I have a 2000 F-150 with 7700 lb package (former light duty F-250). It has an AT with towing package and HD transmission cooler. Last week my wife and I were driving around Houston (hot as hell) for several hours and the tranny started slipping badly. I pulled over and tranny fluid was dumping on the ground. I had it towed to a mechanic, he said he has seen it several times and that it is a main seal leak that occurs only when very hot and then re-seals itself. This makes no sense but it is not leaking now. Someone told me that there is a pressure relief valve that opens when it overheats. This makes more sense but makes me wonder why the HD transmission cooler couldn't handle this when we weren't even pulling a trailer. Any experience with this and what you did to make sure it doesn't happen again?

 

When was the last time it was changed? The fluid does lose its ability to protect from wear and heat. If it isn't dumping it now I would keep an eye on it but plan on a rebuild soon!

 

i agree with you mechanic when it gets very hot a worn or dry seal will leak i have seen it many many times and the same thing with the trans drive shaft seal did you get a good look at where the fluid was leaking from. also when it cools off the leak stops. good luck

 

could it have overheated and came out the vent tube? i have seen the cooler plugged, causing the trans to overheat, making fluid come out of the vent and all over the bottom side of the trans from the pan to the extension housing seal, the other tech thought that it need a service and a rear seal... it came back the next day... trans over temp code, looked at temps on the cooler lines, and sold an external cooler to cust. it fixed the prob.

 

That's actually quite common. He's right.

That person has no idea what he's talking about. He's just making things up that sound right to him with his complete lack of knowledge of how a transmission works.

You probably have something wrong with your trans cooler. It could have debris either inside or outside, blocking the airflow or the trans fluid.

 

Thanks for the feedback.I am wondering about the transmission cooler being plugged as well. I will have the temperature of the fluid and the cooler tested the next time I take it for a reasonably long ride.

I had not changed the tranny fluid before (truck has 59K miles) but now have new fluid after the dump. I am going to change the tranny filter and fluid pretty soon

 

2001 Lariat 4x4/ 7700/125000 kms.

Had the same problem,tranny was rebuilt 3 years ago @ 70000kms,just after the warranty was over,with better parts and a better oil cooler, I was told.Last month noticed oil dripping underneath.Checked it out and was down 3 quarts.It was coming out from the torque converter area.Topped it up and washed it down and no leaks. "GO FIGURE" Wondering if I should investigate furthur? I probably would of traded it,just put 4 new tires on.