First Trip Towing The Tt With The New Trans Cooler

rckt442 · July 7, 2008

I finally got to use the new Travel Trailer over the holiday weekend. The transmission cooler did its job. Towing the trailer home from the dealer, factory trans cooler, unloaded and no family in the truck, the temp hit 201 for a short time. On this trip, I had probably 1,000 lbs of cargo in the trailer and 250 lbs of family in the truck (wife and two small children) and took it 166 miles across mostly flat land. The hottest the transmission got to was 193 while climbing a small hill. Most of the time it ran 185-187. The temperature was about the same outside (90 F), so I think it was worth while to install the larger cooler.

Now for the bad news. The gas mileage sucked! I babied the throttle the whole trip and kept my speed at 60 mph and got a whopping 9.1 mpg. The trip was 80% interstate. I would hate to see what I would get driving this thing around in the city. Without the trailer I had been getting 18 mpg on the highway. So basically the mileage was cut in half towing the trailer. One thing I noticed is that while in tow/haul mode the converter never locks up, so I would bring it out of tow/haul in overdrive, after coming up to speed. Allowing the converter to lock up changed the instantaneous mileage from 7 to 10 mpg.

smattei14 · July 7, 2008

I finally got to use the new Travel Trailer over the holiday weekend. The transmission cooler did its job. Towing the trailer home from the dealer, factory trans cooler, unloaded and no family in the truck, the temp hit 201 for a short time. On this trip, I had probably 1,000 lbs of cargo in the trailer and 250 lbs of family in the truck (wife and two small children) and took it 166 miles across mostly flat land. The hottest the transmission got to was 193 while climbing a small hill. Most of the time it ran 185-187. The temperature was about the same outside (90 F), so I think it was worth while to install the larger cooler.

Now for the bad news. The gas mileage sucked! I babied the throttle the whole trip and kept my speed at 60 mph and got a whopping 9.1 mpg. The trip was 80% interstate. I would hate to see what I would get driving this thing around in the city. Without the trailer I had been getting 18 mpg on the highway. So basically the mileage was cut in half towing the trailer. One thing I noticed is that while in tow/haul mode the converter never locks up, so I would bring it out of tow/haul in overdrive, after coming up to speed. Allowing the converter to lock up changed the instantaneous mileage from 7 to 10 mpg.

That is great, your trans is cooler...I will be installing a new one soon too. I have a 2006 GMC Yukon Denali. This is the 1st weekend I was able to pull my 6000 lbs boat since getting the Denali 4 weeks ago. I would watch taking the truck out of T/H mode...

The shift points are longer and pressure is better for you trans when you are towing in T/H mode. On the flats if you have the just put it in "D" (keep the T/H mode on) and you will be fine. I got 11.3 mpg with a 6.0 Denali towing mostly up hill on a 85 degree day. I was even pushing it up some hills at times just to see how it could tow. On the flats are am around 65-70 MPH. There is one hill that is about a 3-4% slope (if not more...lets just say...there is a truck lane and the trucks are using their four ways sometimes if they are fully loaded) for about 3 miles and I was able to go up that hill in 3rd at 75 mph (should not have done that..but wanted to see how the engine and haul) not a problem and still got 11.3 mpg at the end of the trip...

It might be that I have the ele fans on the Denali, so the engine runs a bit hotter, so that could translate into better fuel econ.

Nice TT....Pilgram is a great Trailer!

Outbacker · July 7, 2008

Good to hear that the cooler workes for you. At the beginning of August I will towing for the first time with the new truck, so I will be watching the tranny temp and see how it does. BTW, your truck and trailer look great together. I wish that I saw more truck and trailer combo's that looked nice and level the way yours does. Saw one today and the trailer front was angled down and the truck front was angled up, and this was with a WDH. Not good.

Cheers.

slimjim2525 · July 7, 2008

I finally got to use the new Travel Trailer over the holiday weekend. The transmission cooler did its job. Towing the trailer home from the dealer, factory trans cooler, unloaded and no family in the truck, the temp hit 201 for a short time. On this trip, I had probably 1,000 lbs of cargo in the trailer and 250 lbs of family in the truck (wife and two small children) and took it 166 miles across mostly flat land. The hottest the transmission got to was 193 while climbing a small hill. Most of the time it ran 185-187. The temperature was about the same outside (90 F), so I think it was worth while to install the larger cooler.

Now for the bad news. The gas mileage sucked! I babied the throttle the whole trip and kept my speed at 60 mph and got a whopping 9.1 mpg. The trip was 80% interstate. I would hate to see what I would get driving this thing around in the city. Without the trailer I had been getting 18 mpg on the highway. So basically the mileage was cut in half towing the trailer. One thing I noticed is that while in tow/haul mode the converter never locks up, so I would bring it out of tow/haul in overdrive, after coming up to speed. Allowing the converter to lock up changed the instantaneous mileage from 7 to 10 mpg.

I don't understand why you would take it outof T/H mode? Just to get better gas mileage? It's a sure way to kill your tranny pulling something that large.

alaska511 · July 7, 2008

Good info!

Yes, I did the same cooler install and knocked 20*+ off my trans temps

I have been messing around with a few different combinations while towing my TT (6500 lbs) and this last weekend was the heaviest I have been.

My last trip a couple weeks ago, 440 miles WITHOUT the Nelson PCM/TCM and I averaged a miserable 8 mpg through mountainious terrain.

This trip (much more cargo, water on board etc) with the Nelson modules AND 91 octane, and I squeaked out 10.5 mpg!!!! Same terrain, kept it at 57-62 NEVER used cruise then entire time.

I think if I had some open interstate like you guys have down there, I could get 11.5...

I am pleased overall, and I will not run the stock modules ever again. As for the higher octane fuel, I will experiment further. I don't want to have to run that.

I am having Blackbear do a re-tune soon, so we will see what happens with that. I want my fans to come on at 205* when in tow/haul mode.

rckt442 · July 7, 2008

I finally got to use the new Travel Trailer over the holiday weekend. The transmission cooler did its job. Towing the trailer home from the dealer, factory trans cooler, unloaded and no family in the truck, the temp hit 201 for a short time. On this trip, I had probably 1,000 lbs of cargo in the trailer and 250 lbs of family in the truck (wife and two small children) and took it 166 miles across mostly flat land. The hottest the transmission got to was 193 while climbing a small hill. Most of the time it ran 185-187. The temperature was about the same outside (90 F), so I think it was worth while to install the larger cooler.

Now for the bad news. The gas mileage sucked! I babied the throttle the whole trip and kept my speed at 60 mph and got a whopping 9.1 mpg. The trip was 80% interstate. I would hate to see what I would get driving this thing around in the city. Without the trailer I had been getting 18 mpg on the highway. So basically the mileage was cut in half towing the trailer. One thing I noticed is that while in tow/haul mode the converter never locks up, so I would bring it out of tow/haul in overdrive, after coming up to speed. Allowing the converter to lock up changed the instantaneous mileage from 7 to 10 mpg.

I don't understand why you would take it outof T/H mode? Just to get better gas mileage? It's a sure way to kill your tranny pulling something that large.

Why would taking it out of T/H mode while running a constant speed hurt the tranny? The only thing I noticed is that it allowed the converter to lock up. It did not seem to affect the tranny temp at all.

jhbrennan · July 7, 2008

I finally got to use the new Travel Trailer over the holiday weekend. The transmission cooler did its job. Towing the trailer home from the dealer, factory trans cooler, unloaded and no family in the truck, the temp hit 201 for a short time. On this trip, I had probably 1,000 lbs of cargo in the trailer and 250 lbs of family in the truck (wife and two small children) and took it 166 miles across mostly flat land. The hottest the transmission got to was 193 while climbing a small hill. Most of the time it ran 185-187. The temperature was about the same outside (90 F), so I think it was worth while to install the larger cooler.

Now for the bad news. The gas mileage sucked! I babied the throttle the whole trip and kept my speed at 60 mph and got a whopping 9.1 mpg. The trip was 80% interstate. I would hate to see what I would get driving this thing around in the city. Without the trailer I had been getting 18 mpg on the highway. So basically the mileage was cut in half towing the trailer. One thing I noticed is that while in tow/haul mode the converter never locks up, so I would bring it out of tow/haul in overdrive, after coming up to speed. Allowing the converter to lock up changed the instantaneous mileage from 7 to 10 mpg.

That is great, your trans is cooler...I will be installing a new one soon too. I have a 2006 GMC Yukon Denali. This is the 1st weekend I was able to pull my 6000 lbs boat since getting the Denali 4 weeks ago. I would watch taking the truck out of T/H mode...

The shift points are longer and pressure is better for you trans when you are towing in T/H mode. On the flats if you have the just put it in "D" (keep the T/H mode on) and you will be fine. I got 11.3 mpg with a 6.0 Denali towing mostly up hill on a 85 degree day. I was even pushing it up some hills at times just to see how it could tow. On the flats are am around 65-70 MPH. There is one hill that is about a 3-4% slope (if not more...lets just say...there is a truck lane and the trucks are using their four ways sometimes if they are fully loaded) for about 3 miles and I was able to go up that hill in 3rd at 75 mph (should not have done that..but wanted to see how the engine and haul) not a problem and still got 11.3 mpg at the end of the trip...

It might be that I have the ele fans on the Denali, so the engine runs a bit hotter, so that could translate into better fuel econ.

Nice TT....Pilgram is a great Trailer!

My 2006 Yukon Denali had a transmission cooler as OEM - are you changing yours or by chance did your's not come with one?

rckt442 · July 7, 2008

My 2006 Yukon Denali had a transmission cooler as OEM - are you changing yours or by chance did your's not come with one?

24v · July 7, 2008

Why would taking it out of T/H mode while running a constant speed hurt the tranny? The only thing I noticed is that it allowed the converter to lock up. It did not seem to affect the tranny temp at all.

I'm not so sure the clutch in the converter can handle being locked with that kind of weight behind it. Just a guess.

50usilverado · July 8, 2008

how did you find the truck stability wis, what siza and type of tires do you have

smattei14 · July 8, 2008

I finally got to use the new Travel Trailer over the holiday weekend. The transmission cooler did its job. Towing the trailer home from the dealer, factory trans cooler, unloaded and no family in the truck, the temp hit 201 for a short time. On this trip, I had probably 1,000 lbs of cargo in the trailer and 250 lbs of family in the truck (wife and two small children) and took it 166 miles across mostly flat land. The hottest the transmission got to was 193 while climbing a small hill. Most of the time it ran 185-187. The temperature was about the same outside (90 F), so I think it was worth while to install the larger cooler.

Now for the bad news. The gas mileage sucked! I babied the throttle the whole trip and kept my speed at 60 mph and got a whopping 9.1 mpg. The trip was 80% interstate. I would hate to see what I would get driving this thing around in the city. Without the trailer I had been getting 18 mpg on the highway. So basically the mileage was cut in half towing the trailer. One thing I noticed is that while in tow/haul mode the converter never locks up, so I would bring it out of tow/haul in overdrive, after coming up to speed. Allowing the converter to lock up changed the instantaneous mileage from 7 to 10 mpg.

That is great, your trans is cooler...I will be installing a new one soon too. I have a 2006 GMC Yukon Denali. This is the 1st weekend I was able to pull my 6000 lbs boat since getting the Denali 4 weeks ago. I would watch taking the truck out of T/H mode...

The shift points are longer and pressure is better for you trans when you are towing in T/H mode. On the flats if you have the just put it in "D" (keep the T/H mode on) and you will be fine. I got 11.3 mpg with a 6.0 Denali towing mostly up hill on a 85 degree day. I was even pushing it up some hills at times just to see how it could tow. On the flats are am around 65-70 MPH. There is one hill that is about a 3-4% slope (if not more...lets just say...there is a truck lane and the trucks are using their four ways sometimes if they are fully loaded) for about 3 miles and I was able to go up that hill in 3rd at 75 mph (should not have done that..but wanted to see how the engine and haul) not a problem and still got 11.3 mpg at the end of the trip...

It might be that I have the ele fans on the Denali, so the engine runs a bit hotter, so that could translate into better fuel econ.

Nice TT....Pilgram is a great Trailer!

My 2006 Yukon Denali had a transmission cooler as OEM - are you changing yours or by chance did your's not come with one?

Mine came with a trans cooler...I just want to upgrade it because its too small...the temp is way to high for my liking....

Does it come with oil cooler? If not I might put that on when I put on the new trans cooler.

C & A s Dad · July 8, 2008

I finally got to use the new Travel Trailer over the holiday weekend. The transmission cooler did its job. Towing the trailer home from the dealer, factory trans cooler, unloaded and no family in the truck, the temp hit 201 for a short time. On this trip, I had probably 1,000 lbs of cargo in the trailer and 250 lbs of family in the truck (wife and two small children) and took it 166 miles across mostly flat land. The hottest the transmission got to was 193 while climbing a small hill. Most of the time it ran 185-187. The temperature was about the same outside (90 F), so I think it was worth while to install the larger cooler.

Now for the bad news. The gas mileage sucked! I babied the throttle the whole trip and kept my speed at 60 mph and got a whopping 9.1 mpg. The trip was 80% interstate. I would hate to see what I would get driving this thing around in the city. Without the trailer I had been getting 18 mpg on the highway. So basically the mileage was cut in half towing the trailer. One thing I noticed is that while in tow/haul mode the converter never locks up, so I would bring it out of tow/haul in overdrive, after coming up to speed. Allowing the converter to lock up changed the instantaneous mileage from 7 to 10 mpg.

Todd,

I am happy to see the cooler upgrade kept your temps under 200. The next time you tow, leave it in 3rd with the T/H mode engaged and see what your temps run. If you are towing on a 2 lane road around 50 to 60 MPH I think you will find you like 3rd and my bet is your trans temps will be even lower. Each time the trans shift up or down or the converter locks or unlocks, heat is generated. Not that your temps are too high, but you may want to try 3rd with the T/H mode.

As far as the MPG while towing, I will pass along something I have heard my Dad say a hundred times:

"If you are gonna dance, you gotta pay the fiddler".

BTW, your truck and camper do make a nice looking rig. Nice a level as they should be.