Tranny cooler installation

[Egan]

Originally Posted by chris4851

Correct. What is the cooler in Step 1 above, which is attached to the two vertical brackets? I believe the power steering cooler is to the right of this cooler. Also behind this cooler is another cooler then the radiator. What are they all for?

[SummitUp]

Well done Egan, and I stand corrected, there definitely was/is an OEM external tranny cooler:

[Egan]

Originally Posted by SummitUp

Well done Egan, and I stand corrected, there definitely was/is an OEM external tranny cooler:

It's a wonder any air gets to the radiator.

[LoJac963]

so why has no one just bypassed the in radiator portion and just used the OEM tranny cooler? Is it not efficient enough on its own without the radiator portion??

[chris4851]

Thanks for all the help. I am at a standstill right now. I was thinking of the aftermarket transmission cooler. Now it looks like it may be possible to utilize the stock transmission cooler and just bypass the radiator all together. This seems like the simplest solution to fix any potential fluid mixing issue. Does the radiator add any additional cooling for the transmission fluid which would pose a problem if bypassing with the stock cooler? As Lojac mentioned is this less efficient which would require a larger aftermarker cooler?

On a side note I do not take my H2 off road and very rarely, if ever, tow anything significant for long periods of time. I really just want to fix a potential issue with fluid mixture so I know my transmission is safe in the long run.

[SummitUp]

I've been on this and all the other Hummer forums for several years now and I've never read a post or a thread where anyone has bypassed the radiator portion of the tranny cooling circuit while keeping the stock cooler. I myself would not feel comfortable doing it, just looking at the stock cooler it looks pretty small.

You could always go ahead and do this and become the first "beta tester"!

[chris4851]

Normally I would jump at the shot to give this a try. However I was trying to get this all done before I head on a road trip. Don't really want to beta test anything being a thousand miles away from home.

[iwillnc]

That would tell me that the factory cooler is more than likely sufficient as is.

[LoJac963]

I would imagine so especially if you rarely offroad or tow anything. I've been meaning to add an aftermarket cooler but I think I'll bypass the in radiator and see how the temps run.

The real test will be this summer here in AZ but again I don't forsee any issues using just the external.

I'll try and take pics when I start this project if no one beats me to it.

[Hellz]

so i am looking to add an external cooler to my 2003 H2.

here is a pic of my front end. it looks identical to the pic of the 2005 H2 with a external cooler ( OEM)

do we know for a fact this is an external Tranny cooler?

im not worried about bypassing the radiator and going to this cooler, as i am more concerned that if this is indeed for the tranny, i want to pull it out completely and install a bigger cooler right where it is located at and using the brackets in place to mount to.

[Ice]

I am considering doing this also. Would I see any benefits by just replacing the stock cooler with a larger one and not bypass the transmission or do you get better cooling by bypassing the the radiator?

[Egan]

Originally Posted by Ice

I am considering doing this also. Would I see any benefits by just replacing the stock cooler with a larger one and not bypass the transmission or do you get better cooling by bypassing the the radiator?

The whole point of this is to bypass the radiator to eliminate the chance of coolant mixing with tranny fluid and destroying your transmission. The external cooler is an added benefit for better cooling.

[iwillnc]

As I quickly approach the need I do this myself, I've been thinking; obviously what's there is flawed and must be fixed, however I looked into why it went the way it did, while in sure many have long since figured it out, I just felt reason to state what I found
The factory unit allows the teams to heat up faster when cold, it's just as important for the transmission to be heated to a level as it is to cool it.
The factory unit also cools by use of liquid which inheritaly (sp) cools better than air

So by using just the stock external you lose the heating properties and a certain amount of cooling

Regardless of this, the system must be altered

[Hellz]

Originally Posted by iwillnc

As I quickly approach the need I do this myself, I've been thinking; obviously what's there is flawed and must be fixed, however I looked into why it went the way it did, while in sure many have long since figured it out, I just felt reason to state what I found
The factory unit allows the teams to heat up faster when cold, it's just as important for the transmission to be heated to a level as it is to cool it.
The factory unit also cools by use of liquid which inheritaly (sp) cools better than air

So by using just the stock external you lose the heating properties and a certain amount of cooling

Regardless of this, the system must be altered

im not sure that it is important for the tranny be heated to a certian level for operation. now if we are talking well below zero degrees, thats another issue.

i live in Minnesota, it is freezing or below freezing nearly half the year here. hell, we are expecting 8 inches of snow by tomorrow.. APRIL 11th !!!!
my tranny works and had always worked without issues when it is cold.

with my cooler installed.. i have seen the temp go up to about 120 degrees, but that is the max. 90% of the time though the needle doesnt move. it just sits right at the 100 degree mark.

by natural friction, the fluid/tranny will heat itself up to its rated viscosity. any additional heat besides that, that is the heat that needs to go.

[iwillnc]

How much fluid did you guys have to add to the system?

[iwillnc]

For goodness sakes, I'll be the beta tester then, I have the tru-cool in the backseat, but being worried about the A/C condensor flow, and the fact I feel 120 is waaay to low, I'm going to try using the factory cooler

As is my tranny never goes above 180, And I would be very happy at that temp as 175 is considered optimal tranny temp from what I see.

I don't want to regret spending $150 on a radiator, but I would be very happy if this worked.
But seriously the stock cooler is not THAT small.


Also if you never get it up to temperature it won't be able to get rid of the moisture in the transmission fluid, as well as it won't allow the TC to lock up as it's suppose to.

[LoJac963]

valid points, I think as I mentioned before (pretty sure) just bypassing the radiator and using the stock external cooler should suffice. I need to do that myself because all the bad stores of antifreeze and tranny fluid mixing scares me lol

[jsbihn]

Have any of those who have just used the stock external cooler to bypass the "mix" have anything to report back on this?
How are the temps?
Is the cooler shown in the 2 page of this thread by Hellz actually the tranny cooler for the 03 also?

I am looking to do this and right now I want to just make sure I avoid the "mix"

I figure afterwards if I need more cooling or something, I can replace it but for now I want to make sure it is taken out of the loop.

[jsbihn]

anyone do the bypass just using the stock cooler? and is the cooler that Hellz has pictured the tranny cooler?
Like he said, I would hate to bypass it and it turn out to be something else.

[iwillnc]

Update, I've done the loop to stock cooler avg temp is 178 so far has got up to 185.

Outdoor temperature is about 80 F

At the moment I can't say whether this is a success or failure, although its leaning toward a failure, I'll know for sure when the outdoor temps hit 95+
I'd like some wiggle room on the temp, I'm sure the stock would be fine if your max temp was 70, but I'm not sold on it as is.

If at any point the temp hits 200 then I will be putting on my aftermarket cooler.

Driving varies between in town to country roads

If my max temp when outdoor temp gets to 90+, never goes above 190 then ill be adding a deeper pan, I haven't been offroad yet but I'm sure it would get hot

Quite honestly I never paid much attention to the trans before other than periodically checking it wasn't above 200, so if these numbers are normal, I can't say.