Mercon wasn't around back in the early 90's, but it came out around 98 so that's when it was introduced. This transmission has a weird converter clutch that slips and likes MERCON V to help it slip. It doesn't always cause trouble but never hurts in these trannys. I have seen it used in the older ones with no trouble at all, just don't use it in a E4OD. I believe there was also a TSB that says to use MERCON V in all the older 4R70W's too. Do what you want, it's just my reccomendation.

 

Well, it seems my new guage may be off by as much as 70* too high. After running the truck til the guage read 210*, I used a infrared thermometer to measure temps at different locations. First I tested it on the thermostat housing, and it read 183* (I have a 180* thermostat just installed). Looking at the trans fluid input @ the radiator, the temp read 174*. Looking at the radiator output, it was about 165*. At the sensor for the guage, the temp was 145*. And finally, at the output of the trans cooler, the temp was 135*. The fluid circuit goes like this: output from tranny to input on radiator, to output of the radiator to the input of the bypas filter, through the temp sensor to the input of the cooler to the output of the cooler and back to the tranny. So it started at the radiator input at 174*, and returned to the transmission at 135*.

I need to do more testing, but the guage seems to be way off. I wanted to update you. I will post results more later.

Thanks,
John

 

John, your seeing many of the same things I saw.
I would spray paint the measureing areas flat black so your infrared gun does not get fooled from bright surfaces and all measuring points will be a uniform color.
I lost my trans from parts failure and not from heat.
So my effort to keep it cool still did not prevent faulure so everyone must realize that pulling heavy loads involves more than just cooling.
The real facts are that some parts are not up to pulling the rated max loads on long term basis.
My trans shop which is LEVEL 10 built a pulling special using a diesel converter, high flow pump and other parts that are way heavey duty compared to Ford oem parts.
I wish you good luck and not be as much a pioneer as I had to be.
And by the way, the trans shifted perfect even as I drove it to the shop 70 miles one way, to be done over, so one would never know until the pan is dropped or total failure happens.

 

BG...

Thanks for the tips, as always. I will get the flat black paint out and paint the probed areas. I am also making sure to hit the metal lines and not the rubber portions.

I am trying to do all I can short of a total rebuild to extend the life of this transmission. I would say with 226,000 miles on the clock, I have gotten more life than a lot of folks, I know. Mainly...I don't want to be headed out to the woods with my wife and my camper, and then have a total transmission failure. I don't know if the bypass filter will help with debris collection, but it should keep the fluid cleaner, which can never hurt.

I am seriously considering the fluid switch to Mercon V as someone suggested. BUt like I stated earlier, my mechanic warns against it, and I do trust his opinion. He's one of those rare mechanics that people stumble across and you are lucky you do.

Thanks,
John