I answered on the f-body forum go there and read my reply but I suspect it is ATF.

 

I drained the coolant tonight and filled it with plain water so I can look at it tomorrow without it being colored by antifreeze. Tomorrow I'll probably flush it out and fill it properly if I don't find oil in it. Or even if I do. Either way, I don't want just plain water in there for any period of time.
Why do you think it is ATF rather than oil? Since I don't have water in either the oil or tranny fluid, that doesn't tell me anything. I'm just glad that's the case, since it should mean that there is no internal damage resulting from this. The engine hasn't been overheating, so I guess that's good. I really can't understand how a fluid could get into the coolant without any coolant getting into the source of the leak. Scratching my head over that one.

 

Maybe the tanks on the rad. are leaking allowing Oil or Trans fluid to mix with coolant.

What kinda car is it?

If coolant is mixing with oil or trans fluid your tranny or engine will not be happy!

 

Originally posted by gasnmyveins:
...Why do you think it is ATF rather than oil? Since I don't have water in either the oil or tranny fluid, that doesn't tell me anything. I'm just glad that's the case, since it should mean that there is no internal damage resulting from this. The engine hasn't been overheating, so I guess that's good. I really can't understand how a fluid could get into the coolant without any coolant getting into the source of the leak. Scratching my head over that one.

Its not uncommon for oil in coolant in medium/heavy diesel engines. Anything with a fluid to fluid cooler like the trans cooler in the radiator tank is susceptible to internal leaks.
When the engine is running oil pressure is greater than coolant pressure so if there is an internal leak at the cooler, oil goes in the cooling system. If the leak gets bad enough to leak at low pressures then you can have cross contamination both ways with engine on then off.

Probably looking at replacing the radiator whether ATF or engine oil, even if you have engine oil cooler in the radiator tank too. I would also flush the trans with fresh ATF, antifreeze can delaminate the transmission clutch linings.

 

Years ago now I dismissed a little brown crud in the fill tank as just slime from old coolant, that is until one day when the in radiator tranny cooler REALLY went and overfilled my cooling system with ATF puking it out of the pressure cap on the fill tank.
I didn't have an in radiator engine oil cooler but if you do that would be a prime suspect as well. Either way I would be looking at replacing the radiator, MUCH cheaper than coolant in the engine or tranny should this get worse.

 

Well, I've drained it once and got some more brown water for my efforts. Then I remembered that when I was running the car and running new water through it to try to get it all out, I didn't have the heater going. I drained it again tonight with the heater running and filled it with water and radiator flush cleaner. It says to run it for 3 to 6 hours and then flush it again. For me, that's several days just to hit 3 hours.
When I talked with my mechanic, he said the same things you guys said about it maybe being the radiator. My car has the oil cooler and the tranny cooler. I see a cooler mounted in front of the radiator. Is that the tranny cooler? Is the oil cooler inside the radiator? If it is, I could bypass it and see if the problem stops. The oil cooler isn't critical. If that takes care of it, I can either just leave it bypassed or put a separate cooler next to the tranny cooler and cap off the entry and exit holes in the radiator oil cooler. If it's the tranny cooler line in the radiator, I guess I'm hosed and will have to buy a new radiator.
I'll get back to you in a few days. Thanks for all the help.

 

If the rad is toast just get a new one. They are not much $$

Cooler on the right side is the trans (pass), Cooler on the left side (drivers) is the oil if its a 9c1.

 

It's a roadmaster. I'll go look tomorrow to see what's under there.

 

It's a roadmaster. I'll go look tomorrow to see what's under there.

 

What should I expect to pay for a radiator? If I need one, I'll probably get a pretty good one, since I hope to mod the snot out of this at some point and don't want to have to buy another rad later because I was too foolish to do it now. Maybe I'll call Summit and Jegs tomorrow.

 

So did you get it fixed? I have the same problem. http://impalassforum.com/noncgi/ultimatebb.php?ubb=get_topic;f=33;t=010686#000004