Well I thought I'd share my findings on trans temps delivering hay lately. Been hauling the same size load on same road, made four trips over the last month or so for this example. Most of my other deliveries are closer to home and trans never gets warmed all the way up. Trailer is weighing in roughly at 15,000 and making a 70 mile each way trip at 55-60 mph.  Takes a little over half way through the trip to reach its towing temp of about 190°. Running empty I usually see 150-160°. Temp probe is in drivers side pto cover, I installed it when I changed trans fluid to amsoil in the spring. I did however take the expressway home today because I was running short on time and had to get to work and was surprised to actually see temps around 200-210° with just empty trailer running 70mph. Just sharing some of my experiences and wondering what some others might be seeing. I would like to try a fast cooler in the future and see if there's any temp drop but for this summer probably will stay stock. 

 

Sorry the pic isn't the best but you get the idea. 

My nv5600 on hot days in 90s will get up to 175-180 empty on hwy going 70-75. I have one fast cooler on driver side and gravity filter (qk100) on passenger side. I want to run fast cooler with their filter on passenger side but it won't clear my 5" exhaust. I haven't towed in a while but my little 17' boat maybe 3k total and temps with that are not much higher right around 180

Now on my last pull towing the RV home using 245's tires I kept my transmission temperature down to the 160-170*F realm. No fast coolers and only using 50 SAE gear lube. My typical high is about 190*F towing trailers and running highway speeds trailers can range from a 7x12 filled with heavy firewood to 31 foot Jayco RV but pulling on mountain roads with grades up to 7% typically. Normal average is 140-160*F empty run on a 100-110*F outside temperature.

 

Another thing I've learned is the fluid is hotter on top (where the heat rises to) than at the bottom. So don't use the probe hole of the fast coolers. This gives a false cooler reading because it's so far from the gear teeth which is where the heat is generated in the gearbox. Like I've got mine on the passenger side fill hole with about a pint extra fluid in to keep the sensor submerged. Being the exhaust side of the case is the hottest and the top is where the heat rises too. 

Edited July 29, 20186 yr by Mopar1973Man

9 hours ago, Dieselfuture said:

Have you changed that filter out yet? I have seen them before, looks like a good idea. Obviously not going to remove foreign material like a pressurized system but anything taken out of the oil is better than nothing imo. 

 

@Mopar1973Man I am running stock 235's. We definitely don't have the hills you do here in Michigan. 

 

Why I don't like the fast coolers. If you look the probe is at the bottom of the case and farthest possible distance away from the gears where the heat is. The probe needs to be at the top of the oil where heat rises too and close as possible to the gears for accuracy.

Edited July 30, 20186 yr by Mopar1973Man

Would be nicer if it was up a little higher. I would be curious what the temp difference is. 

I know from measuring from the fill hole at the very edge to the gear teeth could rise almost another 20-30 degrees. Much hotter near the gears than at the case edge. Now with a fast cooler on the side and farther away will make it inherently cooler temperature.  

58 minutes ago, Dmaney said:

Have you changed that filter out yet?

Not yet but think I might sooner than later. 

 

40 minutes ago, Mopar1973Man said:

Why I don't like the fast coolers. If you look the probe is at the bottom of the case and farthest possible distance away from the gears where the heat is

I could flip it over then it be closer to gears and on top but I wasn't sure how much it would be in oil when driving. Next time I drain it and chance filter I might flip it an see.

My oil level is to bottom of top side pto bolt hole and that's 3qt overfilled, when driving some of it is flying around. Idk..

That's right darn 6 speed... 

 

22 minutes ago, Mopar1973Man said:

That's right darn 6 speed... 

 

Nothing wrong with 6 speeds!  I actually miss my old ones, I prefer towing with them but this 5 speed is what was in the "right" truck so I'll run it. Still way better than the slushbox. Actually just driving empty its definitely nice and cheaper to repair so just make the best of it. 

I was referring to the goofy level of oil they hold. Seems like it so low on the case. Where the 5 speed seems to have oil all the way up to the top on a normal fill. 

30 minutes ago, Mopar1973Man said:

I was referring to the goofy level of oil they hold. Seems like it so low on the case. Where the 5 speed seems to have oil all the way up to the top on a normal fill. 

I'm picking up what your droppin. That was probably another win for the bean counters. 

58 minutes ago, Dmaney said:

I'm picking up what your droppin. That was probably another win for the bean counters. 

 

Explains why the 6 speed needs to be overfilled and the 5 speed doesn't have that issue with bearing lubrication. Putting the pieces together.  

I know running 8 quarts if you take shifter tower off and look inside you still have to look to find oil, no wonder they have bearing failure with running 5 quarts

Funny NV4500 only needs 4 quarts and the main shaft is swimming in gear oil.

I have Fastcoolers on my 4500 and overfilled with about 7 quarts of OEM SyntorqLT.  My empty driving temps will generally run in the 120-170* range depending on the ambient temperature and how fast I'm driving.  Remember, running in OD (5th gear) will always build more heat simply because of the ratio reduction.  You cant get away from that.  But driving in 1:1 (4th gear) will result in the coolest temps possible since power runs straight through in and out and very little heat is generated.

 

Towing my 5th wheel the transmission will run in the 150-185* range depending on the ambient temperature.  But if I have to pull and long grades in 3rd gear then the temperature can climb, eventually reaching 200-210* if I hold that gear long enough and its hot enough outside.  That said... I do NOT tow in 5th gear unless its something lightweight like a rowboat or small trailer.  The heat placed on the 5th gear is too great and the stress on the engine and drivetrain is obvious.  I'm in no hurry so...

 

As for the temperature readings and where the sensor is located, I've confirmed with a laser temp tool that the iron transmission housing is the same temperature as what the gauge is reading, as is the aluminum Fastcooler.  That tells me that the fluid is moving about and mixing at too fast of a pace for there to be any significant temperature differences from whatever level the sensor is located.  The ONLY place the oil could be hotter is in the small areas between the gears and bearings under the most load...but that something you'll never be able to monitor.  Simply taking the overall temperature as a running condition average based on load is all you can do.

 

Lastly, what I also discovered when first monitoring my transmission temperatures years ago was the fact that the hot neighboring 900*+ exhaust pipe on long hot pulls can and will heat up the transmission fluid temperature merely through radiant heat transfer.  So I blanketed the exhaust (not wrapped) with 6 feet of blanketing and the temperature interference is no longer a problem.

 

Here's some pictures of what I did and what it looks like.

 

 

I've towed somewhat heavy in 6th (13-14k)before I read up on this temp thing now if I tow that heavy I'm only in 6th on hwy going 65-70 any Hill I drop to 5th and slow down a bit. Truck had no problems pulling in 6th but after reading some horror stories and not just about tranny, some had issues melting pistons I guess, I don't take chances. My boat at about 3k I still pull in 6th unless it's a steeper hill.

@KATOOM how heavy is your 5th wheel? I like your fast cooler setup and heat blankets, looks just like some of the stuff covering some of the steam piping at work. 

All I got to say is before anyone dives off the deep end here I would highly suggest first installing a transmission temperature gauge first and see what your transmission is actually running for temperatures. Since I've installed my gauge there has only been one time I've ever trip my high limit light at 220*F that was to study gear usage and speed. After learning proper gear usage I've really struggle to exceed 160*F. Again I've got no heat shields, no exhaust pipe wrap, no fast coolers. 

 

The other factor is proper sized tires as I found out 245's (30-inch) vs 235's (31-inch)  run much cooler transmission temperatures. Final gear ratio to the ground closer to 3.73 will reduce transmission temperature greatly. This just goes to show how inefficient larger oversized tires are and how they trap the torque in the driveline and create un-necessary heat. 

4 hours ago, Dmaney said:

@KATOOM how heavy is your 5th wheel? I like your fast cooler setup and heat blankets, looks just like some of the stuff covering some of the steam piping at work. 

 

14k - 15k toy hauler, depending on how much I have packed in it and whats in the tanks.

 

I agree with Moparman in that anyone concerned should invest in a temperature gauge just to understand whats happening at all times.  But that said, if you tow only in 4th gear you'll never have a heat problem.