Can ATF leak into the cooling system on a 2003 Accord V6

Tiny
NAVYDOC8425
  • MEMBER
  • 2003 HONDA ACCORD
  • 16,000 MILES
My car has brown colored coolant, and having transmission slipping. Transmission was very low on fluid. Replaced fluid. Flushed out cooling system. Car drove very well for about seventy miles. No transmission slipping. Then started slipping again. Looked into engine compartment and more brown being forced out of the coolant reservoir and transmission was very low on fluid again.
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Wednesday, November 16th, 2011 AT 5:38 AM

6 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
The transmission cooler runs through the radiator. There must be an internal leak there. This needs to be repaired ASAP because it will take out the transmission.

Check that for me. If I am correct, the radiator will need replaced.
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Wednesday, November 16th, 2011 AT 5:42 AM
Tiny
KHLOW2008
  • EXPERT
This model does not have hoses to the radiator. There is a cooler/warmer that is attached to top of transmission. That unit should be faulty and requires replacement.
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Wednesday, November 16th, 2011 AT 11:44 AM
Tiny
NOELNOCHIM
  • MEMBER
I am having the same problem with ATF tan sludge in coolant. The coolant hoses were all replaced and the system holds pressure. The car holds temperature for a while then overheats and spews tan colored fluid to the reservoir. I think that the ATF pressure is much higher than the coolant pressure (13 psi -ish) so the ATF leaks into the cooling system. Do you know if there is a history of leaks in the ATF warmer? There are a couple of "o"rings between the warmer case and the mounting to the transmission and ATF could leak into the coolant there. Whatever is causing the leak, the problem does not appear until some miles are put on the car. The last occurrence occurred six miles after the engine first came up to temperature and the thermostat opened. Thanks for taking the time to respond. Noel Nochim
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Wednesday, February 22nd, 2017 AT 11:57 AM
Tiny
KEN
  • ADMIN
Hey Noel,

I would bypass the warmer/cooler and drive the car for a short time to see if transmission fluid is leaking from the warmer/cooler. Use a short piece of tube as the splice.

Please run this test and get back to us so we can continue helping you.

Best, Ken
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Friday, February 24th, 2017 AT 2:12 PM
Tiny
SIHOTA
  • MEMBER
Hey Noel,

Did replacing the ATF warmer solve the problem or how did you go about fixing it? Hope to hear back, thanks
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Wednesday, April 18th, 2018 AT 7:42 PM
Tiny
KEN
  • ADMIN
Hello,

I am sure it did. it is the only thing that can allow transmission fluid into the radiator. Here is a guide to help you see what you are in for when changing the radiator out:

https://www.2carpros.com/articles/how-to-replace-a-car-radiator

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken
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Thursday, April 19th, 2018 AT 10:20 AM

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