Tranny Fluid and Coolant Mixed after Tranny Service

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2010CTS
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Joined: Wed Feb 14, 2018 2:09 pm

Tranny Fluid and Coolant Mixed after Tranny Service

Unread post by 2010CTS » Wed Feb 14, 2018 2:13 pm

Is there any way a shop might have screwed up a transmission flush so badly that it would have caused the engine coolant to mix with the transmission fluid? 100,000 mile recommending tranny service on a 2010 CTS. Radiator got flushed every 2 years like clockwork with zero signs of aging/wear/rust. Could the shop have caused this issue?

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carriedi
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Re: Tranny Fluid and Coolant Mixed after Tranny Service

Unread post by carriedi » Thu Feb 15, 2018 2:57 am

anything is possible but what has a shop done to make you think that?

who said that you have coolant in the transmission fluid? what made you think that you had a problem? Transmission problems? Cooling system problems? Transmission fluid in the cooling system?

are you using dexcool? should be 5 year or 150K miles according to GM

how old is your vehicle? And mileage. is it possible that your trans cooler is damaged?

Year, model and engine would help to look up specific problems
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2010CTS
Posts: 2
Joined: Wed Feb 14, 2018 2:09 pm

Re: Tranny Fluid and Coolant Mixed after Tranny Service

Unread post by 2010CTS » Mon Feb 19, 2018 8:19 am

2010 CTS Base Model. 3.0L V6. I had the 100,000 mile tranny service done (as recommended in the manual) back in December. Never had a single problem with this car before. Noticed a faint smell when we got the car back, but just figured they got some fluid on the exhaust and thought it was just burning off. 10 days ago, the transmission had major trouble shifting while my wife was on the way to work. First time there was any noticeable issue. Get the car towed to the shop. They raise it up. Tranny pan is crushed. Not a scratch on the pan or the exhaust or any of the other parts that hang lower than the tranny pan. Only the pan was dented in. Original thought was, my wife ran over something, but with no other marks under the car, highly unlikely. More likely would be that the shop lowered the car down on top of something (didn't clear the floor before lowering it) because it looks like someone tried to jack the car up by the tranny pan (which would be impossible to reach with any jack I've ever seen). Then they call me back the next morning and they show me all of the pink milkshake that came out of the cooling system. They said the engine coolant and tranny fluid mixed. My question is, could the crushed pan have reduced the transmission's fluid capacity and caused a high-pressure situation that would have caused the fluids to mix at the radiator since they are both cooled there and only separated by what is probably a very thin wall? They're telling me is common for this mixing to happen even without damage. What do you think? Thank you.

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carriedi
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Re: Tranny Fluid and Coolant Mixed after Tranny Service

Unread post by carriedi » Tue Feb 20, 2018 7:17 am

a dented trans pan won't reduce the capacity if the capacity has already been filled. it will raise the fluid level by the volume that the pan is dented in. is the dent blocking the filter in the trans? (Would have to be a very bad dent to do that)

I don't know what a shop would leave under a vehicle that would dent a tranny pan but I guess anything is possible. Usually when you lower a vehicle down on a lift you can't help but see the floor as the car goes down. Maybe if they have very old lifts that don't have the safety releases that require to hold as the lift goes down and lowered the vehicle without being there. But, like I said, almost anything could be possible.

finding where the coolant entered would be main concern. If the radiator is suspect you may change the radiator and then take the old radiator apart and look at the trans cooler inside the radiator.
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