1969 FMX Trans Cooler Fitting Removal/Installation

While doing a radiator upgrade on my small block 1969 base with an FMX, I ended up needing to replace the trans cooler lines. Unfortunately that rearmost fitting into the trans is a real bear. I ended up removing the check valve and threading the flare fitting onto that before starting the whole assembly back into the trans, but after several hours of swearing at it with the car on ramps, it still leaks under running pressure.
I probably need to replace the check valve as well as the exposed threads were pretty rusty so there isn’t a whole lot of wiggle room on getting it sealed, but does anyone have any tips for getting access to those fittings? I ended up cutting down my 3/4" flare wrench to reach the big fitting, but overall access and getting things started is a nightmare. Is it better to drop the trans crossmember and keep the trans on a jack or what?


Tried all the same things on my 70 with no success. Finally gave up on replacing the rear cooler line, but now the fitting seeps fluid. Figured I would tackle that and a new rear mount when the tranny gets dropped. But 10 years later, the FMX is still working great. So I’m also interested in tips on replacing the rear line.

I emailed WCCC and they said the best way was to lower the rear of the trans for access, but to watch carefully and avoid crunching the top of the block back into the firewall. Need to get a new floor jack that I can go slow with and I’ll be replacing the check valve fitting at the same time.

Be sure to remove the radiator, fan and fan shroud first. Otherwise they get broken when you do this.

So the engine is pivoting on the motor mounts? Risk of damaging the rubber isolators?

If they are old and rotten maybe. In good shape they ought to be fine.

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Lowered the trans and replaced the check valve fitting, still have leaks under pressure. Guess I’ll try a flare washer or just remake these lines in NiCopp. Stainless lines are always a pain, should have made my own out of NiCopp from the start.