The Phantom strikes again

[Kristuphir]

OK, I've detailed a phantom cooling issue that I've been dealing with over the past month here: http://www.bimmer.info/forum/showthread.php?t=20287

While chasing this bugger down, I have replaced the thermostat (with hole drilled at 12 o'clock), the water pump, a leaky hose, and the radiator cap. The radiator looks newish. For that matter, the Tstat was new according to the PO, and the water pump didn't look or feel bad either (hmm...was PO chasing this same problem?). I have also drained the crappy green coolant, flushed the system, and refilled with BMW blue.

I have bled, and bled, and bled, using a variety of the methods detailed all over this site.

There's no oil in the water, and no water in the oil. The car will run for days or weeks without the needle budging from just under halfway. Then, pop, it'll start flying up. I've done more roadside bleedings with my trusty "emergency" 8mm wrench than I care to think about; every time I do that, the needle drops to halfway in seconds. I took an 800-mile trip with no issues whatsoever. Then I came back and had the problem again.

Most of the parts replacements were this past weekend as a result of that.

It's run fine since Saturday, but tonight it overheated just as I was rounding the corner home. I turned on the heater full blast just to see what would happen, a first in this situation - it blew cold and smelled strongly of coolant, which it never has before (either of those two things). I shut it off and wrestled it to the curb, and popped the hood. The expansion tank had coolant on the outside, which had leaked down among the myriad hoses clustered around the heater valves - another first.

I shut the hood and went inside. It's been a shitty day to begin with.

What's going on? Have I gone and screwed up the heater core, too? I'm tired of driving around with my eyes on the temp gauge instead of the road.

[Rustam]

OK, I've detailed a phantom cooling issue that I've been dealing with over the past month here: http://www.bimmer.info/forum/showthread.php?t=20287

While chasing this bugger down, I have replaced the thermostat (with hole drilled at 12 o'clock), the water pump, a leaky hose, and the radiator cap. The radiator looks newish. For that matter, the Tstat was new according to the PO, and the water pump didn't look or feel bad either (hmm...was PO chasing this same problem?). I have also drained the crappy green coolant, flushed the system, and refilled with BMW blue.

I have bled, and bled, and bled, using a variety of the methods detailed all over this site.

There's no oil in the water, and no water in the oil. The car will run for days or weeks without the needle budging from just under halfway. Then, pop, it'll start flying up. I've done more roadside bleedings with my trusty "emergency" 8mm wrench than I care to think about; every time I do that, the needle drops to halfway in seconds. I took an 800-mile trip with no issues whatsoever. Then I came back and had the problem again.

Most of the parts replacements were this past weekend as a result of that.

It's run fine since Saturday, but tonight it overheated just as I was rounding the corner home. I turned on the heater full blast just to see what would happen, a first in this situation - it blew cold and smelled strongly of coolant, which it never has before (either of those two things). I shut it off and wrestled it to the curb, and popped the hood. The expansion tank had coolant on the outside, which had leaked down among the myriad hoses clustered around the heater valves - another first.

I shut the hood and went inside. It's been a shitty day to begin with.

What's going on? Have I gone and screwed up the heater core, too? I'm tired of driving around with my eyes on the temp gauge instead of the road.

I recall once I bled and bled and bled... And it ran fine till once the needle went too far. How exactly do you fill the coolant?

1-open the 8mm bolt
2-fill till coolant runs out through the orifice under the bolt
3-close the bolt
4-pour the rest of the needed amount of coolant into the system
5-pour a half a cup more to get a margin for bleeding
6-start the car and do the bleeding procedure.

[632 Regal]

K, i think the heatercore or connections have a leak and when the car is off and cooling its sucking air into the system giving you an air pocket.

makes sence to me at least.

[Kristuphir]

Yep, that's exactly the way I've done it...to a T.

I saw in another thread that someone had problems from the O-ring on the Tstat being installed on the block side rather than the housing side of the stat. The problems were a little different than mine, but similar enough. I'll try switching the ring around and see if that helps. I wish this were at least more predictable so I'd know if I fixed it or not...

[Kristuphir]

K, i think the heatercore or connections have a leak and when the car is off and cooling its sucking air into the system giving you an air pocket.

makes sence to me at least.

Hmm. You take that back! Take it back!

I was afraid of opinions like this....