RooTBeeRthe1st
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Hahaha
That's one of those things I absolutely don't need any help with.
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Keeping coolant and transmission temps under control when towing in the summer heat
- Thread starter Geotrash
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That's one of those things I absolutely don't need any help with.
OP
OP
Update after test drive: Took the Yukon out for a little highway cruise to get it up to temperature this evening. Ambient air temp was 70ºF. The transmission temperature gradually climbed and held steady around 175º on the highway after 20 minutes or so. Then getting off the highway and going through traffic, the temp crept up to 185º. I stopped in a parking lot to check the cooler fan and it wasn't running yet. It didn't kick on until the indicated transmission temp was between 190º and 195ºF (stopped again to check when it was 194ºF), but it quickly stopped the rise and started bringing it back down. I shut the engine off and after a minute or so the fan stopped with the temp back down around 182ºF indicated.
Curious what those of you running this cooler are finding with it, where it keeps your temp with and without towing, and whether the fan brings your temp back down when towing up a grade effectively. Thanks for your thoughts.
Curious what those of you running this cooler are finding with it, where it keeps your temp with and without towing, and whether the fan brings your temp back down when towing up a grade effectively. Thanks for your thoughts.
thompsoj22
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Where did you tap power? Ign off fan off right? Those temps seem correct if you are still using the radiator "pre heater". How effective were you at getting the max ram air through the lower grill? The trans oil enters the bottom of the radiator "heater", Exit's the top "heated" and flows through the DERALE and back to the trans so temps will allways be influenced by radiator coolant. I have seen "stable" trans temps as low as 114 on 50 degree 70 mph freeway cruising, Which is "ram air" overcoming the radiator heater. My average temps on 80 degree oat are 155 degree's at 70 mph. Stop and go freeway traffic at 80 oat are same as yours approx 175 degrees once the fan comes on. Im going to eliminate the radiator from the circuit this summer and see how much of a difference it will make.
Just for the record: I kept the trans cooler circuit in the radiator.. So it goes
into the radiator - then to the derale cooler - then back to trans
In my short test drives, I'll get everything good and hot... Trans temp gets to
about 172* and stabilizes with suburban driving... IF I turn on the fan, the temp after a couple minutes will drop down to about 160* ish..
I haven't towed yet though... But I figure 10*-15* degree drop by turning on
the fan will keep me happy when towing
into the radiator - then to the derale cooler - then back to trans
In my short test drives, I'll get everything good and hot... Trans temp gets to
about 172* and stabilizes with suburban driving... IF I turn on the fan, the temp after a couple minutes will drop down to about 160* ish..
I haven't towed yet though... But I figure 10*-15* degree drop by turning on
the fan will keep me happy when towing
I highly recommend getting the fans programmed to come on with a higher duty cycle at lower temps. The factory programming is shit.
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thompsoj22
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Cant explain the "no power" fuel pump fuse location but given that the fan will run for just a few minutes after shutdown as you have explained in another post id give your install an A+! That looks profesional and will add reliability to your vehicle. As i have commented previously, In order to see the true capabilities of the DERALE i think it should be used as a standalone and not use the factory radiator heater. Another member has installed the same cooler without the radiator so we will know soon enough what the difference would be. Great work!
OP
OP
Thank you for the details on your numbers, John. I plumbed it so that coolant flows from the transmission directly to the Derale and then back to the transmission. I have a front license plate in the way of getting direct ram air on the cooler, so the next step will be to fabricate some deflectors from aluminum sheet to direct the ram air coming in on either side of the license plate through the cooler instead of beside it, and rivet them in place. The numbers I'm getting make sense to me though because the transmission temperature sensor sits in the valve body, so it's plausible that it would be 10-15º cooler by the time it gets to the thermal switch on the cooler's inlet port through 6' of mostly aluminum line. Thus, if the switch activates the fan at 180º it makes sense that at the valve body the temp would be 190º+ by the time the fan comes on.
I wired it into fuse #34 (S/Roof - Roof Beacon Relay (TRW), Sun- roof Module (CF5)) which is an 'always on' circuit typically used by police vehicles for the light bar, because I was in a hurry to get it tested and running (state inspection scheduled for this morning), but can easily put it in a different circuit. The fan will likely only run for a minute or two when cooling down anyway, but I would rather have it on a circuit that's switched on with the ignition. Problem is that every switched circuit I tried had no power unless its accompanying relay was also switched on. For example, the rear window defogger fuse wouldn't power up until I turned the rear defogger on. I have the up-fitters manual though so will figure out a better circuit.
One additional step I can take is to wire in an override switch that will allow me to turn the fan on before the temp gets to 194º indicated, or find a thermo switch that activates at 170º. I'll try these after I get the ram air directed toward the cooler better.
All of this said though, I like that this setup is running warmer than the Trucool 40K. With that cooler, I rarely saw transmission temps reach the minimum temp that GM specifies for continuous operation (150ºF). GM is very clear that it's possible to overcool a transmission with oil-to-air coolers, so as long as I can keep my trans temp above that and below 210ºF or so when towing on the hills or sitting in traffic, then I'll be fine with that.
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OP
OP
Thank you! Your ideas and photos helped tremendously - can't thank you enough for posting them.
OP
OP
Thanks for clarifying, Tom. I misread your photos. Sorry about that and thanks for clarifying and sharing your numbers. I like your idea of wiring in an override switch, and may do that.
OP
OP
That's a good idea and will likely do that, but I have a hunch that my engine cooling problem will be solved now that there isn't a massive transmission cooler in front of it. Time for an HP Tuners setup.
Oh I definitely agree that you helped it by relocating. Your factory settings on the tune will not allow a 97% duty cycle on the fans till your coolant is well into the upper 220 degree range. I need to do this upgrade to my Denali as well since we are doing a trip to Yellowstone this summer too.
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OP
OP
Sweet! Hope y'all have a fabulous trip!
I've towed a lightly loaded, single-axle 5x10 cargo trailer across Kansas from Virginia to CO and back twice - once in May and once in July. The OAT driving westbound in July was 102ºF in a hot spell and the engine and transmission were both getting warm. For our trip to Yellowstone this August, I want my cooling system upgraded and fully sorted before we set out, so that's why I'm doing this work now while I still have time to experiment.
Nice! When we moved to Texas from the Vail Valley in Colorado we pulled our Travel Trailer which was loaded to about 7500-8K#. I couldn’t keep the temps under control on the two mountain passes but once I got down on the plains it regulated great. Fast forward to last summer we borrowed our friends TT and went to Galveston. I had a hell of a time keeping the temps under 230 on both motor and Trans. That was even with a brand new radiator and cooling system flush. I am not risking it this time!!
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OP
OP
So tonight was a drive to soccer practice in 87° ambient temps. It took about 15 miles of driving to break 180° on the transmission temp, but then we sat in traffic for a while and the temperature crept up to 194°, before coming back down as the fan had turned on. Since the fan shut off temperature is 165° at the cooler inlet, it brought the transmission pan temperature down to about 178° before the fan shut off and the temperature started creeping back up again. Again, we will know more when we’re towing in the mountains this weekend, but I am very satisfied so far.
Also, when we parked at the game the fan was running, but shut off after maybe a minute, So having it wired into always on power doesn’t seem to be an issue so far.
Also, when we parked at the game the fan was running, but shut off after maybe a minute, So having it wired into always on power doesn’t seem to be an issue so far.
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kbuskill
***CAUTION*** I do my own stunts!
My main concern with it being hooked to constant power wouldn't be it running for too long after shutting the engine off.
My main concern would be a malfunction with the thermostatic switch getting stuck in the closed position allowing it to run continuously.
Odds are probably pretty slim but there is always that possibility. Having on a switched source would be a fail-safe just in case. It would suck to come out to a dead battery.
OP
OP
Yes, that’s my concern as well. That switch is not a real sturdy piece of kit either. I’ll definitely move it to a switched source.
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This is the correct fitting for the factory cooler. It's a 9/16 threaded end with a 3/8" quick disconnect.
https://www.napaonline.com/en/p/NDP7305088?impressionRank=1&vehicleAddPDP=true
https://www.napaonline.com/en/p/NDP7305088?impressionRank=1&vehicleAddPDP=true
OP
OP
Some more data for those of you following along and for those considering this path. Picked up the camper this morning with an ambient temp of around 70ºF. It's about a 10 mile drive to the storage place each way - most of it on I-95. On the way out, the transmission temp hovered around 175ºF on the highway and was up to 180º once I slowed down and was maneuvering around the lot. The Derale's fan didn't need to come on. After picking up the trailer, on the highway, my transmission temp hung around 185-190ºF, also likely below the fan threshold. Once I got off the highway though, the temperature quickly rose to 199ºF and peaked at 205ºF as I maneuvered around the neighborhood and arrived at the house, but quickly settled back down to 198ºF once I stopped and was idling in park for a minute.
Engine coolant temp never broke 200ºF in either direction. So far, this seems to be a win for engine cooling, and I'm cautiously optimistic that it'll be able to keep the transmission cool enough (below 215ºF on the hills) when towing in warmer weather - especially on the highway. More data to come this weekend.
Does this jibe with what you guys who also have the Derale see when towing?
Engine coolant temp never broke 200ºF in either direction. So far, this seems to be a win for engine cooling, and I'm cautiously optimistic that it'll be able to keep the transmission cool enough (below 215ºF on the hills) when towing in warmer weather - especially on the highway. More data to come this weekend.
Does this jibe with what you guys who also have the Derale see when towing?
OP
OP
Pulled the camper out to Charlottesville this weekend and learned some more along the way, and thought I’d share for others who may be planning some towing this summer. I’ve also done a bunch of reading - some of it in GM manuals, and talked to a few people, including the guy who runs the local transmission shop who put my torque converter in. All of it makes me less concerned than I was with transmission temperature.
My coolant temps are under control now. It was 70°F ambient on the outbound trip and the highest coolant temp I saw was 199°F. On the way home it was 85°F ambient and I saw my coolant get to 212°F a couple of times, but no higher. The Cold Case radiator is a beast, and getting that Trucool 40k out from in front of it was the ticket. I'm also glad I bypassed the radiator's transmission fluid heat exchanger when I installed the Derale, or I'd likely still be seeing higher coolant temps, though likely still well within the safe zone. That said, if you live in a colder climate, the pre-heat function of that circuit is important, and I would recommend leaving it in the loop to get the trans temp to the minimum 150ºF in cold weather.
My trans temp seems to be under control as well, though about 15°F higher than I’d like. On the outbound trip, it settled in at 197°F with a rare rise to 205° when maneuvering through small towns, or parking the trailer and such. On the return, it settled in around 203°F with a few rare rises to 212°F when pulling out of a rest area or driving in traffic after getting off the highway. But I noticed that the Derale fan seemed to do a great job of capping the rise and the temp would start to fall again after being in traffic for a few minutes.
My next steps are to get as much ram air into the Derale as I can, and monitor on some longer trips we have coming up.
Also, one of the things I’ve learned is that Dexron VI is much more resistant to high temperature oxidation, and that transmission temps up to 235°F are considered normal by GM for the 6L80E. Above 270°F the fluid will degrade rapidly, and I’m a long ways from that. I have some trips planned over the blue ridge in the next couple of months, but I’m not sweating them right now. I'll likely just plan to make transmission fluid changes an annual event after towing season.
My coolant temps are under control now. It was 70°F ambient on the outbound trip and the highest coolant temp I saw was 199°F. On the way home it was 85°F ambient and I saw my coolant get to 212°F a couple of times, but no higher. The Cold Case radiator is a beast, and getting that Trucool 40k out from in front of it was the ticket. I'm also glad I bypassed the radiator's transmission fluid heat exchanger when I installed the Derale, or I'd likely still be seeing higher coolant temps, though likely still well within the safe zone. That said, if you live in a colder climate, the pre-heat function of that circuit is important, and I would recommend leaving it in the loop to get the trans temp to the minimum 150ºF in cold weather.
My trans temp seems to be under control as well, though about 15°F higher than I’d like. On the outbound trip, it settled in at 197°F with a rare rise to 205° when maneuvering through small towns, or parking the trailer and such. On the return, it settled in around 203°F with a few rare rises to 212°F when pulling out of a rest area or driving in traffic after getting off the highway. But I noticed that the Derale fan seemed to do a great job of capping the rise and the temp would start to fall again after being in traffic for a few minutes.
My next steps are to get as much ram air into the Derale as I can, and monitor on some longer trips we have coming up.
Also, one of the things I’ve learned is that Dexron VI is much more resistant to high temperature oxidation, and that transmission temps up to 235°F are considered normal by GM for the 6L80E. Above 270°F the fluid will degrade rapidly, and I’m a long ways from that. I have some trips planned over the blue ridge in the next couple of months, but I’m not sweating them right now. I'll likely just plan to make transmission fluid changes an annual event after towing season.
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