I was towing a 2009 33.6' fifth wheel, with a trailer max weight of 12,500lbs.

I live in Washington and even long the I-5 we have some pretty decent hills.

I drive about 65-70 mph on the flats and about 60-65 mph on the hills.
I was watching the tranny temp gauge while I'm towing and it would see as high as 220. That's with the Spartan Heavy Tow with the tow/haul on. Maybe I'm going too fast?

Is that normal? Because I'm thinking of adding an additional tranny cooler with a fan that I can turn on if the temps get too high.

Also when I first started to pull the trailer, had it in tow/haul. But when I pulled over for lunch, I forgot to push in the tow/haul mode. Then I came to a hill and the temp started to climb, it reached 240 before I realized it. It was for 2-3 minutes max. Then I turn on the tow/haul when I realized it wasn't on. The temp went down pretty fast after that.

Do you think that the tranny's ok or do I need to flush the tranny fluid?

Also I have the Mag-Hytec tranny pan which adds another 9 more quarts to the stock level.

Thanks in advance.

 

IMO (to be safe) - Over 220 is too hot for continuous service. Never exceed 240 for more than 30 minutes.

Mark Kovalsky (former Ford Tranny engineer) says the fluid can get to temps in the range of 250 for a SHORT time w/o any damage. The tow/haul light will flash at 275. The gage moves to red at 280. This is supported on page 36 of the OBDII Theory and Operations manual.

Sounds like you should be fine. It is good you are watching it closely.

I did flush mine at 30k. Opinions are very diverse on the flushing part. You definitely should change the fluid at 30k if you haven't already.

I do not think you need an extra fan.

ps - you have a pm.

 

I agree with Bismic and want to add that I hope you are changing the external trans filter at 15,000 mile intervals or 10,000 mile intervals if you are doing alot of towing. 15,000 according to manual, 10,000 according to me. JMHO

 

Wow, 220* with a Mag Hytec pan ?

 

Hey guys thanks for the quick reply.

I had the tranny flushed and service not that long ago(about 8,000 miles ago). This is why I'm kinda of dumb founded. I think that I'll change that external filter to be on the safe side.

I was kind of surprised that the tranny reached 220 even with the Mag-hytec pan. Maybe I trying to push it too hard? But on the flats, it does awesome with power to spare.

I heard that it's not good to keep the tranny too cool. Not sure where I heard that, but that's I was looking at a second cooler with a fan to better control the temp if needed.

Hey bismic, I sent you an email, thanks again.

 

A bigger pan doesn't help cooling the trans. It will take a bit longer to get it hot, but it will get hot. 220°F isn't going to hurt it. Either will 240°F for a short time.

If you do add more cooling, make sure that it's a stacked plate cooler with AT LEAST 1/2" passages and lines. You don't want to restrict the cooler flow.

 

A bigger pan does aide in keeping the transmission cooler. It allows more fluid to be cycled which takes longer to heat all the fluid, but the Mag Hytec also has some fins on it to aide in cooling. (May be minimal but it's something.) Is it better than a bigger or 2nd cooler, no but it does help.

 

I added an aftermarket trans filter, I think from Dieselsite. My trans gauge reads about 5 degrees cooler around town, went from 160 to 155 or so. Not sure why that happened, I thought the trans had a thermostat?

 

There are some dealerships that do not change the external filter when doing a flush unless specifically asked to do so. Doesn't make sense but it's fact.

 

That's nothing more than wishful thinking, with an unhealthy dose of marketing thrown in.

There is very little fluid flow near the inside surface of the pan. I've done engineering tests that showed this. With very little flow against the surface of the pan there can be very little heat transfer. And that's a good thing, because you don't want the fluid any hotter than it already is.

The pan is in an area that is HOT. Ever stand next to a running truck on a hot day? Do you feel cool air or hot air coming out from under the truck? It's always been hot in my experience, and my measurements, too.

The air around the trans, where the pan is located, sees hot air that is dumped from under the hood, plus air that is heated by the exhaust. The air around the trans is usually 200+°F. How is a pan, even with cooling fins, going to cool the trans fluid when the air around it is at least 200°F? It's not possible.

If you want to cool the trans, work on getting the hot fluid to a place that has cool air. The space in front of the radiator has cool air, maybe that's why the coolers are there, not under the truck where it's hot.

 

After installing a Mag-Hytec pan on mine I've seen no difference on the ISSPRO trans gauge while towing up the Grapevine grade.
Anybody want to buy a Mag-Hytec pan in great condition?

I've seen a slight lowering of temps after installing a Dieselsite remote trans filter outside of the frame rail on the passenger side, though my measurements are not scientific and may just be wishful thinking. I installed it for the extra filtration with no expectation of any temperature differences.

I've never seen the trans temp on mine above 220, and only touched 220 on a 100+ August day towing 30 to 50 mph up a steep, winding side road bypassing the Grapevine.

 

Thanks Mark Kovalsky for the information about the temps. With a larger pan, will it take longer for the tranny fluid to break down because of the higher heat or will the time be the same?

69CJ, first off, I'm jealous about your 1969 CJ Mustang (I have a 1967 Mustang with AC and bench seat in the front.) Thanks for the heads up on the exterior filter may not be changed thing. I'm going to call them for sure now. That's part of the tranny filtering and cooling system, I thought..........

Will running a tow tune make the tranny hotter? How about a stock tune?

Kepler4, are you running a tune or stock? I know the grapevine very well. I used to drive long haul with the big rigs over that pass. It pretty nasty on a hot day.

Sorry about all the questions, but it's not everyday that you can ask many people with the alot of knowledge about our trucks from all over.............................. Except here

 

My truck is stock but from what I have learned here and on other sites, SCT is the best tuner for both the engine and trans. People claim thet the edge is esp. hard on the trans and Banks is overpriced.

 

I've run it both stock and with SCT tow tunes pulling my 12.5K trailer. My truck has never had overheating issues either way, trans or engine. I think a lot of overheating issues are related to the drivers right foot, unless the vehicle is mechanically unsound.

I can accelerate up the Grapevine pulling my trailer but the engine temp, trans temp, and EGT rise rapidly. There's really no reason to punish the drivetrain by doing so since time can be made up on the flats in the San Joaquin Valley. I betcha remember doing that!

 

I haven't studied that, but I can give you what I think will happen.

The fluid will take longer to heat up because there is more of it, but also it will take longer to cool off because there is more of it. So the time at temperature is about the same, so the fluid breakdown from heat will be about the same.