Dropping the transmission to change oil cooler line?
G3GM :: G3 :: General Discussion
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Re: Dropping the transmission to change oil cooler line?
Yes, that's a good idea to flare the line and put a collar. I have seen it for fuel lines also.
I learned something else. This fitting may be called 1/2-20 instead of 1/4 NPS.
So if somebody want to buy a barb fitting in the future, the Hayden 393 should fit:
https://www.summitracing.com/int/parts/hda-393
Here is the full explanation:
A 5/16 tube has an inside diameter of 1/4. The nut matching the pipe has around 0.5 (1/2) in outside diameter and SAE 20 thread.
So to wrap up those 3 elements go together:


I learned something else. This fitting may be called 1/2-20 instead of 1/4 NPS.
So if somebody want to buy a barb fitting in the future, the Hayden 393 should fit:
https://www.summitracing.com/int/parts/hda-393
Here is the full explanation:
A 5/16 tube has an inside diameter of 1/4. The nut matching the pipe has around 0.5 (1/2) in outside diameter and SAE 20 thread.
So to wrap up those 3 elements go together:
- 1/4 inside diameter inverted flare
- 5/16 steel pipe
- 1/2-20 nut


76malibu- Donating Member
- Street Cred : 1
Re: Dropping the transmission to change oil cooler line?
Another fun fact: Despite GM's change to metric fasteners in the late 70s, the plumbing of my 1985 S10 is still all American. The transmission lines and connectors are just as described above, in fraction inches rather than millimeters. I've never worked on a newer GM car, so I can't tell you when the plumbing systems switched over, if ever, but on this July 4, we can celebrate the GM transmissions for preserving the new world values.

crice63- Donating Member
- Street Cred : 2
Re: Dropping the transmission to change oil cooler line?
I believe if it is an inverted flare fitting, it's going to be a standard thread. On the other side, if it's a bubble flare, it's a metric thread.
fasrnur- G3GM Enthusiast
- Street Cred : 9
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G3GM :: G3 :: General Discussion
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