Community Forums

wheels · 11-30-2012, 10:04 AM

I have a 2003 Chev Silverado 5.3 with a tow package & OEM cooler. I've been looking at putting on another - add-on - cooler for warmer climates. Wondering what thoughts are out there about doing this. I tow a 19 foot bumper pull. When towing in a warmer climate we've experienced a temperature rise in the transmission. I live in No. Wisconsin where it gets below zero at times and am wondering what effect putting on an additional cooler would have - could I just let it warm up before driving it during colder times - would that take care of that? Are there any recommendations on what kind of cooler and where to purchase one? Thanks in advance for any & all advice!

chief02 · 11-30-2012, 10:14 AM

Automatic trannies are the weakest links when towing and heat build up will destroy it. A good trans shop can advise you on a good after market cooler. As far as trannie warm up, they really dont warm up much till you drive them. I let my engine warm up then go for a trip around the block before I hitch up and tow.

Shadowcatche · 11-30-2012, 10:41 AM

I am towing a large teardrop trailer with a Subaru Outback and I added the biggest transmission cooler I could find that would fit and switched to synthetic ATF. There is a temperature operated vale that allows flow tot eh cooler when it is hot. In reality it is hard to be too cold for ATF.

tuffr2 · 12-07-2012, 04:46 PM

Add on transmission coolers do work. Here is my experience. In the mid 80's I towed a 17' I/O boat with a V8 powered Ford car. Car rated to tow 2,000 lbs. Boat, trailer, motor weighed 2,700 lbs. I towed approx. 30,000 miles. The car had a big black mark for transmission in the Consumer Reports. Lots of trouble with transmissions. I put 151,000 miles on the car when I traded it. Never had a transmission issue. I attribute it to the trans cooler I added before towing.

Arch Hoagland · 12-07-2012, 05:50 PM

wheels....I'm curious how you know your transmission is heating up.

I had that same truck and there was no transmission temp gauge.

For what's it worth I pulled a 22h Nash travel trailer over over the west in extremely hot weather and never had a problem with transmission.

wheels · 12-07-2012, 08:34 PM

Arch - I put an add on temperature sending unit & temperature guage in my truck. The sending unit goes in one of the transmission cooling lines. I also ordered a transmission cooler from etrailer.com. It was a good experience ordering from them. I installed the cooler - it went quite well. Just to be on the safe side & hopefully it'll just be an insurance policy. Thanks to all who have responded to my question(s). ~Wheels

Arch Hoagland · 12-07-2012, 11:28 PM

I later bought a 2004 3/4 ton GMC with the 8.1 and Allison 1000. I pulled a 27' Komfort travel trailer with it.

It had a transmission temp gauge and I noticed it heated up the most in stop and go traffic.

Climbing mountains didn't seem to heat it up.

What has been your experience with heating in various driving conditions?

SmokeyWren · 12-08-2012, 08:41 AM

I wouldn't want to tow more than a rowboat without a tranny temp gauge. The red line is 225° F. "sump temp", or the temp of the ATF in the pan. If you ever see more than 225°, you need more ATF cooling capacity.

The way to get sump temp is to drill a hole the tranny pan, and weld in a threaded bung sized to fit the sender. Some trannies may already have a threaded location where you can get sump temp. For example, the '99-'03 Ford 7.3L engine with 4R100 tranny has a "test port" on the driver's side of the tranny where you can get almost exactly the sump temp. So almost all of the guys with those trucks installed the tranny temp sender in that location.

The tranny cooler lines are awful places to get tranny temp. The "hot" line can scare you to death with temps well over 300° with no cause for alarm. That's the temp of the ATF coming out of the torque converter, and it's often a lot hotter than tranny temp - especially if the torque converter is unlocked and working hard. The cooler return line tells you the temp of the ATF coming back from the coolers, and that temp should be a lot less than tranny temp. On my '99.5 7.3L Ford, I had a gauge for sump temp, but just for grins I also had cooler return line temp. The cooler return line temp was usually 30° to 50° cooler than the sump temp.

If you add ATF cooling capacity via a bigger oil-to-air (OTA) heat exchanger, double-check that you still have adequate ATF flow after the cooler is installed and the ATF level is checked and everything is buttoned up. "Adequate" flow is one GPM, or one quart in 15 seconds coming out of the cooler return line before it goes back into the tranny

RustyJC · 12-08-2012, 08:58 AM

Quote:

Originally Posted by Arch Hoagland

I later bought a 2004 3/4 ton GMC with the 8.1 and Allison 1000. I pulled a 27' Komfort travel trailer with it.

It had a transmission temp gauge and I noticed it heated up the most in stop and go traffic.

Climbing mountains didn't seem to heat it up.

What has been your experience with heating in various driving conditions?

Transmission temperatures are largely a function of torque converter lockup. Fluid shear when the torque converter is unlocked generates TONS of heat; that's why stop and go driving results in higher transmission temperatures. Whenever possible, adjust speed, throttle position, tow/haul mode, etc. to ensure that the converter lockup clutch is engaged in order to minimize heat load on the ATF.

Rusty

wheels · 12-08-2012, 10:35 AM

Arch, Smokey Wren, Rusty JC - Mostly the heat rise has been in stop and go traffic, like you said. I agree with you Smokey Wren about placement of the sender - I just put this on as it was faster for the time being & rather than having no idea at all on transmission temp. Rusty, thanks for the information - I do find it quite helpful.

What are your thoughts for using the tow-haul button in drive or third when pulling a 19 ft. bumper pull that weighs approx. 4,600 with 5.3 1/2 ton Silverado?

Thanks to everyone who have responded & for sharing all the great information. Wheels