I've read the posts on radiators leaking and tranny fluid/coolant mixes somehow. How does this happen? Does Volvo route coolant pipes through fluid or vice versa? Doesn't seem physically possible. Both should have separate radiators it seems.

 

In a lot of vehicles with automatic transmissions they will run the transmission fluid through a cooler that's located in the radiator thus using the coolant / air flow to cool the tranny fluid. In more performance oriented / better designed / heavy duty vehicles this is done with a separate unit (my 92 Land Cruiser has one). This allows more efficient cooling for both tranny fluid and coolant and avoid just this situation. Simple common sense in my mind.

Anyway in some newer cars where everything is cheap plastic or thin aluminum the lines in the radiatorcan leak allowing tranny fluid to pump into the coolant when the car is running (transmission lines are under higher pressure) and the coolant into the tranny fluid when the car is off due to the coolant retaining pressure after the vehicle is off.

Besides the obvious issues of dirty coolant and loss of tranny fliud there's the extra bonus of the fact that the coolant eats away at the seals in the tranny and the tranny fluid eatsaway at the rubber hoses in the cooling system.

The end result if left untouched istranny and cooling system failure...thus the over the topcrazy quote from the local Volvo dealer of about$6000 to replace radiator, hoses, and trannyLMAO HAHAHAHA. Let's see $6000 repair on a car that mayhave a trade in value of $15,000 and is leased, right. How about $180 for a replacement radiator,throw it in there, flush both tranny and coolantand we're good to go.

 

So they are cooling the tranny fluid with 200 degree coolant? Or are the two fluids run side-by-side in separate tubes (or a walled tube) so both get airflow over them? Does the radiator itself have separate hookups to coolant and tranny fluid?

 

Both the coolant and air cool the lines, I don't know exactly how it's layed out in the radiator but in order to mix the coolant and tranny fluid have to be close. Yes the radiator has separate hook ups.

 

Yes, they run a coil through the radiator.Warms the tranny up faster and keeps itat a consistent temperature.

 

Thanks, I've always driven manuals, so never have seen a radiator like that! Sounds like one of those ideas that are good on paper, but flirt with disaster in real life applications!

 

You hit the nail right on the head!!

 

Volvo is not the only one to do this. Many of mfr. do this. In fact I think my Toyota has this. Bringing the tranny up to temp. faster probably helps with gas mileage in the colder regions.