Every transmission temp thread seems to be about hi temps (for obvious reasons). But I am wondering what would be considered a normal "lower end" temp. Im in Alaska so not dealing with extreme air temps. But I do pull loads up hills for hundreds of miles. I just put an additional small cooler on and a temp sensor and gauge at the same time. I should have installed the gauge first to see if the extra cooler has any effect. But its springtime in Alaska and Im too busy to tinker.

I did a trip pulling 3500 lb trailer up some pretty steep grades and the new gauge barely registered anything over 140-150. I expected some needle movement on the hills but only got about the width of the needle.

Has me thinkiing the gauge is faulty or the probe is installed in the wrong place. I put the probe into a plugged hole on the driver's side of the transmission just above the pan. A little bit of fluid ran out so I know it is exposed to the fluid.

For reference....air temps were 45F-65F. And the truck now has the radiator cooler, the stock air cooler and the additional 11"x11" stacked plate cooler that I just put in. I run full synthetic fluid (freshly changed) and a magnafine filter inline. Even my old fluid was ruby red. is 140F-150F what I should be seeing? Or do I have an indication problem?

If Im actually cooling it to 140F, Im thinking I will probably have to cover or bypass the extra cooler in the winter when our air temps are below zero F.

 

I tug a 10k travel trailer in teh PSD Ex, equipped with a 6L trans oil cooler. My OBD-derived temps are typically 145-155 max on the flats, even in summertime.

Makes me smile, as they were blowing over 200-210 with the stock cooler (and puking out when backing up).

I'm not aware there's a downside to having cold trans temps.

 

Mine runs cool too unless I'm really heavy and climbing hills and I always wondered if lack of heat might be a problem as well. The only thing I can think of would be if moisture was in there, it might not be getting warm enough to cook it out.

 

Mark, I see you're a Skyhawk driver. I owned a Grumman Tiger for some damn near 20 years. They (A&Ps) told us we needed to get the airplane engine oil hot and let it run hot - 180F or more - to "boil off" condensation. And that makes sense, and I followed the advice by ensuring that when I flew it, I planned on doing it for more than a short time..

But I also thought of it this way. We don't need to "boil off" water - for example, get the oil temps to 212 degrees. No, water will evaporate just fine at lower temperatures, even room temperatures, it just takes longer. So while we may not get our truck's trans oil temps to 180 or more degrees, by driving it a longer reasonable amount of time - e.g., not driving the truck to the corner store 20 times a week during the winter - any water should evaporate out just fine.

Further, since I tow most of this truck's use, I do like to flush out the fluid every 25k miles or so. Maybe that's excessive for a trans that runs at 150F or so, but it makes me feel better.

 

The 4R100 trans normally runs about 160-120°F above ambient temperature. You have a pretty light load, and additional cooling. So running right around 100°F above ambient is right about what I would expect.

That is the pressure test port. It is a good place to put the probe.

When I lived in Michigan I covered my coolers with cardboard in the winter. You should cover yours when it's cold.

Oh, there are. When the trans is cold it is less efficient and you'll get lower fuel economy. If it is too cold it won't force out moisture that can collect in a transmission. And worse of all, if the ATF stays REALLY cold for a long time it can get really thick and won't flow properly. This can cause a lack of lube and a transmission failure.

 

A bit more detail about my old kidney twisting f350 - it started life as what we call a "slope truck" up in the oil fields of Prudhoe Bay Alaska. its a 2000 model with only 126k miles. But Ive heard they idle them for days and weeks at a time up there. I dont think this one was up there too long tho. Ive had it 5 yrs and has never failed to start as long as I give it a fresh oil change in the Fall and a few hrs plugged in if its below about 15F. She smokes like a dumpster fire when cold starting but always starts and it clears up after a few mins. My biggest complaint is the eng is loud as hell and the ride is like a pioneer wagon unless it had a thousand pounds in he bed. Not a luxury ride but a great homestead truck that gets the job done. I get the feeling the tranny is the weak link so thats my biggest concern.

 

@Grape Nehi , Mark Kovalsky is the transmission expert in here and it is based on remarks of his like the one above that I installed a transmission Fluid Control Thermostat.
https://smile.amazon.com/dp/B004XOQ0...GHKPYDBXFGR0YE

 

I have a similar setup.
New trans with synthetic fluid.
ALOT OF SYNTHETIC FLUID!
Magtec extra deep trans. Pan.
External trans filter.
Large new trans cooler
New lines
New radiator
Isspro trans gauge tapped into passenger side of oil pan which is aluminum and ribbed at bottom of pan.
I barely see 120 at ambient Temps of 65.
Gauge starts at 100 and in the winter barely goes up at all unless I drive for hours.
In summer it goes up to140-150 w/o a load on hottest days in heavy traffic and hills.

 

I want to hear more about the homestead.

I actually lost a cylinder in my Skyhawk to that moisture thing. I flew back from NY in cold temps without any of my winter guards on and then it sat for a couple of months in the hangar. I don't understand why but only one cylinder rusted up and had to be replaced. It might have been the only one with valves open. I suspect that even if the hot places get warm enough to drive out moisture, there are remote places that still don't get warm enough and moisture hangs there, then drives up humidity and circulates around.

 

I thought you meant one of these when I first read that.


I used to be a flight test engineer on projects involving these things.

 

So then what's our bogey numbers? Where do we want to be?
I hear you. But I suggest in that situation it was the "months" and inactivity that killed you, not the temperature. I did everything I could to not let mine sit for more than a week, even offering to let friends fly it for free. And it was because of my inability to keep it regularly flying that I finally had to let it go. But when I was flying 125-150 hours per year I didn't have to top overhaul it until 1500SMOH and the engine went over 2500 before I finally felt paranoid enough to just rebuilt it.

As with our brake calipers (for example) mechanical stuff just doesn't like sitting around unused.
Wicked. It would be one I'd buy if I had FU money (assuming the Navy would release them.)

 

If memory serves, Mark has previously mentioned 180.

Ask and ye shall receive.
https://www.controller.com/listing/f...itary-aircraft

 

Very cool! Now to work on that "FU money" part...

(My Tiger - not an F11F, sadly - had wingtip LED strobes as well as a very bright Xenon nose light. Occsionally I'd call in on a long approach on clear night as "Grumman 140" and get a 5-mile clear to land, with a request to pick up the pace...I'd reply "um, I'm doing 135 knots and that's ***** to the wall"...I guess thy thought I was a corporate jet...)

 

I understand what you are saying but I beg to differ, at least on this issue. There seem to be quite a few specimens around that sit for years and even decades in these hangars that are fine when they are traded and put back into active service. I do pull the prop through every time I go down there though.

It looks like someone has poached a trademark name. I was unaware that there was a military Skyhawk and thought that might be a Falcon when I saw that picture of it (my knowledge on those things is really, really poor).

 

So you're a rocket scientist, eh? I thought you looked really smart.