Here is the deal. I live in northern Wisconsin. I have a 2004 MCS MC-40 edition with EVERY JCW mod there is. The car is my Sunday driver. It has never seen a drop of salt. Needless to say it spend quite a bit of time inside to the tune of 5 to 6 months. Anyway, the tundra is finally thawing and I decided to back the car out of the garage and fire it up. The battery was dead but after a quick recharge it seemed to start fine. I let it sit and run for about 10 to 15 min at idle while I cleaned the garage and then pulled the car in. I checked the temp gauge and it was in the middle of the dial. I blipped the throttle a couple times never above 3K revs. I then let it idle for about 5 more min. At this point I noticed steam pouring out of the engine bay. I immediately turned the car off and found that coolant was gushing out from the expansion tank. I checked the temp gauge again and it was still normal. Any thoughts?

P.S. The ambient temp was about 50 F.

 

Cracked expansion tank?
With temp temp gauge at normal before and after, that's the only thing I can think of.

 

Already thought of that. But the hood was up at the time and I clearly saw fluid coming out of the cap...

 

One...kinda bad reason the coolant could be overflowing...barring ofcourse the chance you have found a way to get coolant to multiply....a failing headgasket that is allowing combustion gasses into the coolant system...adding compresses gasses...and when this happens, something must escape....so coolant is vented....
I hope I am wrong....but of all the ways it could fail...this is the least dammaging as long as the coolant does not get into the oil. Check you oil too to be safe.....like I said, I hope I am wrong, but sometimes letting a car sit is harder on it than driving it.
Good Luck!!

 

What guage are you reading the water temp from extactly ? Is it a real temp gauge with numbers or the factory one on dash with hash marks.

Did you hear the high speed fan kick in at all ? You will know it when it does, sorta sounds like a garage shop vac. It's pretty loud. The cooling fan should come on automatically too when you put the heat a/c on.

If not, then check the fuse for it. Could be you blew a fuse when jump starting it. If the fuse is ok and the fan does not come on, then maybe the whole radiator fan assembly needs to be replaced. TYC brand fan housings with a lifetime warranty can be purchased on eBay for about 90 dollars and free shipping. I had to replace mine few months back. Had overheating issues when at idle.

 

Stuck thermostat? Hold your hand on the radiator hose to see if antifreeze eventually flows through. Yes, see if the cooling fan kicks in, too.

A blown head gasket is certainly a possibility. If steam is coming through the coolant expansion tank, then that is a good sign antifreeze is not backing into the combustion chamber. You don't want to attempt to compress water; that can cause bent or broken connecting rods. I would theorize a small amount will backflow into it. Take out each plug and look inside with a flashlight to confirm.

 

Thanks everyone! Turned out way better than expected! When I took it to the dealer in Minneapolis last summer (right before I put it away) they not only forgot to put on the gasket on the oil filter they apparently screwed on the coolant tank cap improperly and not on the threads. Thus coolant could escape even though it looked like it was screwed on. Guess Im not going back there!

 

Good to hear!! Not that it was avoidable...but that it was all caught before the oil leaked out, etc!!
I've found that mini centric independant shops much better to deal with than all but the best dealers....and far cheaper than all!!
Sounds like that dealer let the new kid work on you car...I hope they refunded your money for the service, and gave you a gift car to use for some stuff!! If they did not...write a letter...they should IMO.

 

Yes, glad to hear it was a minor issue that required no repairs.