Tranny fluid in coolant

[THE DONALD]

Hi guys. I will keep it Short. I confirmed that there is transmission fluid in my coolant of my 2011 Tahoe LTZ. It has heavy duty cooling system for the transmission and oil cooler. What exactly do I need to do to clear the cooling system out of the transmission fluid? I do not see coolant in the transmission fluid, but do I have to change the transmission fluid as well? Do I need to have the dealership power flush the transmission? I hope that last time they did this transmission blew 200 miles later.

 

[OR VietVet]

If was me, I would flush cooling system and transmission as well. Because I am a "thousandaire" I would also replace the radiator with a Genuine GM model. Then I would monitor all these systems 2-3 times daily to be sure of repair. Also, change the trans filter.

 

[Geotrash]

If was me, I would flush cooling system and transmission as well. Because I am a "thousandaire" I would also replace the radiator with a Genuine GM model. Then I would monitor all these systems 2-3 times daily to be sure of repair. Also, change the trans filter.

100% exactly what I would do too.

OP, you may have dodged a transmission bullet by the slimmest of margins, but don't tempt fate. Get that fluid flushed right once you change the radiator and before you run that engine again. Lots of threads on here on how to do it.

 

[Just Fishing]

There is a warning in the GM manual that states coolant can destroy the seals in the transmission.
What that would mean would be slipping of the transmission.
As other stated; get it fixed asap, flush both transmission and the cooling system.

 

[Rocket Man]

My transmission builder (Performabuilt) voids their warranty if this happens because coolant destroys the frictions (clutches ) almost immediately. If yours isn’t slipping yet it most likely will start if you don’t get ALL the fluid changed out. There is a method where you can use the trans pump to pump all the old out as it refills with new. First pull the pan and get as much out as you can, and swap in a new filter. I haven’t done the fluid exchange but others here have. If you’re having the dealer do it, I’m not sure how they do the flush but I’ve heard it can be trouble. Either way, you need to get that fluid changed out. Good luck.

And you should update your other thread(s) and maybe add a link to this one.

Edit: I added a link to this thread in one of your others.

 

[YukonRog]

I'll just add when my transmission went out the lines to and from the cooler and radiator had to be replaced as well as the cooler and radiator before the new transmission went in. Hope it's not that bad for you. But check.

 

[Just Fishing]

My factory service manual does say the transmission needs to be rebuilt if coolant entered the system.

But it specified seals as the reason.

Now I'm curious.

I have some clutches left over from my rebuild, maybe i need to try soaking a clutch in coolant.

 

[Rocket Man]

My factory service manual does say the transmission needs to be rebuilt if coolant entered the system.

But it specified seals as the reason.

Now I'm curious.

I have some clutches left over from my rebuild, maybe i need to try soaking a clutch in coolant.

I’m sure that’s a bit different than getting coolant on the clutches while they’re in use but ok. I believe a company that’s been specializing in rebuilding transmissions for 30 years. If they say the clutches will go out soon after, I have zero doubt they will.

 

[Just Fishing]

I’m sure that’s a bit different than getting coolant on the clutches while they’re in use but ok. I believe a company that’s been specializing in rebuilding transmissions for 30 years. If they say the clutches will go out soon after, I have zero doubt they will.

Yes but for science!

Also to have some middle ground here.
If the seals go in the transmission, that will fry the clutches since the hydraulic part that holds the clutches in "Gear" will deteriorate.
Aka the piston seals (per the fsm).



So from a very high level, yes clutches will fail due to the clutch pistons not holding like they should.

 

[Rocket Man]

Yes but for science!

Also to have some middle ground here.
If the seals go in the transmission, that will fry the clutches since the hydraulic part that holds the clutches in "Gear" will deteriorate.
Aka the piston seals (per the fsm).



So from a very high level, yes clutches will fail due to the clutch pistons not holding like they should.

I think it’s more likely the fact that water or antifreeze isn’t good for hydraulics period due to the fact it doesn’t function as hydraulic fluid does so there’s not enough pressure being applied to the clutches. I know you can’t use water as hydraulic fluid. And an automatic transmission requires a certain line pressure from the (hydraulic) pump. Kinda like in this explanation I found using Google-foo:

“The Damage Done​

Automatic transmissions often succumb to seemingly slight deficiencies in fluid quality or quantity. Therefore, it is not surprising that grossly contaminated fluid can cripple the complex component. The fluid pressures required to operate and lubricate the transmission can not be achieved when the oil is diluted. The polluted fluid resists uniform compression necessary for hydraulic functions, and the transmission either slips in certain circumstances, or fails to engage at all. Lubrication failure can occur while underway, and the friction and resultant heat ruin vital transmission parts. Consequences can be less severe for the engine cooling system. Coolant function is compromised by the contamination, but overall effects are usually mild.”