2003 impala trans fluid mixing with the coolant in radiator

[bobbyboy-g]

does anyone know what this problem might be....my 2003 impala overheated 7 days ago...i checked the radiator and found trans fluid mixed with the coolant....the mixture was coming out of the res tank...okay i thought i will by a new radiator, since it seemed the logical thing to do...a new radiator was put in this weekend, system was flushed new coolant etc., trans filter changed new fluid etc...i have driven it about 25 miles since and the car starts overheating again, i get home and check the radiator and the same thing is hapenning again the fluid is mixing...i am at a lost now as i dont see how this can be...please help !!!!!!

[maxwedge]

Welcome to AF. You probably did not get all the tf out of the cooling system, some residual is always in the block, might try and have it done on a power flush machine many garages and dealers have them, tell them what happened though.

[bobbyboy-g]

hey max, thanks for the welcome and quick post....i will do exactly what you recommend.....i opened the radiator plug and drained it into a bucket and the mixture was a LITTLE oily only and not as bad as i had thought, but enough to overheat it, air conditioner was on also as its a hot day out here in california...thanks again.....BOBBYBOY-G.......

[silicon212]

Did you find out what caused it to overheat originally? The thermostat is a common failure point, check that to see if it sticks.

[bobbyboy-g]

hey silicon212, i just assumed it was something inside the radiator that caused the fluid to get in,and that in turn caused it to overheat being that the fluid was extremely thick...but i think its a good idea to check the thermostat..anyway of checking that without taking it off the car ? thanks for your reply...bobbyboy-g

[tractorboy]

also on the block of the 2oo3 , on the la1 , 3.4L there is a bolt on the front of the engine block, i think up to the right of the oil filter. this bolt when removed will drain the engine block. also do not forget to bleed off air in the cooling system with the bleeders on the engine castings for hoses, follow manufacturers instructions. Also FYI , starting with the 2oo3 you actually can not overheat the engine in the sense of warped heads and such , i am told. With no coolant the PCM puts the car in limp mode.

[bobbyboy-g]

that sounds like another good thing to do before taking it to get power flushed....and yea thats true about the car going limp...when the car started to blow steam and the red temperature light came on, the car started to lose power, it went down to only about 20 miles an hour, but i was on my block by then THANK GOD.....thanks bobbyboy-g

[tractorboy]

also you will notice you do not have a low coolant sensor like the 2000 - 2002 impalas have. There is something too in the owners manual about driving the car w/o coolant too. I do not know how far you can drive the Impala, when i first Heard about this it was on a Cadillac. In the article it said the car could be driven 125 miles.

[wtousand]

In reference to: "Also FYI , starting with the 2oo3 you actually can not overheat the engine in the sense of warped heads and such , i am told. With no coolant the PCM puts the car in limp mode.", I think it started earlier. There is no mileage listed for overheat drive mode for the 2000 Impala, but...

On page 5-10 of the 2000 Impala owners manual, of my wifes 2000 3.4L Impala, there is a paragraph stating;
"OVERHEATED ENGINE PROTECTION OPERATING MODE

This emergency operating mode allows your vehicle to be driven to a safe place in an emergency situation. Should an overheat engine condition exist, an overheat protection mode which alternates firing groups of cylinders helps prevent engine damage. In this mode, you will notice a significant loss in power and engine performance. The low coolant light may come on and the temperature gage will indicate an overheat condition exists. Towing a trailer in the overheat protection mode should be avoided."

On page 5-11 there is a box:
"NOTICE
If the engine catches fire because you keep driving with no coolant, your vehicle can be badly damaged. The costly repairs would not be covered by your warrantee. See 'Overheated Engine Protection Mode' in the index". Another Notice box states that the "oil will be severely degraded" (I assume overheat breakdown) and need changing.

Also, in regard to oil in the coolant, we have this problem at the moment. Our first clue to any problem was the Low Coolant Sensor came on and the car may have been low on coolant. The reason I say may, is because my wife filled the reservoir until topped off and then filled it again until it flowed out the overflow when the Low Coolant light did not go out. When I checked the actual radiator, it was full to within 2-3 inches of the top of the filler neck and the now intermittant light finally never went out although the radiator Low Coolant Sensor is well below this level. When I finally dipped a drinking straw into a cool radiator, it came out with what I believe was engine oil on it. Placing some on a napkin and burning it acted like an oil lamp wick as it sputter-burned the watery "oil". Another napkin dipped in pure Dex-Cool burned all around the wet and went out. So the sludge wasn't anti-freeze.

I think the car is sucking engine oil from, perhaps, the intake gasket area. I believe I saw that on this forum somewhere but haven't found the reference again yet. I think there is a possibility of cleaning the Sensor after all this is over so that I may avoid spending $50+ for a new one. I've been told that a local GM dealer just recommends unplugging it to get rid of the annoying error light, if the replacement price is a problem.

Since the intake gasket is so notorious, and the car has 80k on it, we are taking it in for repair, even though we haven't proved the gasket is the leak. I found a decent mechanic to do the work for an estimated $350. Last time he did work for me, it came in 25% lower than the estimate, if you want to believe that in this day and age.

As a note of interest, my brother took his wifes mystery-leak Pontiac '95 Grand Am (3.1 liter) in for first a water pump, then intake gasket, and finally timing cover gasket. It still leaked a tiny bit somewhere after $1500 until he put in stop-leak.

My wife also has a Corvette and the specific factory Helm Overhaul Manuel recommends stopleak tablets as a matter of course with all coolant change-outs. So I have some on hand.

[richtazz]

I would bet that's engine oil in the coolant, and the intake issue mentioned above is your culprit. You are at the mileage where the intakes start to go. I just changed another one on a 99 Monte, and like all of them, the outboard intake bolts were loose (GM doesn't use thread-lock from the factory). This situation allows the intake to move, cracking the plastic/rubber factory gasket at the coolant transfer passeges, leading to the problem. Make sure your mechanic uses the updated metal/rubber gaskets, not the plastic/rubber oem style.