Hi all,

Did some searching and decided it was best to get some opinions here. I have a 2005 Expedition, 5.4l 4x4, with about 130,000 miles on it. The transmission is original, and the truck has been overall well maintained. I'm the second owner, and I do believe the transmission has been serviced atleast 2-3 times, if not more, in it's life.

Anyway, about a week ago was doing a trip in it, and everything was fine - then the O/D light started to blink. I was on a busy highway, and didn't know right away what the blinking was indicating - but everything felt fine. I drove about 2-3 miles to a rest stop, where I pulled over. Once I got out, I saw the issue - one of the cooler lines had busted and leaked transmission fluid everywhere.

No doubt the O/D light was for an overheat condition due to low fluid.

I didn't drive the truck any further, and had it towed home.

I've ordered replacement lines, and will repair those and replace the fluid/filter in the process.

My main question is this - with the mileage it has, and the fact that it overheated but to an unknown degree (and drove steady for about 3 miles while overheated), do you think I have caused enough damage to warrant a proactive transmission replacement?

Of course, I don't want to spend the money on that, but if it's going to happen, I'd rather do it all at once since it's a great truck otherwise. Plus, after sitting at a rest stop for 2 hours waiting for a tow, and realizing I was lucky I wasn't on the side of the road, I'd hate to do it again for a toasted transmission a few months later. I've priced out the transmission to be between 1700-2000 and I do my own work.

Big question is - how much of an overheat can a 4r70 take, and survive long term, with 130k on the clock?

Appreciate your thoughts and opinions, and even first hand experience if you have it. I know these lines are an issue, so I'm sure I'm not the first to have a line burst while driving and find out due to the blinking O/D light warning of trans overheat.

Thanks in advance!

 

I doubt it overheated. Neither of us knows what code was set when the light flashed. My guess is that you set a code for a slipping condition due to low fluid.

Most likely it's fine.

 

Thanks! I'm waiting on the replacement lines from Tasca and will drop the pan and replace the filter before adding fresh fluid. Then will see how it performs. Thanks again

 

you can do that, but it's a waste. The filter doesn't need to be changed.

 

No need to drop the pan unless you want to inspect for debris. The filter only needs to get changed at overhaul, it's not really a filter but a large micron screen.

 

Thanks! Saves time and money if not needed.

 

In my experiences with automatic transmissions, if they still move then the fluid didn't get low enough to cause damage. A fluid change is likely all you need to do.