KinneyD

I have a 1966 Mustang with an automatic C4 transmission in it. The transmission has been running well for the duration that I have had the car (4 years) with no visible leaks. I left the car sitting for roughly 1 1/2 weeks wile I was on a business trip. Upon returning, I noticed a major transmission fluid leak. The leak appears to be coming from the front driver's side of the transmission. I am a novice to this and am trying to learn as I go. Can someone please direct me in the correct direction to begin to troubleshoot this problem.

67LimeCoupe

First thing to do is get it up on jackstands/lift/ramps and take a look at it, most C4s will tend to leak from the fill tube area or from around the pan. I'd wipe it off and leave it for a day to see where its coming from exactly, otherwise its probably the shift linkage, they are notorious for being loose (pretty sure there was a post on here about how they came like that from the factory), IIRC you need to remove pan, filter, and valve body to get to the linkage and from there you can grind down a bracket or something to make it seal properly. A search might turn up a thread I read a while back regarding this issue.

Mark Hone

KinneyD: There is a "O" ring (I think it is actually a "D" ring) on the shifter linkage inside the trans on the right side that often starts to leak but does require the removal of the pan and valve body to get at. Mark

bop11

Check that the coolant level in the radiator has not gone down. The transmission coolant pipe in the radiator can crack and allow antifreeze into the transmission fluid. Also check that one of the pipes from the transmission to the radiator has not been rubbing against something and caused a leak.
Had a '73 Ford Pinto once, where Ford had dressed the transmission coolant lines against a frame member. The line rub through causing a pinhole leak. Fortunately, it pissed it up on the exhaust and generated smoke. No fire (although with that car it might have been a blessing) but generated enough smoke to be noticed quickly so I did not run the car out of transmigration fluid. Ford had a repair kit for this problem with a part number that cost $0.75 at the dealer, which made me think that they knew it would happen. Dealer confirmed that they made a whole lot of dollars replacing transmissions from this. The kit contained a short piece of 1/4" id hose and two clamps. Since the flow to the radiator is on the low pressure side of the pump, this repair did the trick.

sprog

yeah mines is leaking where the shift lever goes into the transmission. Parts are seal and oring. But u have to drop vale body out to get to them.

fastbackford351

It's not leaking...it's just marking its territory.