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2004Mazda6 overheated question

Hi, all;

Car: 2004 Mazda6 V6 auto with 220,000 miles on it. Yesterday, in rush hour traffic on the highway, saw a puff of white smoke from under the hood. Tried to get over to the right- by the time I got over, I’d passed the last exist before the Baltimore Harbor had to keep driving till I could find a safe spot to pull over. Temperature gauge spiked, so I turned on the heat, on full- and got cold air coming out. Temp gauge then dropped to cold, and all dashboard warning lights lit up. Small antifreeze puddle under car…had it towed home. Truck driver was able to get it started long enough to roll it off the truck into parking area.

Any thoughts? Any idea how badly I damaged engine by continuing to drive the 2 miles through tunnel?

Possibly Toasted a light golden brown… If it survived I would be surprised. Hard to say from here…Only one way to find out. Replace the thermostat, refill and burp the radiator and see whatcha get. If it survived that would be great you never know. Todays engines do not tolerate an overheat like the days of Old Detroit Iron did…so you just have to see what happens. Maybe you will be ok?

There will be sufficient evidence if it did not survive. If it did not…you need a new head gasket and to mill the cylinder head flat again. Which also begets a new timing belt, water pump and all that stuff because it will be apart.


Difficult to say from here, at least a look under the hood is needed but my guess based on mileage is a head gasket. At that miles, your best option might be a new or used engine vs a new car.

I’d fill it up with water when it is cold, then try to start it. If it warms up to normal temperature and holds there, drive it for a few miles to see if it holds temp. If you have blown the head gasket, it will overheat pretty quickly so don’t go too far from home while testing.

Thanks, all. Kinda what I thought. Will give that a try. Car may be sitting for a week or so before I can do so. Fortunately was my backup car…

First priority, find the source of coolant leak. My guess, on a 2004, the radiator has sprung a leak. You did the right thing to put on the heater to max, that probably helped you on the amount of damage that was done. It sounds like you may have developed a large loss of coolant. That would explain why no heat from the heater, and the dashboard coolant temp gauge dropping. No worries. If your alternatives in a situation like that are stopping in a an unsafe and dangerous place, or staying safe but continue to drive and risk damaging the engine, what you did, the latter, is clearly the better of the two.

I’d run a dry and wet compression test. Given the age and miles of the car along with the severe overheating incident the piston rings could be wiped out.
The last thing you would want to do is spend money on an engine that may never run right again and smoke like a prairie fire.

All good suggestions. I just wanted to compliment you on placing safety first at the risk of your engine. Some people would create a massive pileup rather than risk a damaged engine, but you definitely had your priorities in order. Save lives first, then save engines.

Sincere best.

Thanks, all. Car is at the shop now. Apparently lost a coolant line (hose), and the water pump itself was getting “iffy”. Mech. said that he’s pressure tested the car, as well as road tested it, and it seems to be running ok. But at 220,000 miles, I think this’ll be a short distance trip car from now on.