Transmission what is too hot
 

I have an E450 30' Class C motorhome and tow a vehicle. Combined weight is around 17,700. This is an 06 chassis with the 5R110 tranny. Using a scangauge since last fall. This is the first time I have been in warmer weather since getting the gauge. In the last few weeks have been towing in warmer ambient temps like 90's and 80's and have seen higher tranny temps. Prior to this warm weather I was generally in the 160's. Just the other day climbing a pass to 8,400 feet it got to 209. How hot is too hot for the good of the tranny? Jim

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209 is warm but not bad as I belive that the leaving the trans temp not the sump temp.
My trany guy say you realy want to know the sump temp cause if the sump / pan is over 190 your not going to pull enough heat out of the trans.

This was on my 96 f150 i was pulling a 8000lbs load most of the time my sump was 140 once i pulled 4 ton of stove pellets in the Enclosed trailer so i'm sure it was over 12000 in a f150 pan temp got to 185. This was with Royal purples Max ATF.

What ATF are you using?

209 is getting there.

If you plan on repeating the same route with the same load I would add an auxiliary cooler to the transmission.

Most of the good synthetic ATFs are rated for higher temperatures than some of the internals of your transmission. Where the temperature is taken is really important and I need to look at my tranny to see where the sending unit is.
On our Trophy truck (extreme example) we take the temperature on the output line and the pan. We had a situation where the pan temperature was fine but it was because of a restriction in the cooler so the fluid stayed in there longer and was cooled. Temps in the output line were skyrocketing and the converter cooked to the point it destroyed (burnt to pieces) a Wix racing filter that was inline, it literally was in pieces when I cut the filter open.
My point is it is important to know where in the system you're looking at the temps and I really wished the factories would give us the highest temperature rather than the pan temperature.

The transmission has 23,000 miles on it. I had it serviced at a Ford dealer just over two months ago. Two new filters, 10 quarts of fluid replaced Mercon LV. Jim

According to what I know from Mark 200F all day is fine..220 for a short period is ok too. But no more than 30 mins.

In reading other posts here I have seen references to Mark. Who is he?

Thanks to everyone for the feedback. If I were to do something about the cooler what type of business would I go to for that?

Jim

Just about everything you need to know about your tranny can be found here:

https://www.ford-trucks.com/forums/8...eshooting.html

Hi Jim... er, sorry... Mark, ;)
209 is warm, but not too hot. You are going to see slight variances depending on where your gauge sending unit is installed. ALso, being a van it is probably going to run a little hotter than a truck anyway. At 209 though, you are okay. Did you top off the oil yet? I am sure that it will go down some when you stick in the full ammount of fluid.

Not yet but will before we move again in a couple of days.