transmission cooler

[hhoenig]

our tv is an 05 GMC Envoy 8 cyl 7 passenger. comes equipped with hitch receiver and all needed wiring. we (wife and 2 kids) are towing a 2619 with air, awning, etc.There is no transmission cooler, do we need one? Tow capacity as is, is 6700 lbs. We will be travelling NY, PA, MA. Don't want any breakdowns nor do I want to void the warranty. Any feedback would be appreciated.
Henry

With your set up you nor your SUV will be able to tell the trailer is back there. You should however keep checking your rearview mirror just in case you run off and leave it somewhere.

Henry
I have a 4 Liter inline 6 Envoy and pull a 3026 King with it. Hardly know its back there except I use 3rd gear rather than 4th/OD. It pulls the TM like a dream. In Az, my temperature guage only moves up slightly on the toughest climbs. Without traffic in the way, I can hold 50 MPH on all the hills with maybe half throttle in 2nd. That's about 3500 to 4000 RPM. I can't tell you about tranny temp, though. I am considering installing a tranny temp guage.
Bob

I agree, you will be prefectly fine. When I got mine I had the same concerns. I have the 6 Cyl. and feel it is matched quite well with our 2720SL. Though sometimes I have thought of installing a Transmission Temp gauge just to see what the temp may be.

[RockyMtnRay]

Originally Posted by hhoenig

our tv is an 05 GMC Envoy 8 cyl 7 passenger. comes equipped with hitch receiver and all needed wiring. we (wife and 2 kids) are towing a 2619 with air, awning, etc.There is no transmission cooler, do we need one? Tow capacity as is, is 6700 lbs. We will be travelling NY, PA, MA. Don't want any breakdowns nor do I want to void the warranty. Any feedback would be appreciated.
Henry

Actually you do have a tranny cooler...it's built into the bottom of the radiator. Whether or not you need an external (auxiliary) cooler is a good question. I do have an external (factory) cooler on my truck...and I also installed a transmission temperature gauge so I could monitor transmission temperatures because I do severe mountain towing on just about every trip. Based on the temperature rises I've seen while climbing long/steep mountain grades with my 2720SL in tow (but just me in the truck), I'm very happy I have an external cooler and have even given thought to replacing it with a higher capacity aftermarket cooler.

If you always stay on flat roads and never tow up long and steep grades...like they have in West Virginia and some mountainous areas of Pennsylvania, then you probably don't need to have a transmission cooler installed. However if you foresee doing that kind of towing even once in a while, then an external cooler is definitely a good idea. They're not expensive (good ones sell for under $100) and generally easy to install (under an hour of time with normal tools). The most recent issue of Trailer Life magazine has two good articles on the need and "how to" of installing an aftermarket transmission cooler.

I might add that the coolant temperature gauge is a very poor...and possibly an exceedingly misleading indicator of what's happening to transmission fluid temperatures. My truck seems to have a very effective radiator because I've never seen the coolant temperature rise above normal even on very long/steep climbs in hot weather (though the radiator fan clutch did engage). By comparison, the transmission fluid temperature rose from 165 to 195 degrees in just 7 miles of towing up a 5 to 6 percent grade...and 195 degrees is about the highest "safe" transmission fluid temperature according to the GM engineers quoted in the TL article.

So, being one of the very few folks (if not the only person) on this forum who has observed my tow vehicle's actual transmisson temperature over thousands of miles of towing, I'd suggest that for peace of mind if nothing else...and considering the relatively low cost and ease of installation, you would be prudent to install (or have installed) an external transmission cooler.