It's about time to change the transmission fluid in my excursion again. I had transmission problems about a year ago(no overdrive or reverse that fixed itself one day) been shifting great for 20,000 miles. I have 150,000 miles on the original transmission. I'm afraid that if I change the fluid the problem may come back. Should I change the fluid or leave it alone. I've always changed it every 30,000 miles using ford atf since I bought the truck with 60,000 miles. If I change it what ATF should I go with? Fords ATF? Sythetic? What brand? Id like to put sythetic in it cause I'm running sythetic for every other fluid.

 

Changing the fluid is not going to hurt the transmission. If you already have problem, it is not going to solve it and vice versa. I try to flush mine between 30 and 40k and use the fluid the dealer recommends. I know lots of others use all synthetic. That would be a personal choice.

 

I recommend changing the fluid. Mobil 1 Synthetic ATF is my recommendation.

Here's how to change all of the fluid without a lot of work: Changing ATF Fluid in a E4OD and 4R100 transmission .: Articles

 

Well I guess I'll give it a shot and change it. While I'm there I'll go ahead and put the John woods valve body,+8 quart deep pan and the 6.0 tranny cooler in that's been sitting in the shop collecting dust.

 

I was hoping you would chime in. Thanks Mark!

 

When I had the transmission problem I brought it to the local ford dealer and they replaced the shift solenoid pack, which didn't solve anything. They then charged me to flush it which didnt fix the problem. Reflashed the PCM, still didn't fix it. Finally they told me that there's a clog in the trans and they recommend a full trans replacement. Drove it like this for months. One day pulled a friends 32 foot equipment trailer loaded down and when I got on the Highway it clicked into OD and worked great. Reverse worked great to. Been working great for 20,000 miles.

Im wondering if that clog will come back when I get the system flushed

 

Maybe drop the pan and see if there are any metal bits in the pan or anything in the filter.

 

I've never seen a clog in a transmission. I have been inside more than a couple of them. I can't think of anything that reverse and overdrive would have in common. Now if you had said reverse and third gear then the problem would be in the direct clutch.

 

It wouldnt go into overdrive at all and when you put it in reverse the trans would lock up. Full throttle in reverse and the truck wouldn't move an inch. It would just bog down and blow out a ton of black smoke. If you shut the truck off the restarted immediately then put in reverse it would work perfect every time. It was the weirdest thing I've ever seen a transmission do.

 

That is the forward clutch not releasing. That's not a common problem, it probably was a sitcky valve in the valve body.

 

So do you think I'll be safe changing the fluid Mark?

 

Here is what I wrote earlier in this thread. I don't see any reason to change my recommendation.