring would seal. If there are any gouges or scratches that would go across the o-ring sealing surface, polish them out with some emery cloth. No matter what, clean that suface and the one on the filter cap.
Next, lubricate a new o-ring with engine oil. and install it in the cap groove. Install the filter and cap in the housing.
Tighten the filter cap until the housing and cap surfaces touch each other. There is a torque spec for this assembly, but those two surfaces need to touch each other. The o-ring provides the seal. The torque spec just prevents the cap from becoming loose during operation.
If you do the installation as described above and *still* have a leak, then there is a crack somewhere. A close check of the cap and housing would find this. Cracks are rare. Most likely you just have some dirty or scratched o-ring sealing surfaces.
From a guy who has dealt with o-rings for years.....
Lou Braun
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Fleet Owner
Joined: Apr 2012
Posts: 27,307
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From: Spanaway
Make sure the cap is seated all the way too. If you're just going by the torque spec, sometimes the o-ring drag fouls it up if its not lubed well. I ignore the spec on oil and fuel caps now, tighten until it fully seats and you're good. You can feel the difference between the o-ring drag and when it stops solid when seated.
prevailing torque. What you do is measure the torque required to turn the
nut/cap and you take that amount and add it to the torque spec and that gives
you a new torque value. This should put the cap on at the right torque.
Make sure to use engine oil to lubricate the O-ring. The worst thing you can use
is vaseline it degrades rubber and may not be compatible with the plastic of the cap.
To everyone that says that vaseline is ok look at the black goo that you find
where it has been used. This is the rubber being dissolved by the vaseline.
What is prevailing torque?
This term is typically used for locking type fasteners. It means that some torque
is required always, to turn the nut or screw. If you have a simple hex nut on a
screw, the "prevailing" torque is zero when the nut no longer contacts the surface and
therefore is loose and can come off. If you use a prvailing torque type of nut
(interference threads, plug of nylon in the threads or top), even if the nut backs off,
some torque is required to further loosen it so it is less likly to fall off.
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Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 25
From: Middle Tn.
What Cartmanea is taling about on the drag that the O-ring creates is called
prevailing torque. What you do is measure the torque required to turn the
nut/cap and you take that amount and add it to the torque spec and that gives
you a new torque value. This should put the cap on at the right torque.
Make sure to use engine oil to lubricate the O-ring. The worst thing you can use
is vaseline it degrades rubber and may not be compatible with the plastic of the cap.
To everyone that says that vaseline is ok look at the black goo that you find
where it has been used. This is the rubber being dissolved by the vaseline.
What is prevailing torque?
This term is typically used for locking type fasteners. It means that some torque
is required always, to turn the nut or screw. If you have a simple hex nut on a
screw, the "prevailing" torque is zero when the nut no longer contacts the surface and
therefore is loose and can come off. If you use a prvailing torque type of nut
(interference threads, plug of nylon in the threads or top), even if the nut backs off,
some torque is required to further loosen it so it is less likly to fall off.
prevailing torque. What you do is measure the torque required to turn the
nut/cap and you take that amount and add it to the torque spec and that gives
you a new torque value. This should put the cap on at the right torque.
Make sure to use engine oil to lubricate the O-ring. The worst thing you can use
is vaseline it degrades rubber and may not be compatible with the plastic of the cap.
To everyone that says that vaseline is ok look at the black goo that you find
where it has been used. This is the rubber being dissolved by the vaseline.
What is prevailing torque?
This term is typically used for locking type fasteners. It means that some torque
is required always, to turn the nut or screw. If you have a simple hex nut on a
screw, the "prevailing" torque is zero when the nut no longer contacts the surface and
therefore is loose and can come off. If you use a prvailing torque type of nut
(interference threads, plug of nylon in the threads or top), even if the nut backs off,
some torque is required to further loosen it so it is less likly to fall off.
Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 25
From: Middle Tn.
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