Have a 1999 V10 F250 with about 122K. Truck still runs like new. Over the 4 years I have owned it, when it's hot outside (usually over 100F) and I'm doing alot of stop and go driving, when I get home the transmission always leaks out quite a bit of transmission fluid onto my garage floor. It looks to be coming out the top of the transmission like maybe around a overflow hole. I have checked the level and all is good. Doesn't smell burnt or anything like that. Just curious if this a normal situation with these ford transmissions doing this? Thanks in advance.

Mike

 

There is a seal on the front of the transmission that when it gets hot it becomes more pliable and will release a bit of fluid. After it cools the seal hardens back to normal.

Let me quote FTE's transmission expert, Mark Kovalsky, from another post.

What's happening here is that the torque converter hub is getting very hot. That gets the hub seal hot, and unfortunately the stock seal gets soft when it's overheated. Now the fluid pressure that the seal is supposed to hold is enough to press past the softened seal and leak out of the bellhousing. Once the seal cools off it hardens and works again. The stock seal will do this heat/cool cycle several times before it finally fails for good.

If the trans is in good shape the trans can be removed and an aftermarket seal installed. The aftermarket seal works MUCH better at higher temps. That and better trans cooling should fix the problem.

The 4R100 did not have the greatest cooling. The hot setup (pun intended!) is to replace the air to oil cooler with a cooler from a 6.0L truck. That cooler will mount in the stock location using the stock mounts. All that needs to be done is to get some hydraulic fittings to adapt the 1/2" lines on the cooler to the 3/8" lines on the truck. If your truck has a trans cooler in the radiator, KEEP IT. It does a FANTASTIC job of cooling the trans fluid. The routing is from the front of the trans to the radiator cooler, then to the 6.0L cooler, then to the rear of the trans.

 

If it is coming out of the vent,then it is getting to hot.

Check cooler lines,cooler for restricted flow.

An additional cooler wouldn't hurt either.

 

I'm not entirely sure if your truck has it, but there is a pressure bypass valve in the transmission cooler lines near the transmission .

When the transmission is cold, the pressure is high and the bypass opens up. If the bypass is stuck open, the fluid won't go through the cooler.

FIX THIS QUICKLY.

 

There are two reasons the bypass could be open when the trans is hot. Either there is a bit of debris keeping the ball off of the seat or the cooling circuit is plugged. In neither case would I replace the bypass. It can be removed from the trans and checked for debris. If it's clean, but it back on and run a cooler circuit flow test.

To rin a flow test get two small buckets. Remove the line where it attaches to the rear fitting on the bypass. Put a hose on the line to give you more room. Put the hose in one bucket and start the engine. As soon as the flow is steady move the hose to the second bucket and keep it there for exactly 15 seconds then put it back in the first bucket and shut the engine off. If there is at least a quart in the second bucket it passes the test. If fluid is spraying out of the bypass most likely the cooler circuit is plugged.

 

so personnaly do you find the stock trans cooler sufficent for plowing or SC setup? if not what course of action do you reccomend for superior cooling?

 

A cooler from a 6.0L would be much better. Even better is that cooler along with a cooler in the radiator. The cooler in the radiator is the best way to cool the trans at low speeds.

 

Hate to resurrect an old thread, but this fits a problem I had today to a T. I drove home from a week of camping pulling my 9000 pound trailer. Came over Mt Hood so there is quite a bit of up and down, so transmission had to work a bit. I got home, parked the truck for about 5 minutes, then went to park the trailer next to my house. I have a VERY steep driveway, the back axle of the 35 foot trailer comes off the ground when I am "cresting" the driveway. About halfway up the drive, the transmission started leaking fluid onto the driveway (I didn't notice until I was all the way up). A couple hours later no leaking (not much leaked out as I noticied it right away and it only was leaking while running).

So, my question is since this is the first time this has happened, and I have learned a lot about how the transmission works in reverse today after much online reading, should I be okay to check the level and continue driving. Or, am I doomed to needing to have the seal (and maybe the transmission at 99.5K) replaced ASAP?

Thanks for any opinions.

RYan

 

If it isn't leaking once it cooled down the seal is working again and should be fine until the next time it overheats.

 

Thanks for replying Mark. It did not leak upon re-starting later. I have another camping trip this weekend and I am planning to give it a go and hold my breath. I will run it a bit slower and maybe I can alleviate the problem.

Ryan

 

Next time you are in a slow-moving situation like going up that driveway where it overheated, put it in 4x4LOW and don't lock the front hubs to keep it in 2-wheel drive. It'll be MUCH easier on the transmission .

If you have ESOF (electronic shift on the fly) look for the vacuum solenoid on the passenger-side inner fender, disconnect the electrical connector to it, and then put it in 4x4LOW. This will keep the hubs from locking, and give you a 2.9:1 gear reduction. MUCH easier on the transmission that way.

Oh, and install a temp gauge for the transmission and keep an eye on it next time you are working the transmission a bit. I bet that once you shut the truck off, the temp in the transmission sky-rocketed. Next time, with a temp gauge, if you leave the truck running for a while and let the temp come back down, you'll be much better off than just shutting it down and letting it cook

 

Thanks for the info, I will look to disconnect the ESOF as I do use 4-Lo but I am sometimes in and out of it for fear of damaging the 4wd system. As you can see from the picture below, it is not a long distance but it is a pretty tough back up job. Only takes me about a minute usually now but I am sure the transmission is heating up.

On the gauge issue, am I correct that a tuner would have the appropriate info on it? If I am going throught the expense of it I may as well look into a tuner.

 

Yes, you can use a tuner to look at the transmission temp, BUT - that's not full-time. You'd need one of those mount-on-the-dash electronic gizmos to display that info. I have an electric Auto-Meter gauge mounted below the dash. I'd trust that more than what the PCM sees.

 

to this day my transmission still leaks really bad when it gets hot in my 1999 F250 V10. I live in AZ and this time of the year it's super hot out here. I also have a gauge pod and trans temp when it starts to leak really bad is between 175F and 180F. Just the other day I drove my truck in 117F temperatures for 1 hr on the hwy, got to my destination and wow easily a half quart of trans fluid all over the ground. It sometimes leaks on the exhaust making smoke everywhere also. I haven't added any fluid to it since it leaked out. Just waiting for the trans to start slipping then I'll add more trans fluid to it. I'm thinking also besides the seal leaking when hot, I might have to much trans fluid in there. So far things have been good and as long as I don't go any far distances in 117F temps the trans is ok and doesn't leak.

Does anyone have any suggestions on a temp fix for this problem? I was thinking about trying some trans stop leak but wasn't sure if that's a good route to go.

 

Two quick fixes:

First, if it's overfilled it is going to force fluid out of the vent. Don't overfill the trans!

Second, change the air to oil cooler for a cooler from a 6.0L truck. If your truck doesn't have a trans cooler in the radiator, consider changing the radiator for one that does have a cooler. Route the cooler lines from the front of the trans to the radiator, then to the 6.0L cooler, then to the rear of the trans.