Tranny cooler installation

[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]

Off topic but...

To the guy whose H2 is in the picture a commong problem with early H2's was the hood straps rotting out because of the factory "sleeve" over the wire, which was corrected but cutting the sleeves off so that the metal cables could dry properly.



And I'm very intrigued on using the stock cooler, my 03 is still under warranty and I don't want a reason for them to deny fixes so I'm waiting til it is almost up, which it is now getting to the point that it is almost up...

[chris4851]

I spoke with a local transmission shop about the issue I am having utilizing the stock cooler and bypassing the radiator. For what it's worth he mentioned the radiator is typically used to regulate the coolant temperature before it returns to the transmission.

[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.

[Ice]

Thank you! Now I understand.

[Hellz]

so what level do you guys keep your tranny fluid at now with the cooler?

i had my cooler installed now for about 2 weeks, and this baby keeps the fluid cold.. well under 100 degrees.

so if the fluid is kept cold, it never expands.

right now, i have it just above the cold line.. like 1/4 a quart above.

im also chasing a leak somewhere in it, but can locate it due to the fluid slopping around for a little bit. so i power washed the whole area, and wiped down the lines in hopes i can track it. since i didnt cap off the internal rad lines, im guessing that excess leaked out, but i did have to add fluid.. so who knows.

but i am curious at what levels you guys run it at.

thanks

[SummitUp]

I just keep mine at the "full when hot mark" when the truck is running at it's at it's hottest (about 140? - 150? for me).

[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]

Anyone tried stock yet?

[iwillnc]

120 just seems way too cold for the transmission