Brass into plastic threads leaking?

[squirrel]

what size is all this stuff? Is it 1/2" pipe thread? and 3/4" ID rubber tube? could you go to AN lines?

https://www.summitracing.com/parts/sum-220282b

[pdub]

what size is all this stuff? Is it 1/2" pipe thread? and 3/4" ID rubber tube? could you go to AN lines?

I've been shopping, and yes, -12 AN. I've seen that bulkhead at summit and I've seen this to go with it at pegasusautoracing:


I'll need a total of about 2 inches of thread on the bulkhead to pull this off and just ciphering on the photo of that bulkhead it'll be a mighty close fit in length. I asked Dan in a post above, how do I hold the nut on the inside while I tighten the one on the outside or will I need to hold it after it starts going together?

[squirrel]

holding the nut is fun....I put one in the gas tank on my 62 Chevy II, but I forget how I did it.

I think getting the thread length you need would be difficult.

Also, have you closely inspected the tank to see if there are any cracks at the threads?

and have you tried any other NPT fittings in the hole, to see if they will get tight? It could be the hole that's bad, or it could be the fitting threaded into it is not the correct size.

[anotheridiot]

there is always mcmaster to go full brass and get the NPT to AN, (or 37 degree flared fitting) in their terms.

[pdub]

holding the nut is fun....I put one in the gas tank on my 62 Chevy II, but I forget how I did it.

I think getting the thread length you need would be difficult.

Also, have you closely inspected the tank to see if there are any cracks at the threads?

and have you tried any other NPT fittings in the hole, to see if they will get tight? It could be the hole that's bad, or it could be the fitting threaded into it is not the correct size.

I'll admit that this morning now I see what y'all are talking about, NPT. Yep, that sure is one and I didn't even know about that stuff. I'll do a closer inspection of the tank for cracks, of course I haven't thought of that. I don't have any other NPT fittings to play with the hole, it's for sure the hole has gone bad because it all went together out of the blower box and it held for a mighty long time until it didn't.

[pdub]

there is always mcmaster to go full brass and get the NPT to AN, (or 37 degree flared fitting) in their terms.

Wow, do they ever they got STUFF. This is a low pressure system like a real big aquarium pump so I'm not really sure what I need as long as it doesn't leak. All I know is I don't want another plastic tank but I've got one on the way that might not ever get here.

[squirrel]

AN and 37 degree flare are different animals...they don't mate.

Take the brass fitting to the hardware store, see what size of pipe it matches. It's probably 1/2" but since I can't tell exactly what size everything is in the picture, I'm just guessing. Buy some other fitting with that thread size, then see how it fits the tank.

[pdub]

Ewwwwwwww the tank threads are in a horrible shape. Most so around the 6 O'clock (down) area.



Here's a better look at the fitting:

[pdub]

Here's what I believe is a showstopping deal breaker for the bulkhead procedure. The outside of the tank is curved where the hole comes through.

[squirrel]

That does look like 1/2" pipe thread.

If the plastic is worn away or distorted, then you'll not likely get the threads to seal again.

A -10 AN fitting would go through the hole in the tank if you drilled it to 7/8". -12 is 1-1/16" and is probably too big to fit. And then the problem of fitting nut inside, and the additional problem of giving it a flat surface for the washer to seal to.

Doesn't look promising.

[Beagle]

That does look like 1/2" pipe thread.

If the plastic is worn away or distorted, then you'll not likely get the threads to seal again.

A -10 AN fitting would go through the hole in the tank if you drilled it to 7/8". -12 is 1-1/16" and is probably too big to fit. And then the problem of fitting nut inside, and the additional problem of giving it a flat surface for the washer to seal to.

Doesn't look promising.

that's the other reason I wonder about gas ptfe tape - it's thicker than the water pipe spec tape. I was thinking a couple of wraps might close up the gap.

[SuperBuickGuy]

use metal to plastic 2 part epoxy. I dug around in my glue box last night but didn't find the exact stuff.... but with the threads on the fitting plus what remains of the threads in the container.... it should bond just fine.... pictures later...I wanted to do the wrench/nut bulkhead fitting but because the depth of the tank and obstructions, I couldn't.... the epoxy has been there, and in the sun, for at least a couple years... still water tight.

[corvettedad]

I'll throw my in, although this is not my field of knowledge, first considering the weight of the fitting, why not go with a plastic fitting with the yellow tape or with the o-ring idea. Either way it would take the weight/vibration out of the equation.

[squirrel]

the weight of the fitting isn't the issue...it's the pull from the hose that's attached to the fitting.

The epoxy trick, that SBG brought up again, still looks to me like the thing to try.

[squirrel]

also, teflon tape is more of a lubricant than a sealer. It allows the threads to get really tight, so they can seal. Do some research, see if I'm wrong (I could be)