Petcock rebuilding issue

[rustybronco]

Cycled the petcock yet again and its still dropless..Dale, I looked up that number and see its for that 5 hole gasket. You wouldnt happen to be able to measuer the OD of that oring and the thickness of it would you? Nothing in the spares box I have will work.

Chuck, I might have a few spares that I can send you.

[chuck hahn]

No leaks from the lever seal..just that oring on the diaphram seems to be too thick in the rebuild kits. One thats just a bit thinner around and still fits the plunger will solve the problem when i go to redo the Cooley petcock.

[Guest]

Steve, I think not paying enough attention to the o-ring sealing surface is what causes most petcock re-building to fail.

There was indeed quite a build up of garbage there. They also get pitted, I did polish my seat up trying hard not to get it out of round. Very critical for it to seal.

[chuck hahn]

Dale..PS. I wasted an entire afternoon tinkering with this. I will get that emblem adhesive off very soon.

[landshark]

Chuck Hahn,
I have a brand new aftermarket petcock (not a rebuild) that started to let fuel through after about 3-4 weeks. From all the tinkering we have done it seems that the O-ring is too small and doesnt seal enough, but i havent tried anything with stretching the spring.
Thanks for the thread, gives me another idea to try.

[chuck hahn]

Steve..I too took great care to be sure the screws were all started and let them self center the diaphram. Did this at least 4 or 5 times till I took the old 750 one apart and started comparing. I cant say with 1000% certainty the kits oring is too fat, but on the first try with the slightly smaller oring it sealed right up. I am very curious to tinker with this now..I just gotta know.

[Guest]

Steve..I too took great care to be sure the screws were all started and let them self center the diaphram. Did this at least 4 or 5 times till I took the old 750 one apart and started comparing. I cant say with 1000% certainty the kits oring is too fat, but on the first try with the slightly smaller oring it sealed right up. I am very curious to tinker with this now..I just gotta know.

Chuck,
The size of the O ring has got to fit snuggly. Don't believe I replaced any of those.

[chuck hahn]

Just came in like 5 minutes ago from the garage..its now been sitting for around 3 or 4 hrs and still no leakage. I know it needs to fit snuggly against the seat surface of the body. Thats my entire point about the size of the oring in the rebuild kit..its too big to let it slip into the seat properly without binding and its not seating enough to seal completely. I am gonna track down some orings and try them in place of the ones that are in the kit. My gut is telling me this is the issue.

[Guest]

Just came in like 5 minutes ago from the garage..its now been sitting for around 3 or 4 hrs and still no leakage. I know it needs to fit snuggly against the seat surface of the body. Thats my entire point about the size of the oring in the rebuild kit..its too big to let it slip into the seat properly without binding and its not seating enough to seal completely. I am gonna track down some orings and try them in place of the ones that are in the kit. My gut is telling me this is the issue.

Perhaps that will explain why petcocks rebuilt with those diaphram rebuild kits have such high failure rates.

[chuck hahn]

Buddy of mine Eric has a kit of Nitrile orings and i am gonna scrounge thru it and see if i can get what i think is the right fitment. If I put it in the Cooley and it seals first try, then i will get the other kit out and try their OEM one and see if it fails. Then swap back to mine again to see what happens. A few swaps back and forth and the story will be told!!!!!

[Dave8338]

Steve..I too took great care to be sure the screws were all started and let them self center the diaphram. Did this at least 4 or 5 times till I took the old 750 one apart and started comparing. I cant say with 1000% certainty the kits oring is too fat, but on the first try with the slightly smaller oring it sealed right up. I am very curious to tinker with this now..I just gotta know.

Let the rest of us know, as well. IF there is a kit that can be "had"(Duanne), I'm sure that MANY people would opt for this route.

For me...it isn't worth all the messing around. For a lot less than a good tire, I can have a NEW one that I've yet, to have leak.

[chuck hahn]

I will take DETAILED measurements and pics. I ordered the 2 kits from Z1 and they came in a K&L package.

EDIT...Nutthin knockin Z1 here..just sayin it was a K&L kit....

[Guest]

What about Robert Barr? He has got plenty of O-rings of all sizes, he might have that unique size your looking for and be able to source them.

[chuck hahn]

I will see what Eric has first.. If i find one then I will go from there.

[chuck hahn]

Just over 17 hrs and still not a drop on the cardboard. I say its fixed. Gonna get with Eric tomorrow and see what we can find in his oring kits.