2006 MCS - Stock

Background:

Two months ago, I noticed high speed fan running more than usual, then car began overheating. Mildly at first, but then when stuck in traffic temp gauge pegged left and idiot light came on. My g/f was driving and drove for another mile or so with the light on (doh!).

Checked low speed fan--was not working. Wired in external resistor and voila, fan started working; however, car still running hot. Checked coolant--was low, topped up and everything fine.

Fast forward two months and ~1k miles, and while changing oil, noticed large amount of coolant residue all over engine block/oil pan beneath water pump.

I checked the coolant level and it seems fine, suggesting no coolant has leaked since I fixed the low speed fan and topped up.

Now the question is...where did the coolant come from and why is it not still leaking (or is it?) I know there is a weap hole for the water pump, so maybe the coolant boiled over and came from there when the car overheated (light came on)? Also, the O-ring between the water pump and the block could have have blown, but wouldn't the leak get worse, not better, over time? I'm somewhat perplexed.

Any thoughts are welcome.

Thanks,
Mike

 

Maybe the thermostat gasket.

Also check the coolant tank, they are known to split at the seams where you can see, and where you can't see easily at the bottom.

 

Been there, done that--mine was the thermostat gasket.

Shine a flashlight on coolant reservoir, look all around it, if you don't see any crystallized residue, you can rule that out.

 

Thanks or the suggestions guys. I changed the thermostat (and gasket), but didn't see any signs of coolant from the housing. I also don't see any coolant residue around the expansion tank (I have the newer style one).

All of the coolant residue I see is on the front of the block under the supercharger/water pump and the front of the oil pan.

 

You're getting that since changing the thermostat gasket?

If so, you're going to have to follow all the lines, and check the radiator. If it's still leaking, unfortunately I'd bet radiator rather than lines, they are prone to it too.

 

Actually, since fixing the low-speed fan resistor and topping up the coolant, there doesn't appear to be any leaks. However, I'm confused as to where the leak was coming from originally.

One thought is when the car overheated, the coolant literally boiled over and leaked from the water pump weep hole, but I'm not sure this is physically possible as I don't have a water pump handy to inspect.

-Mike

 

If it's not leaking, I'll betcha it was the gasket then. The thermostat is more toward the left front of the engine bay--I had most of the coolant pooling underneath the car toward the right front. There is a bunch of wires and pieces for the coolant to drip onto then follow. What happens is the coolant follows lines and whatever it drips onto and can wind up damn near anywhere, even on the opposite side of the engine bay.