View Full Version : Tranny fluid in coolant tank???

10-03-2009, 10:54 AM
My 03 Duramax 6.6 with the Allison tranny is causing tranny fluid to enter coolant system. Would this be a crack in tranny coolant line in the rad? Easy to fix or new rad??:dontknow: I expect its just like my Automatic 81 Jimmy or 83 GMC, just a lot more junk to re&re?

One day I hope to go wheelin at Stave rather just ask questions online!

10-03-2009, 06:43 PM
The problem is you bought a diesel with a bowtie on it.

10-03-2009, 08:03 PM
The most likely culprit will be the trans cooler has broken inside the rad, easy fix, replace the rad and DO NOT drive the truck until this is done....if coolant get's into the trans the water in it will simply kill the clutches n stuff.....

10-04-2009, 12:19 AM
fucked rad..........dont drive

10-05-2009, 09:43 PM
The problem is you bought a diesel with a bowtie on it.

Izuzu diesel, no bow tie.

10-06-2009, 08:05 AM
Thanks[cheers] , so far tranny oil clear still. But I'll have it flushed once I change rad and have flushed the cooling system a couple times. Taking rad out Wed and radman is going to check it out for me....

10-14-2009, 07:43 AM
So got "first rad" out that atf lines go into. Was told the aft line o-rings by a gm mechanic may be the culpirt but will have radman check it out today. Man the whole time I'm working on it I like my old 83 gmc more and more. Got the fan off but was wondering how tight to make it when putting it back on. The Haynes manual does not cover the duramax and getting the lower fan shroud out resulted in it coming out in 2 pieces, lol. So what is that 2nd rad for with the huge big pipes going into it? Coolant in there too? I'll need to flush all the atf out ogf the block, etc, any suggestions on how to do it? Do you flush it twice? Haynes manual says to take two bolts out of either side of block to drain block. Is that necessary? I'll pick up some cooling degreaser today I guess? I guess radman will know what to do?

dirka dave
10-14-2009, 12:51 PM
If possible put an aftermarket trans cooler in rather than the one in the rad.

They are more efficiant and will also allow you to have more tranny fluid in the system.

You also might want to change to transend, its an synthetic ATF. cost a bit but will also help out in cooling and extend the life of your transmission.

10-21-2009, 08:20 AM
Where do I get an aftermarket oil cooler? Does it actually still go in the rad tank or is it external?

11-02-2009, 06:04 PM
it would be external

11-03-2009, 11:30 AM
you would completely bypass the internal cooler and route your supply and return lines to the external one.

11-04-2009, 08:34 AM
I bought a whole new aftermarket rad for $430. New internal tranny cooler had a crack. One from GM was $335 and a GM rad $1400!!!!!! So far it seems no one is building a new aftermarket internal rtranny rad cooler just the external ones.

11-09-2009, 09:45 PM
try this its help me find a few parts for my rigs http://www.car-part.com/