Hey guys, having a problematic 727 that keeps leaking fluid from the dipstick o-ring. I have tried several sizes with no luck.

My main question is sizing, does anyone know what spec is for id/od/thickness?

My other thought is material, i bought a bunch of different sizes from farm and fleet's o ring section, could the material not be compatible with the fluid, causing the leak? Last one that went in was a TIGHT fit, i thought i was good to go and it did not leak in the garage when test run, but first drive out on the road, stopped for gas, had a large puddle underneath.

Any help would be appreciated. John

What type of a "interferance" fit are you looking at ? ... ID of the hole vs the OD of the tube AND the OD of the O-ring installed on the tube?

Have a look at these aftermarket dipstick & tube assemblies.. Rather than use an O ring they use a formed rubber sleeve that eliminates any potential leakage...

http://chucker54.stores.yahoo.net/trststdi.html

what i mean is the factory spec for the o ring itself, id/od and thickness if it. That's how all the orings i have seen are measured. Thanks. John

It won't fit an early style tube.. The deal is for the 500/518 O/D trannies Mopar copied the GM design dipstick tube & seal... So they make a tube that works for smallblock 904's & 727's but the aftermarket copied that & made tubes to fit big blocks & hemis... Back in the 90's I bought the smallblock tube at the dealer & cut the tranny end off & welded it to a big block tube for my car... Lotta work but stopped the leak.. Now ya just gotta open the wallet...

well its going behind a late 80's small block ram, so it looks like the seal will work for me then, i will have to give it a shot. Thanks. John

The correct O ring is .750" OD X .100" thick. If repeated replacements don't stop the leak, look closely for a small crack in tube where it's beaded for the O ring. Repeated wiggling of the tube will often cause cracks there.

Thanks for that. I looked at the tube for cracks, even swapped to another I had, so I do not think its a crack that leaking, just the seals i am trying. Thanks, John.