I'm already expecting bad, but throwing this out in case it might be something less really bad. Car is 2004 MCS about 105k miles. Few weeks ago my expansion tank blew up. Replaced it with an aluminum tank, seemed to work fine but no heat. Poking around the forums I figured it was that I needed to burp the system since this was the first time I've even had to add coolant to the system (had the Mini for about 15 months now). Hasn't really been that cold so I drove the car with no heat for a few weeks and the engine temp has not run hot at all.....until a couple weeks ago. Ran a little hot while sitting in traffic. Checked and it was low on coolant, needed to add about a quart+. Ever since the overflow tank replacement, I can smell coolant every time I drive the car and shut it off. And since the run hot incident, I've been checking about every 3rd day and have needed to add about a half a quart of coolant. Figured (or maybe hoping) it was some uneven cooling going on so i decided I needed to take care of burping the system this past weekend. I couldn't seem to get it bled. I tried to pressure bleed through the upper coolant bleed hole. Numerous attempts and seemingly after I thought it was, let it sit and there would be air in the system again. Haven't seen any white smoke, no coolant in the oil (small miracles), and no obvious leaks. Just the smell and the coolant disappearing. My next step is to get the coolant tested to see if there is exhaust gas in it. Thoughts?

Assuming the worst, I've contemplated buying a replacement engine out of a yard to rebuild, versus tearing into this one and replacing the head gasket. Or swap in the replacement and rebuild mine, so I have more time. All told I'd prefer not having to do either of those......

 

Slow down, there are tons of things to check before you start pulling your engine out. You're not getting any smoke, and I guess you've checked to see if you have any oil in your coolant, or coolant in the oil?

Check your thermostat housing, that's where I would begin. Change those parts out, common problem...

 

Yes, no coolant in the oil and while I was attempting to burp the system this weekend, I drained the coolant and started fresh. I didn't notice any oil slick in the pan. I'll check the thermostat housing, tonight but I'm assuming if that was it, wouldn't it be visible either burning off or puddle? Thanks for the reply.

 

Areas for coolant leaks are the heater, the oil filter housing, the T-Stat and the water pump. Do not discount all the other coolant tees and couplings on a 13 year old car bas well. The biggest question I have is how do you know you filled the system back up correctly the first time? When I do work on my car I use a wet vac to remove the coolant, I can get about 95% of the volume out of the radiator system in this manner. I can measure how much I took out so I know how much to put back, BUT, as you are smelling glycol it appears have a minor leak somewhere.

The problem with the Mini is that you could have a small leak around the tstat/water pump and not really notice drips on the ground. If you are careful you can move the plastic shroud between the radiator and the supercharger enough so that you could put some paper towel down below the BPV. If the water pump is leaking, the towels would get damp. The t-stat housing can be seen by removing the air box and the hoses going to the throttle body.