Bubbling noise under the dash / in the cooling system

I have a 1998 ES 300 with 116k miles. I bought it used about 6 months and 6k miles ago. Couple of months ago noticed that there is a bubbling sound, (similar to blowing bubbles in a glass of water with a straw)comes when I start the car.

And as the weather has cooled down recently (Pittsburgh, PA) I have noticed that there seems to be excessive white smoke from my car while idling, I know its an older car but it seems that the smoke is more than normal.

Are the two issues linked? Is there leak in the cooling system allowing air in?

Are you losing coolant from the reservoir and/or the radiator? Remember to remove the radiator cap only when the engine is stone cold.

From what you describe, I suspect you have a leaking head gasket (you have two on the V6). The mechanic can use a emissions sniffer to see if there are combustion gases in the air above the upper radiator tank.

Good luck on this. Let us know the outcome.

I can only suppy some more facts about what happens when exhaust gases come in contact with coolant, the car overheats faster than any other failure would cause, your car is not overheating.

The gurguling you hear in the dash could be caused by AC pressures equalizing, or it could be air(not exhaust gases) in the cooling system.

The increased “white smoke” when ambient temps. are lower could simply be condensation.

Is there a overheating event that you have forgotten to list?

Simple test kits exist that can verify the presence of HC (Hydracarbons)in the coolant.

No over heasting issues…and I have taken it to a 800 mile trip with no issues.

I realize that the lower ambient temps cause the white smoke to increase in all cars but mine seems more than usual, perhaps just my imagination! I hope!!

To ‘remove’ the air I’ll check the coolant level and top it off, but can I probably can’t mix coolants and I don’t which brand is in car right now to top it off with. Should I drain and refill?

I’ll see if I can find the test kits you mentioned.


You COULD have a leaking head gasket, but my guess is that the coolant is a little low and there is air in the system. When it is low you can hear it gurggling into the heater core. I don’t think you need to worry about the brand of antifreeze you add. You shouldn’t mix Dexcool with regular antifreeze tho.

How do figure out that Dexcool isn’t already in there??

I’ll take it to my trusted area mechanic and see if he has any ideas.

take it to my trusted area mechanic Good idea, but I think Dexcool is yellowish orange.