Towing and temperature issues
- Thread starter lectric74
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thompsoj22
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ok so not trying to highjack but just got back from a trip to mammoth lakes ca. 190 miles from Ridgecrest ca at 2500 ft. to mammoth 8,000 ft. with an evil 14 mile 6% grade from bishop to crowley lake, avg temp 98f until you hit crowley lake than 78f. I have an 08 yukon denali xl 6.2 with 135,000 miles and tow an approx 4,750lb travel trailer. I recently changed the "holy grail of grills" out for the standard Silverado/tahoe grill with the lateral bars and there is no doubt about it that the "Denali holy grill" restricts ram air effect! seriously prior to installing the different grill the trans temp would not drop when decending a grade? my thought is that when decending and throttle off the coolant temp drops and turns off the electric fans and without suffecient ram air the trans cooler is stuck in "stale air"? with the new grill the trans never exceded 207 on the grade and averaged 175 on the flats. Stock trans cooler, is it possible that design engineers sacraficed performance for their perception of a luxury grill?
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Does everyone let their engine coolant rise to 220/240 when towing? At what point would you turn off the AC and open the windows?
My 2008 Explorer with the 6 speed kept the coolant below the 212, even going up the Grapevine in CA in August. I was quite impressed. My Tahoe would rise, but I don't have exact engine coolant temperatures. This was on the Coquihalla where you don't have ANYWHERE to pull over and people are coming up that hill at 80 mph easy. That would not be a fun place to break down. At least the Grapevine had some shoulder to pull over to.
My 2008 Explorer with the 6 speed kept the coolant below the 212, even going up the Grapevine in CA in August. I was quite impressed. My Tahoe would rise, but I don't have exact engine coolant temperatures. This was on the Coquihalla where you don't have ANYWHERE to pull over and people are coming up that hill at 80 mph easy. That would not be a fun place to break down. At least the Grapevine had some shoulder to pull over to.
swathdiver
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You'd think all the grills were flow tested, even the accessory ones.
thompsoj22
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im sure your correct, my guess is the volume is sufficient to supply air for the fans at all speeds but ram air speed/volume is diminished when the fans are off.
thompsoj22
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Also as i look at the photo i think ill miss the OEM look so i might get another emblem and run the original grill in the winter.
swathdiver
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Mine came with the black one, would be cool to light up GMC in red but that's a no no with the po po.
It was what really started this conversation. As for me, now that I know approximately what the temp is based on gauge position, I tend to turn the A/C off for a short time once it climbs to ~230, let the temp drop, then turn it back on. Usually the ECT drops quickly once the A/C stops, but fans stay steady. I'm hopeful that a good coolant flush will resolve these higher temps as the truck has 220k, and it may be about due for a water pump and thermostat. It might also benefit from a good flush through the radiator to help clean out all the bugs and debris that builds up and reduces flow.
As for the grill, I'm guessing the Holy Grail grill has the round holes as mine has more of an oval hole in the chrome grill. Either way, my emblem is gone as yours was and I'm honestly thinking the black grill looks better. May give that a shot to see how temps do, but I likely won't tow my trailer again until Sep when I bring it back down from my property. By then temps will below the steady 95-100 that I was towing in last weekend and this weekend. Temps seem to climb when towing steady, even across relatively flat land, at higher speed, while once I drop into town it will quickly drop to the normal range I see when not towing.
I managed to get a pic this weekend, not hooked up but gives a good idea.
swathdiver
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Nice! You might just want to replace the radiator with those miles on it. DO NOT get an aftermarket radiator as they do not have the built in restrictors that keep the temperature in check.
Transmission was 160 tonight on the way home, a little hotter than previously, but it was still 90 out and quite humid. Closest photo I took was last June, 92 degrees outside and 156 @ 76 MPH.
It was 99-100 for nearly the whole run south, hot!
It appears the trans isn't much to worry about, it never climbs above 220, and already has the heavy duty external cooler, but I may look at replacing all three, radiator, trans cooler and oil cooler, to help ensure longevity. Of course now I need to consider how long the engine may last having had AFM active all it's life. The list of maintenance items just keeps growing, but the wife loves the ride and comfort, and I don't miss all the manual shifting of the previous truck.
