I managed to get myself a Harrison radiator for the Olds. It was original to that car and engine. It has been pressure tested by a rad shop and is OK to go. I have two brass fittings that I need to thread into the tranny cooling ports on the bottom of the rad. Do I use Teflon tape, or Loctite white thread sealant goop? What makes for the best, leak-proof, long-lasting seal?

edit: I need to find fittings that are 1/4-20 threads with a 3/8 hose nipple. Seems to be a specialized fitting. Any thoughts where to get two of them?

 

Original trans cooling lines are usually 5/16" flare fittings. Not pipe thread, or anything else. If you use 5/16 hard lines, as it came stock, you shouldn't need any other fittings, and with flare fittings, you don't need teflon tape or any other sealant. The flare is the seal.

 

If you want a hose barb just go to the hardware store and find the inverted flare fitting that works. I prefer Ace Hardware over Home Depot or Lowe's for hardware like that.

Remember that transmission cooler hoses need to be higher quality AN hose vs. standard quality vacuum/heater hose.

 

Thanks for that. So, the 3/8 hard line is incorrect. I could swap that out for 5/16? The lines are run kind of poorly anyway, thinking of starting fresh, with the flare fittings and the new tubing runs back to the tranny.

 

Also, I checked the threads for the two cooling lines on the bottom of the rad, and what I came up with is 1/4-20 threads. Does this sound correct? I want the hose barb fittings to match those threads.

Or, I could just ram the less TPI fitting into this rad and say screw it. The brass fittings that were in my aftermarket aluminum are 18 TPI and the threads that this Harrison rad accepts nicely are 20 TPI

 

The hard lines from the trans to the radiator use inverted flare nuts. On some radiators, these screw into adapter fittings that have female inverted flare and male NPT, with the fittings soldered into the end tank actually female NPT. On other radiators the inverted flare thread fittings are soldered directly into the radiator. If you have the former with the adapter fittings, yes use teflon tape or sealer on those NPT threads. Do not use any sealer on the inverted flare threads.

This is a photo of the female inverted flare fitting soldered directly into the radiator.

 

my issue is that I want to use the correct make thread. The threads for two cooler lines in the rad are 20TPI. I made something work I’ll post a picture and maybe I can get your guys’ feedback.

 

I used some heavy duty Binks fluid hose, and connected to the 3/8 green tubing. I used a die and cut 1/2-20 threads onto two 90° brass fittings. I used Teflon yellow tape on those threads and tightened them into the cooler line threads on the rad. No leaks. Would a person want hard line all the way to the rad, and, would a person want to stick to the 5/16 OD steel line from tranny to rad?

 

Steel transmission cooler lines were OE. You might be able to order some pre-bent depending on what Oldsmobile you own. If you decide to bend your own transmission cooler lines I suggest using copper/nickel over steel. Hard lines are always preferable over hoses.

 

Most factory set ups are all hard line. And o chance of rubber hoses bursting. If you do decide to use rubber, be SURE to use one that is for ATF! Other hoses can swell and fail!
You can rent a flaring tool at some auto stores, and make your own, as said, NiCopp is the easiest to bend and flare.

 

The standard threads on an inverted flare nut for a 5/16" hard line are 1/2-20. There's nothing to "make", that's the standard.

 

Joe, thanks for that. I am going to get some fresh 5/16 line and use those 1/2-30 flare fittings and get those lines back to how they originally came. Not sure of the routing, since they were changed from original, but I’ll figure that out. Shouldn’t be too tough to make the proper bends and keep the lines out of the way of everything.