Curt
Sometimes when I close my eyes, I can't see.
Hummer H2's have a built in transmission temp gauge in the cluster. When towing on hot summer days pulling a 5000 lb trailer it'll reach a temps of 240*F+. Been that way since 2005 when we bought it and haven't had any transmission failure yet. Yes, I know... yet.Have you ever measured the temperature of the trans fluid in the pan?
How do you know you need a cooler that enormous?
4L65e in a 2003 Hummer H2.What tranmission are we talking about here?
Which cooler do you recommend? The link leads to a transmission temp gauge.I recommend this cooler.
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The sending unit is mounted in the provided "T" fitting in the cooler line coming out from the transmission.
The pan location for the sending unit can lead to a false sense of security.
An aggerated absurd example follows;
The fluid comes out of the transmission at 4000 degrees Fahrenheit.
Then it goes through a cooler the same size and shape as Nebraska.
It dumps into the pan @ -40F.
Your pan mounted temp sender says 180F.
You never knew it got hot.
The transmission temps I'm basing my needs for cooling off of is the factory transmission temp gauge located in the cluster of the H2's. It sounds presumptuous when I say this, but I don't intend for me to come off this way. But you would think GM would make sure the transmission temp gauge would read accurately, right?
I agree, high temps kill transmissions. I've experienced in real-time how quickly temp will smoke a transmission. That's going down a rabbit hole of a conversation though haha. As for that derale thermostat, I can confirm it works great. I have the Derale 13011 on my suburban and has performed flawlessly. Would highly recommend that setup. More info on my transmission cooler setup on my truck here:https://www.gmt400.com/threads/time-to-get-serious-with-4l60e-4l65e-cooling.50138/What's most important is the temperature of the fluid being picked-up by the trans pump to be squirted through all the trans passages--valve body, converter, clutch packs, governor, etc.
THAT fluid should be in that 160--200 degree F range.
Putting the temperature probe in the hottest fluid produced by the trans leads to panic, which leads to people buying MUCH more trans cooler than they need. Which leads to higher Corporate profits, but not much improvement in actual trans life.
I was told a slightly-different version of this way back when I was in trade school. At that time, it started at 170, not 200. (So by 190 degrees, trans life was already halved.) I've found versions of this that go all the way back to the late 1950s when ATF was still based on whale oil.
I don't think it's accurate any more. Fluid, trans seals, etc. have improved. Modern transmissions routinely go 200,000 miles or more, with reasonable maintenance (when they're not based on the "700" or "200" design--which isn't really a fault of the fluid or fluid temperature.)
Here's an example:
If that temperature/trans life correlation was EVER accurate, I think that NOW it's mostly scare-tactics to sell people stuff they don't really need.
Probably works great for trans coolers. Kinda thinking about getting one, now that you've pointed it out. OTOH, I've got no trans problems to blame on too-cold fluid. I've popped a couple of TH700s in my K1500 which I blame on the basic, weakass TH700 design; and one 4T60E that I blame on flat-towing the car too far when the car broke down.
I'd be scared to death to use it on an engine oil cooler. 3/8" inlet and outlet would murder oil pressure in a full-flow system. My L29 uses 1/2" tubes to the internal radiator-mounted oil cooler.
As for the Hummer, it's on 38x15.50x18's. Just driving around town trans temp will sit at 195*F. On top of that, it's a boosted 6.0 pushing power through a 4L65e. Been going strong for 50k miles now with these temps and being boosted at birth, will correct the transmission if/when it goes.
Right now the max cooler size I could squeeze in that tiny space would be 22"x8.5x2". I haven't had any luck finding a cooler with a built in t-stat yet.They make coolers now with the t-stat built in . They flow 1/4 of the cooler until temp opens the internal valve then its 100% cooler flow . Easy to plumb and less work and fittings .
As said what are current temps ? 40k cooler on a 4L60 based trans in my opinion is a lot . If your making that much heat there is other things to look at first .
Current temps are about 250*F on the trans temp gauge when towing. Coolant temp sits at about 235*F and will continue to climb if I don't let off during a hill climb. These temps are achieved during hill climbs on 100*F+ days. The truck is supercharged pushing 5 lbs of boost, has a 4" lift on 38's, towing a 5000lb load + cargo. Funny enough, it sounds like my luck with temps and towing go hand-in-hand leading to all fingers pointing at my driving style, but I've followed all the driving techniques that I know of to not only prolong a life of a 4L6xx transmission while towing, and keep temps as low as possible.
The real issue is having trucks that are not 100% focused on towing only. We don't tow enough to warrant a tow dedicated vehicle.
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