[heups1629]

I've been leaking a lot of Transmission fluid from my '69 LeMans - lots of fluid on the garage floor. I assumed it was the Transmission pan, but when I checked the fluid level today (with the engine running) I noticed a fast drip from this coupling (circled in photo). Is that a line that carries tranny fluid, and what is involved in repairing it? Thanks!

[Jeff Hamlin]

Yes those are the trans fluid lines but those couplings don't look OE,
at the least you can gently try to tighten up the connections to see if the leak subsides.
It looks like someone added them as a quick disconnect for trans removal at some point.
Worst case you will need to change out the lines.
I'm sure you can get pre-bent to accomplish this if needed.

[Aus Goat]

Have you added a trans cooler to the Auto or running a stock system?
Reason mine was leaking due to overflow with the extra volume the lines and cooler could hold.

[Scott Thelander]

it may be weeping because the line has a replacement rubber hose and dual
clamps as a repair of some kind...

You need a pair of original steel lines.. or at least 2 more clamps on that line
there is alot of fluid pressure and I have seen those hose to tubes leak on more than once...

if that rubber line is firm or hard replace it with quality napa hose ...

Scott

I have seen that coupler on several rebuilt trannys in the past...

I feel it may not be the coupler but the hose is weeping past the clamp..

also its been doing it under pressure because your tranny case is bare and clean

meaning heat and oil degreased it...

[Sirrotica]

If I were you I'd either buy new pre bent lines, or find a donor car to get some used lines from.

Those brass couplers have a habit of leaking especially when over tightened. The brass is so soft it deforms and after it deforms it will not seal again. I've been down the road before and usually after the cooling lines are cut and spliced they will leak. If not immediately, they will start leaking after some miles are put on them.

Lots of vibration and pressure on those lines. Unless you get a steel union intended for hydraulic systems you will have problems with leaks. Repairing the leak with neoprene hose usually will work for awhile, however since there are no barbs on the steel line they have a habit of blowing off the lines at the most inopportune times, even when double clamped.

This is a fairly high pressure line (60-100 psi depending on conditions) that is subject to a fair amount of vibration, twisting and pressure. Splicing it with fixes that will work on low pressure lines usually fail within a year or two, if not sooner.

If you decide to attempt the repair yourself, removing the transmission crossmember and lowering the transmission will give you a bunch more room to work on the lines. Someone that previously worked on the car cut the lines because they found it easier than undoing the factory connections due to limited working area.

One other thing is a leak in this area is also a safety hazard because of the close proximity to the exhaust. I have seen more than one fire caused by leaking cooling lines because a splice failed. My own car, 67 Le Mans was one of them. Transmission fluid has a lower flash point than thicker oils such as engine oil.

[heups1629]

Thanks for the responses. It sounds like I need to get that fixed pronto, for safety's sake. Is the name for that line a "Transmission Cooling Line"? This is a link to the part on Ames, (is this the correct one for a 350ci engine?). As far as I know, this is a stock setup.

https://secure.amesperf.com/qilan/De...A&web_access=Y

[69Farburd]

They are transmission cooling lines. They go from the trans and attach to the bottom of the radiator. The fittings it the photo look like the compression fittings you buy at the hardware store. As a temporary fix, you might try tightening the nuts on the fitting or replacing with a new compression fitting. However, I am in agreement with the others. I don't like the rubber lines back there. I am running an external trans cooler so I had to run a small section of rubber hose up by the radiator. Our local speed shop sells rubber lines made specifically for trans fluid but I flared the lines and used vey wide clamps to attach them.

[PontGuy]

Yes you are looking for transmission cooling lines. I replaced mine and it wasn't as difficult as I thought it might be.

My 69 Lemans came with a TH400 and the Ames link says they are for a TH350, so the ones in the link may not be correct. What trans do you have in the car?

[heups1629]

I have the 3spd Turbo Hydra-Matic transmission.

[Sirrotica]

T 400 and T 350 use the same lines, I've swapped T 400 in A bodies that came originally came with a T 300 2 speed or a T 350 to a T400 and the lines are the same. The only difference I have ever found is most lines are 5/16" and once in a great while you find a car with 3/8" lines. All you need to do is switch the brass connector that screws into the transmission housing to the other size, the bends are the same. Most all cooling lines are 5/16" and you'll have no problem with them.