Well I was driving home from school somewhat aggressively (not flooring it the whole way but having some fun) and when I reached a stop sign I noticed some white smoke coming form what looked like my hood. At first, I thought it was the wind blowing the exhaust forward, and kept driving, but at the next stop the wind was coming from the opposite direction and I still saw smoke. I was really worried but the road had no place to pull off and I was about a mile from home anyways, so I limped it there. I also should mention that the temp gauge was right in the middle the whole ride, so it wasn't like the engine overheated. When I got out, the first thing I noticed was the smell. It was so intense, and so obviously coolant, "oh ****" was all I could think of. Then I noticed that yellowish-green fluid was covering almost all of my bumper in front of the grill. I popped the hood and a huge cloud of foul white smoke went right to my eyes, and when it cleared I could see that almost every inch of my engine bay had coolant on it, which especially sucked because I had detailed the engine bay last week. I couldn't find any obvious leaks/cracks/damage on anything, the only thing that stuck out to me was the overflow cap was not very tight and although my bumper was covered in fluid, the front face of my radiator was totally dry.

I called up my buddy at a local Tuffy and he told me it should be fine to fill up the coolant and drive down to his shop, so, well, that's what I did. A few hours later I call him up and he tells me that he can't find any kind of leaks or breaks anywhere and, besides the engine smelling like burnt coolant, everything is fine and working correctly. He also said that he suspects the water pump, but he can't really check for that without taking everything apart. When I picked the car back up, I drove around for 2 hours with a good mix of slow and aggressive driving, trying to see if it would happen again, and it didn't.

So this is the problem I am confronted with. I plan on driving around a lot out in the middle of Arizona where there are very few people, much less people I can call to tow my overheated car. I don't just want to let this go and hope it doesn't happen again, although I already plan on keeping a jug of coolant in the back. It would really suck to get stuck 150 miles outside of Flagstaff in the middle of the night on a road that doesn't even have an official name with only a bottle of water and a dieing cell phone, so is there any way I can get a more permanent fix for this? Like a new overflow and cap that are better secured? Or even just your thoughts on the whole incident? Thanks for any help, as always.

 

I would have the cooling system pressure tested and if it holds pressure and the visual inspection is ok then i would consider it OK. If you suspect the cap is suspect, replace for peace of mind and enjoy driving your car. That is about all you can do.

 

I would also check the oil to see if you have water in it.

 

Yes, they pressure tested it and checked the oil (for an unrelated issue) and both were fine.

 

On a different car... I had the thermostat get stuck open, causing coolant to purge through the overflow tank- causing it to empty almost all of the coolant on the front of the engine compartment.

Thermostat is cheap and easy to replace. Just a thought.

 

Similar thing happened to me, but to a lesser degree. My coolant cap must have gotten "cross-treaded" at some point during my supercharger installation and it began to leak all over the coolant tank. It happened no matter how many times I took it off, and firmly reseated it. Bought a replacement cap for $5, and problem solved.

 

Composite thermostat housing is probably cracked... very common on the 4.0

 

He said he checked the housing and it appeared fine. I don't know about the coolant cap being cross-threaded, but I was thinking of getting a moroso tank and an aftermarket cap that is supposed to handle 19psi (supposedly more then stock, anyone have numbers?).

 

The pressure test should identify any leak from the composite t-stat housing. When I read the OP's post, the housing was my first thought.

 

I would replace the overflow cap. Cheapest option and on my 06 I ended up replacing it twice...usually because of spirited driving. The OEM piece sucks, but for 15 bucks or so its good piece of mind and it was the fix both times for exactly the same thing.