Idea for trans cooler

GeneralTJI

Turbo Todd
Jun 1, 2010
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I already did the cooler flip mod... but had an idea for some extra cooling...

I have a small 12v Siemens electric motor I hooked to a small hydraulic pump a few years ago to build a scavenger system for a under-vehicle mounted turbo setup.. never ended up using this little gadget.

Got to thinking.. why not pull my pan, weld in some fittings and mount this sucker to the frame along with a cooler/fan back under the bed somewhere it's out of the way... put it on a switch so I only use it when towing or if temps were to get a little warm for my taste.

I have the Cooler already, and I have/can make hydraulic hoses as well so total cost at this point is 0.

I'm thinking this could work pretty well! Thoughts?
 

MMLMM

Tunergeek
Mar 2, 2008
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so you will pump oil from the pan back to a cooler and then back into the pan?

IDK. But I dont see this working quite good. I think it would have to run all the time to keep the oil circulated. And a lot of extra fluid too.

What are your thoughts on just picking up a new better cooler from Mike L?
I know you have the materials already so it would be a cost offset. But how bad are your temp now that you would need to do all the work?

What about a small cooler/fan in factory line?

what about mounting the fan from the cooler you have to your factory cooler???
 

ripmf666

Active member
Sep 20, 2006
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I see you pumping the fluid out of the pan and the trans starving for flid and sucking air at the filter. I looked at fliping the cooler it still gets around the same amount atleast with a chevy not sure about a gmc. But with the cut outs in the bumper it's still getting alot of air flow. I know my trans with the stock cooler runs 150 to 175 in 80 to 105 deg weather no matter if it pulling or not or going thru the mountains.
 

GeneralTJI

Turbo Todd
Jun 1, 2010
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It only seems to get as high as 170-180 when stop and go on a hot day. Normally around 150-160 I tweaked my tcu to lockup sooner even when not in t/h and that helped.

Getting ready to tow around 10-12,000 and wanted to be prepared.. may not be a big isssue (I don't tow that often, this is the first time actually... and usually it will only be my car/trailer which is around 6k ish)

I see you pumping the fluid out of the pan and the trans starving for flid and sucking air at the filter.
I'm not saying this because I know for 100% fact- but I don't see it starving the pan because a couple feet of line and a cooler can only hold so much oil and then it's being pushed back into the pan?.. might require adding a touch more oil (now that may present a problem when not running the pump though??) hmmmm

The only reason is for the cost.. I don't know how much a larger cooler from Mike is.... but the other coolers I have found that have the factory type connections were completely ridiculously priced IMO... I would be open to that option to keep the system simple if it's affordable!! I enjoy building everything I can and saving a little $$ when possible.

cooler flip mod ?

From what I read a few guys did this and reported a ~ 10 degree difference... again that is just what I have heard. I actually have not driven the truck since I did this... I will tomorrow and see if I notice any change.

what about mounting the fan from the cooler you have to your factory cooler???

I thought about this as well.. maybe getting a nice little 8" fan. Summit has a perma-cool (or some other name brand fan) for around $70 IIRC .... thinking that may help at least in stop and go traffic?

I'm just anal about my trans temp.. I have seen some transmissions burned up at lower temps than I would have thought it would take to do damage.... I realize a lot of people seems to push the Allison hard and get it very hot without damage.. but I don't even want to temp it if I can help it ya know.

Thanks for the feedback guys!!

Mike L if you see this can you PM me a price on your larger cooler?
 

Mike L.

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I have been reading this and have held back my opines because I may learn something. I don't believe in flipping the cooler on an '06 or later because it was lowered for two reasons. More fan action on the cooler when it is placed where the blades actualy pull air through it and not blocking the stack to help engine temps.
Steve Cole posted recently that I was full of shit when I called the cooler placement on the five speed a "dead zone" What I call the dead zone is the direct center of the stack where the clutch of the fan is centered and cannot pull air through. His words were it is only a dead zone at idle. DUH
Funny thing is; he runs my cooler on his truck. Imagine that.
 

Cougar281

Well-known member
Sep 11, 2006
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I'm not saying this because I know for 100% fact- but I don't see it starving the pan because a couple feet of line and a cooler can only hold so much oil and then it's being pushed back into the pan?.. might require adding a touch more oil (now that may present a problem when not running the pump though??) hmmmm

I doubt it... Once you put the additional lines and system in place and prime it, it'll be full of fluid weather or not the pump is on, so if you where to install it, I don't think there'd be any real impact on the fluid level. How effective it would be at cooling the fluid in the pan is another story.
 
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turbo_bu

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Mar 27, 2007
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It's all heat. So, if you can plumb it up and maintain the fluid level in the pan without adding extra airation (spelling?) to the tranny fluid, yes it will work. You are simply adding on an extra cooler. Although it is actually, an extra pump, lines and cooler.

Now, how much extra cooling / lower fluid temperatures you are going to see will be dictated on size of cooler, flow of fluid and amount of cooling air going across the cooler.
 

Mike L.

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The temperature of the fluid in the sump will be about 20-30 deg cooler than what you see on your dash gauge because the temp sensor is on the PSM and you are reading partial heat sink. The cooling effect with this gizmo may not be as dramatic. I would keep the pump prssure very low so as not to create any bubbles when the fluid returns to the pan or you will wind up heating the trans further.
 

GeneralTJI

Turbo Todd
Jun 1, 2010
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I am seeing a drop after doing the cooler flip... most of the testing I did this weekend was cruising (not much city). It was up to 94 degrees outside and it was holding at 160.

As the outside temp cooled down to 80 the trans dropped to 150. This is a good 10 deg+ drop in temp. I didn't get enough stop and go in to make a claim there.. (didn't seem any higher).

But this was also just unloaded driving (which of course didn't require the fan to come on etc)

I'm still considering trying this setup, by I may wait until I pull something heavy and see if it's even needed :thumb: I do appreciate the input guys.

BTW, a family friend just had his 7.3's auto fail for the 2nd time... I got to looking under the truck (it's a f350 btw) and it has NO trans cooler... outside of radiator "cooling"

I may be installing a cooler on his truck real soon, he doesn't want to rebuild it a 3rd time :mad:

WTF were they thinking.. they don't even lock up the tc under heavy loud or any gear but 3rd and 4th IIRC?!
 
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Mike L.

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I am seeing a drop after doing the cooler flip... most of the testing I did this weekend was cruising (not much city). It was up to 94 degrees outside and it was holding at 160.

As the outside temp cooled down to 80 the trans dropped to 150. This is a good 10 deg+ drop in temp. I didn't get enough stop and go in to make a claim there.. (didn't seem any higher).

But this was also just unloaded driving (which of course didn't require the fan to come on etc)

I'm still considering trying this setup, by I may wait until I pull something heavy and see if it's even needed :thumb: I do appreciate the input guys.

BTW, a family friend just had his 7.3's auto fail for the 2nd time... I got to looking under the truck (it's a f350 btw) and it has NO trans cooler... outside of radiator "cooling"

I may be installing a cooler on his truck real soon, he doesn't want to rebuild it a 3rd time :mad:

WTF were they thinking.. they don't even lock up the tc under heavy loud or any gear but 3rd and 4th IIRC?!

The 7.3 has a worthless trans cooler but it is there behind the stack. Trick setup is the 6.0 trans cooler but it will have to be adapted from 1/2 to 3/8 line which is easy. It is also a bolt in.
 
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NemesisDP

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Apr 20, 2008
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On my trip to Cali this last week my tranny temps would run @ 200 in temps over 98deg. Went to PPE to pick up an old LBZ turbo I had there then left to Vegas. On the way my trans temp got a little over 200 and my fan kicked on but motor was at 190. Will the fan come on if the trans gets hot? (07 lbz) Thanks:hug:
 

Chevy1925

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Oct 21, 2009
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The temperature of the fluid in the sump will be about 20-30 deg cooler than what you see on your dash gauge because the temp sensor is on the PSM and you are reading partial heat sink. The cooling effect with this gizmo may not be as dramatic. I would keep the pump prssure very low so as not to create any bubbles when the fluid returns to the pan or you will wind up heating the trans further.

AH this makes a bit more sense to me now. would it be safe to assume this is why you dont see the factory trans temp gauge move very quick to show a cooler temp when fan kicks on and you no longer have a load on the truck runnin down hill after you jsut pulled a long hot hill with a heavy load?

Got another question to add to this thread. Now obviouly a tranny is much different than a engine but, does our allison run/work better at a certain tempature than others? As in, if the temp is too low, will it not work as well? Now i know 190* is probably better than 200* but i guess im pertaining this to like a gas truck. the ECM is setup to give the best power at 195-210 degress, too cold power is backed down, too hott and power is backed down as well.

just a thought i had and its probably something im way off base of but if you dont ask, you will never find out :D.