Hi all,

2.8L V6 w/ 248k miles.
TB bypass done, heater core always on full blast (I removed the vacuum valve and plugged in directly), couple new radiators over the years, 180 stat installed.

Recently (over the past 6 months), I've been losing coolant somewhere. I can't for the life of me find it. I thought for a while that it was from the coolant recovery bottle or line, but that isn't it.

Last week (Sunday) I flushed it and put in new 50/50 (yellow bottle Prestone Extended Life) with distilled water.

i drive the car 20 miles to work and 20 miles back, 15 of it is on the freeway at 65-75mph.

This morning (after having driven 200 miles last week and sitting in the driveway over the weekend), I overheated. I had noticed that the temp had been creeping up last week on thursday and friday (it usually stays stuck on 170-180 (instrument panel gauge), on the freeway. It was at about 200, so I figured I'd check the level over the weeked. Well didn't get around to it.

Anyhoo it took almost a whole gallon this morning.

I don't have any in the crankcase, oils pretty fresh and it looks fine - I don't have any odor of coolant in the engine compartment, don't have any visible leaks or puddles under the car.

Where could the mystery coolant be going?

 

is the carpet on the passenger side car under the dash damp?
do u have a cooling system presure tester?

 

If you go to Autozone they rent you a system pressure tester that screws on to the top of your radiator. You get your money back when you return the tester.
Does your exhuast smell sweet or is it burning white smoke at all?

 

check all your plugs.

 

Passenger carpet under the dash is bone dry. No smell of coolant in that location. I caught the tiniest whiff of sweet coolant under the hood in the rear passenger side, where the AC accumulator is located, maybe I'm just hypersensitive and hoping thats all it is.

My exhaust smells normal, no coolant seems to be getting burned, it smells slightly rich, as it always has.

On the bright side I found a vacuum leak thats been plaguing me for weeks too! It was the hard line that used to go to the heater core vacuum switch. The exhaust had melted my plug and half the line.

Well, it has to be going somewhere right? Perhaps that whiff I caught from the heater core area is the tiniest pinhole imaginable and its only letting steam out. Could that account for a quart of coolant loss in 40 miles of driving?



I dont' have a coolant system pressure tester, just the valve style cap that lets a woosh of coolant into the recovery bottle if I flip it up while she's hot.

I suppose the heater core being that its on its own little circuit is not going to show up if I test the system. I think my next course should be to bypass the heater core. At least it would eliminate that as a potential problem right?

Thanks everyone for the help!

 

If you had a heater core leak, you'd have coolant on the floor everytime you used the heater.

 

Or, like I had, coolant mist blowing in my face when I turned my heater on. About 10 seconds of that and my window fogged up and I had to pull over. Anyways..
Get the pressure tester from Auto Zone(its free), it should help. You do the test when the car is running also, so you can turn the heater on then and see what happens.
Do you have bubbles in your overfill tank at idle? What about when you give her a nice high rev while in park?