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I am working on replacing the radiator on my 1973 Hurst/Cutlass with an aftermarket from USRadiator. Everything went smoothly and it was a drop in replacement, except for the automatic transmission cooling lines. They thread in and fit fine, but both ports leak quite a bit out of the back of the brass fitting. What I mean by this leak is that it's not leaking out of the threads, but rather out the back of the brass piece (see picture). These did not leak on the old radiator.
We tried to use a flaring tool to re-flare the ends but this did not seem to do much. Our next thought is to buy new cooler lines. I also want to confirm this car has a TH400 transmission?
Are you asking if the TH400 is OEM stock to the car or you don't know if it's the stock TH400 in the car?
I believe there were two Oldsmobile 455 engines available for the Hurst in the 1973 model year:
The 455 L75 Performance Engine (270 hp) & the 455 L77 Performance Engine (250 hp). The TH400 was the only transmission available for both engines. L77 was the optional engine required if A/C was installed, I think?
Are the ports in the radiator correct for the flare tubing? If so, do the sealing surfaces have any irregularities?
I'll have to ask USRadiator. Anyone know where to get the exact spec of the flaring?
Originally Posted by Vintage Chief
Are you asking if the TH400 is OEM stock to the car or you don't know if it's the stock TH400 in the car?
I believe there were two Oldsmobile 455 engines available for the Hurst in the 1973 model year:
The 455 L75 Performance Engine (270 hp) & the 455 L77 Performance Engine (250 hp). The TH400 was the only transmission available for both engines. L77 was the optional engine required if A/C was installed, I think?
Thanks you answered my question, I just wanted to make sure OEM they came with TH400s
If the car has a 455, it's a TH400. If it has a 350, it's a TH350.
Now, step away from the teflon tape. Inverted flare nuts neither need nor want any sealer on the threads. The threads are not the seal point, it's the metal flare. Look in the fitting hole in the radiator and see if it has an inverted flare seat or not. You don't need to contact anyone, just use your eyes. If you can't get in to see, take a photo with your cell phone. Some aftermarket radiators come with NPT threads at the trans cooler and require separate adapter fittings to get to NPT. This is what an inverted thread seat looks like:
If the car has a 455, it's a TH400. If it has a 350, it's a TH350.
Now, step away from the teflon tape. Inverted flare nuts neither need nor want any sealer on the threads. The threads are not the seal point, it's the metal flare. Look in the fitting hole in the radiator and see if it has an inverted flare seat or not. You don't need to contact anyone, just use your eyes. If you can't get in to see, take a photo with your cell phone. Some aftermarket radiators come with NPT threads at the trans cooler and require separate adapter fittings to get to NPT. This is what an inverted thread seat looks like:
I'm not sure just looking at the port what I'm looking at if it's the inverted flare seat or not. It looks a lot like yours, and it looks a lot like the old radiator I'm replacing. Below I have pictures of the new radiator and old radiator.
I'm thinking that my cooler lines are not inverted flared and are just single flared and this may be the problem. I attached a picture of the tube flare as well. If this is the case I'm just curious as to how the single flare was working on the old radiator
Yes, those are correct inverted flare seats. Start by cleaning all the old paint and sealer and teflon tape out of the fitting and the tube and flare nut. Carefully inspect the flare on the tube for minute cracks or deformations. Your picture is not exactly in focus but it appears that the flare isn't perfect. You should not need any bandaids like conical washers or sealer.
to me , the inverted flare of the US Radiator is too wide to seal correctly , look at Joe's photo seems smaller diameter ..
I think perspective of the pics are playing tricks. Both radiators flare seats look to be about the same as Joes when looked at from the distance of Joe's picture. The USRadiator pic I took was really up close. I just received an inverted flare tool and will be cutting and re-double flaring the lines and will update
Circling back to this post for anyone in the future: The existing trans cooler lines were not correctly double flared. I bought replacement lines from inlinetube that had the correct double flare already and all is good
