My car has a coolant issue. If I fill the expansion tank and let the car warm up, it will at some point empty coolant via the expansion tank’s overflow. There are no other fluids on the ground except for two spots that seems to be normal condensation. Once it discharges the coolant, the “Low Coolant” light comes on. When the car is warm, you can smell coolant.

For the coolant to be discharged through the expansion tank’s overflow to me is an indication that there is air trapped in the system. If that is true, how long should I have to top up the expansion tank until all the air is out, or is there a way to bleed the system? (On my old BMW there was a valve on the thermostat housing to get all the air out.)

The water pump and the thermostat have been replaced at the dealer in the last month, as well as tensioners, timing chains, etc. The dealer performed a pressure test, and could not find anything so far. I assume a pressure test includes the expansion tank. Could it be the expansion tank cap?

Any ideas or thoughts?

 

It could be the cap, but also check the atmospheric Recovery Bottle (item 11) hidden in the the front fender behind the wheel well liner:



This is where the excess coolant from the Expansion Tank (item 1) goes when the engine is up to temperature. The coolant is drawn back into the Expansion Tank as the engine cools.

Apart from the Atmospheric Recovery Bottle cap or pipes becoming detached, it can also get a build-up of slime or sediment in the bottom preventing it from functioning properly.

 

Im having the same issue with my vehicle. At first I wasnt tightening the cap on the overflow resovoir completely and I could see dried antifreeze on top afterwards when the car was off. Now that I am completlely tightening it, it is still runs low after about 150 miles. Ive looked under the car and havent found it yet but I can smell antifreeze when the car is on. Look for dried coolant along all your hoses and or waterpump. Im gonna keep looking for my leak and let you know what I find..

 

Carefully check around the base of the thermostat tower and the plastic pipe across the front of the engine.
After that it gets more difficult, because the heater hoses are likely culprits. You can rent or borrow a pressure tester at many auto parts stores, and that is the best way to locate leaks most of the time.

 

Check the hoses to the expansion tank as well. One of the original clamps on mine was no longer tight and once warm & under pressure would leak. It was falling onto the engine or maybe the headers and evaporating so no drips when stopped. It did however smell of coolant. Trimmed 1/4" off the hose and put on a new clamp, problem solved.

The expansion tank itself is known to crack and begin to leak. This also leads to the dreaded Low Coolant message.

 

All the usual suspects have been identified in the thread.

If you've checked and eliminated them, my next thought would be faulty Thermostat. Just because it's been replaced doesn't mean you can assume it's OK.

Graham

 

For months I could smell antifreeze wafting through the air when I stopped, and yet I never had a drop on the driveway. But about once a month, I'd have to add about a cup's worth of coolant as the warning would come on. It obviously wasn't a bad leak but we found it, finally, in the heater hoses' connectors. Pain in the *** to change, but solved the problem. 2nd choice would be thermostat, as stated above, just 'cause it's new doesn't necessarily mean it works.

 

Well, it has been confirmed by two different places. Head gaskets needs to be replaced.

After spending a lot of money two months back, it seems I will be spending lots more money.

This was not the answer I was hoping for, but it is was it is..

 

Ouch! Good luck with the repair, and let us know what the final cost turns out to be....

Who will do the new head gaskets for you?

 

Personally I would get a THIRD opinion. If you are loosing that much coolant you should see----- 1. White exhaust,smell the exhaust at idle.
2.CEL cooling the 02 sensors

Before I'd pull the heads I WOULD run the the engine until it;s fully pressurized let it sit (over night) next morning pull the plugs to see if they are wet, if they ARE then go ahead with the gaskets, if NOT, don't and look else where, seems like extra labor but could save needless gasket replacement and still have the problem and they could say anything but not give your money back or credit. You can pull the front three without removing the intake, if it;s the rear (firewall side)bank removing the plenum isn't that hard and you can reuse the o-rings if they were new. Just a thought
Good luck!

 

Sorry for the rant I didn't see it was resolved LOL