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How To: I bypassed my Transmission cooler with an external

Firesquirt

Well-Known Member
Messages
46
Location
La Quinta Ca.
I was concerned about the dreaded transmission cooler problem so I installed a B&M Supercooler, bypassing the transmission cooler in the radiator.
The convention I use is looking into the engine compartment from the front of your Hummer. So right side = Drivers side, also this is for USA.


You will need;

  • Music.
  • Flair Tool.
  • Socket set (metric)
  • 2 Quarts of replacement transmission fluid.
  • 4 5/8 inch hose clamps (the ones in the kit are no good).
  • Drill and bits.
  • Hose cutter.
  • Pipe cutter.
  • Oil catch pan


Also, as I was dismantling the grille I broke two of four retainers, You may want to purchase these ahead of time, they seem to be special order from the dealer.

Part No. 11561829 Retainer. $8.82 each. Total of 4.

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The Kit I bought is B&M 70264 Transmission Soopercooler 24000 GVW and 14400 BTU. I bought it from JEGS for 65.99 + Handling.
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The reasons I chose this one is that it is a stacked plate design, good BTU disbursement and built in bypass.
Per B&M they state “The cooler will guard against excessive overheating, but will not overcool the transmission in winter weather”


So first off remove the skid plates to give yourself access underneath.
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This what you will see from underneath
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Now you need to remove the tow hooks.
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Now you have access to the hook bracket and brush guard mount, If you have a brush guard, loosen the bolts only at this point, otherwise go ahead and remove them.
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Once the bolts are loosened lift the brush guard up and set it aside, now go ahead and remove the four bolts all the way and set aside the brackets.


On the back side of the grille from under the hood remove the bolt on each corner.
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Now remove the two bolts at the top of the grille from the front.
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Now remove the two bolts in the first bay of each side of the grille.
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Now pull straight out on the grille at each side around the headlights, be careful this is where I broke my retainers.:whaa:
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Set the grille aside in a safe place.


Place the cooler in the area you want it and mark the area where you want the bracket attached. Now center punch and drill your holes in the desired locations.
IMG_0332.jpg



Now attach the cooler brackets to the vehicle and then attach the cooler to the brackets.

I used rivets.
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Take the cover off of one of the barbs n the cooler, slip a clamp over the 5/8 inch hose and slip the hose over the barb, tighten the clamp and route the hose between the radiator and frame (there is enough room).

Now from underneath, remove the C clip located in the groove of the transmission connector in the bottom of the radiator.
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Put an oil catch in place under the cooler lines as transmission fluid will freely flow when the line is disconnected.
Now pop the transmission pipe from its retainer under the radiator and the connector will now pull right out of the radiator.

Hint:
I used the plugs that were on the cooler to place over the end of the lines to reduce the amount of ATF lost.
hint.jpg



Cut the transmission line at the desired locations.
Remember now that the transmission line on the DRIVER SIDE gets connected to the BOTTOM of the cooler and the PASSENGER side line gets connected to the TOP, otherwise air locks may occur inside the cooler and you will not have desirable results.
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Now flair the ends so that your clamps have something to grab onto.
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Cut your hose coming from the cooler to length, keeping in mind which hose goes where. Slip a clamp over the hose and slip the UPER hose over the passenger side pipe or the LOWER side hose over the driver side pipe, tighten the clamp.
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With the other half of the 5/8 inch hose repeat on the other side of the cooler and attache it to the other side of the transmission.

I made a plugs for the radiator out of the ends that were in the radiator before and placed them back in using the C clip to secure them.
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Once everything is in place start the engine and check for leaks.
Put the transmission in neutral and check the fluid level add as necessary.
When satisfied that there are no leaks put the grille back together in the reverse that it came apart.

I hope someone finds this useful.
 

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Last edited:

Happy Hummer

Well-Known Member
Messages
1,300
Location
Wisconsin
Have you had any problems with this setup?
I followed your thread pretty damn close and came out pleased with end results.
I'm wondering if 24k 14400 is enough cooling capacity though?
Some forum members feel it is too small.

Chris
 

Zach

Mall Crawler
Messages
4,812
Location
So Cal
I thought only H2's had this problem..

H2's are not common to leak on the trans side. It is common to leak from the fittings on the oil cooler side. Have already replaced my radiator, problem fixed. Radiators have come way down in price since I did mine a few years ago
 

RamRod

Well-Known Member
Messages
3,914
Location
AB, Canada
I believe the reason that you want to cut the lines is so that you can make plugs for the radiator to prevent it from getting contaminated now that trans is unhooked
 
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