Auxillary Tranny cooler on 4l80E

[White Knight]

Hey boys and girls,

 

I am putting in an extra cooler for the tranny. My question is which line should I tie into? My initial thoughts was to do it on the return line from the factory auxillary cooler. It appears it would be an easier run of hoses and cleaner install, but my mechanic "friend" said I should tie into the upper radiator tranny line. (Did I confuse anyone there?) He thinks it would be better to for fluid flow. I can see his point but the other way is so much easier. Tell me what you have done or what you would do. Thanks

 

It's supposed to rain all weekend but I am going to get it done, regardless!

 

I will of course take pictures so everyone can see what I did.

[ChevyTech007]

I would think that either way would work. It would be better to put it in the line before the radiator cooler. My thinking on that is that you would be removing a lot of the heat before it went into the radiator. Might help it run a little cooler. 2 cents worth.

[White Knight]

Well, it's done! I took pictures and when I get the time I will post them in my garage for future reference of what needs to be done to install one of these puppies. It was relatively painless, it didn't go as quick as I thought it would but few things ever do. I will post pics later, ya'll have a good weekend.

[Burbman]

Curious as to why you needed an aux cooler....my 4L80E never goes over 200 deg, even when pulling 9000 lb RV uphill or in traffic.

[White Knight]

Burbman,

 

The reason I put a cooler on was for three reasons:

 

1) I was towing around 7k two weeks ago through town and saw temps rise to 210 when ambient temp was 60. Granted it was alot of stop and go but I still dont want to see temps raise that much.

 

2) I tow a 31' TT during the summer, when I go up and down hills that temp will rise even more. I was towing the TT with a 02 2500HD 6.0 this fall and had to get out of the gas so the temps didn't rise past 215.

 

3) You can never have to cool of a tranny. The only concern is not getting the temp up to operating but so far I haven't had a problem.

[Burbman]

Got it. Possibly the 8.1 comes with a bigger trans cooler due to the bigger radiator? Our TT is 34', and hiway driving will put the trans right around 175, but it will go to 200 if I'm pulling a long hill in 3rd gear, or if I get stuck in traffic. You can actually see the trans temp go down when you start down the other side of the hill.

 

Last summer coming back from VA Beach we ground to a halt in B-to-B traffic for the GW bridge afrer running at 65-70 for hours. Outside temp in the rearview said 104 (I think it was really 95, that thing always reads warm), and trans temp never got over 200.

 

I would have added the cooler also if I saw the temps you indicated. Can't wait to see the pics.

 

I flush the fluid every year in the spring beafore towing season just for extra insurance anyway.

[Frozen001]

Burbman,

 

3)  You can never have to cool of a tranny.  The only concern is not getting the temp up to operating but so far I haven't had a problem.

 

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Actually this is false....Too cold is just as bad as too hot.... That is why all factor installed coolers are before the radiator line which helps to bring the temperature up during colder weather.

[White Knight]

In the colder months, I agree with Frozen001, that is why I do the quick disconnects so in the winter it will only take me 5-10 mins to unhook the big cooler and hook it up the way it came from the factory. I drove with the trailer behind me today in stop and go traffic for about 30 mins or so and it never broke 150.

 

I have contacted the service department to ask what is the normal operating temperature of the 4l80e and they say around 200 is fine. I don't think they understand my question or it's the guys first day behind the counter. Does anyone know what is too cold for the 4l80E.

 

I have some of the pics done in my garage, but the girlfriend took me away from the computer the other day and i just haven't gotten time to go back and finish it.

[bdeboer]

White Knight, what transmission cooler did you use? I have experienced similar numbers on my 6.0L suburban.

 

Thanks

[White Knight]

Tru-cool 4730 Max, is what I put in. I got it from the dieselsite2.com last year. I initially put it on my old powerstroke but then took it off in case I would need it on this truck. Which I did. Good luck

[Mattt]

I'd be interested to see the pics of the install.

 

I tow a 29' toy box trailer(~9-10k) with my 01 2500hd 6.0, and Im always watching the trans temp. Truck by itself never breaks 200. But towing is another story. Flat land, average fwy towing puts it at 200. Any hill, or prolonged 3rd gear run brings the trans up as high as 230. I talked to my mechanic about it, and he only had one question. "Once it reaches 230, and you get over the hill, etc,,,,does the temp drop back down?" It always does, so he said not to worry about it. I went to him asking about installing a larger than stock cooler, but he said the system is doing its job. Heating up, then cooling itself back down. I wish I had the 8.1, Im sure its working much less hard, but Ive got the 6.0 and Im making do. I would imagine the 8.1 has a larger cooler in the radiator.

 

Anyhow, what did the cooler run you, and how tough was the install?

Thanks in advance.

[Frozen001]

Found this on the net... pretty much sums up how heat effect transmission wear

 

Automatic transmission fluid will provide 100,000 miles of service before oxidation occurs under normal operating temperatures of about 170°F. Above normal operating temperatures, the oxidation rate doubles (useful life of fluid is cut in half) with each 20° increase in temperature.

 

The approximate life expectancy at various temperatures is as follows:

 

Temperature Life expectancy

175°F 100,000 miles

195°F 50,000 miles

212°F 25,000 miles

235°F 12,000 miles

255°F 6,250 miles

275°F 3,000 miles

295°F 1,500 miles

315°F 750 miles

335°F 325 miles

355°F 160 miles

375°F 80 miles

390°F 40 miles

415°F Less than 30 minutes

 

This information clearly shows why transmission oil coolers and the various maintenance intervals are recommended for severe usage.

 

Above 300°F, the metals inside the transmission will warp and distort in varying degrees depending on the severity of overheat. Because this damage occurs and fluid life is so seriously impaired, rocking out of snow, mud or sand should never exceed a few minutes.

 

Synthetic fluids are better but can still be compromised under extreme conditions.

 

As far as being too cold I believe it is because cooler temps mean "thicker" fluid, means increased pressure which can blow seals. Also there is the effect of getting rid of any water in the system with the higher temps.

[mmmikkke]

As far as being too cold I believe it is because cooler temps mean "thicker" fluid, means increased pressure which can blow seals.  Also there is the effect of getting rid of any water in the system with the higher temps.

 

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I think there's a sweet spot between 140-170 where you want to run. If you run colder than that, you'll lose fuel efficiency due to fluid viscosity, and your shifts will be prolonged, increasing clutch wear.

 

Some add-on trans coolers come with thermal bypass valves that bypass the cooler when ambient temps are below freezing.

[Burbman]

Frozen, Good info, here it is in chart form:

 

[snoman]

I think there's a sweet spot between 140-170 where you want to run.  If you run colder than that, you'll lose fuel efficiency due to fluid viscosity, and your shifts will be prolonged, increasing clutch wear.

 

 

Actually the sweet spot is between 170 and 190 as 180 is considered ideal and 140 is too cool to keep moisutre from condesation evaporated out of fluid. YOu do not want to be above 220 or so for long as it can shorten seal life in tranny (which they never mention in tranny fluid temp charts) TMep above 250 o0r so can cuase seal damage in short order even if you have SYN fluid that can take the heat.