[WMX267]

Hello there!

I'll go straight.

Replaced the water pump because of a worn out shaft. After installation, I noticed that the temp would drop a little and then go back to normal. Ignored it for a while and then heard the thumping noise. At one point, the upper hose was pumping (as in collapsing and expanding) even after switching the engine off. I decided to change the thermostat after that as I thought the vacuum was trying to such h20, but the old tstat wasn't opening.

Installed it and still the same noise and dropping of temperature, but now, it would seem like it would want to overheat, and then the tstat would open (theoretically), so it would go all the way down, and slowly come back to normal.

Tried bleeding/burping the system already (I hope I did it right), but haven't gotten better results. Do I just let the engine idle when burping or is it fine to have it @ 2000rpm?

I got squirted with coolant when it shot out. This is the tstat opening right?

I understand a worse case scenario would be gaskets. Just on the heads? or would intake / exhaust gaskets also cause this?

I can't exactly say that it's related to the airconditioning. Could it? How? But somehow I think it's aggravated when the compressor is on load. Otherwise, would there still be a connection? I refilled my A/C refrigerant prior to this, if that matters.

I'll try completely flushing the system when it gets warmer (Calgary), but other than this, what could be causing it?

Could be the coolant sending unit. Testing is decrease in ohms with rise in temp right? Now it that the one that goes to the dash? And there's another one going to the OBD right? Or could there be just one?

I know those are a lot of questions. On top of fixing it, I want to know how the system works or what's causing it not to work and how. Thanks in advance.

I would want to still have it when I say, "Oh that's the problem!"

1997 Ford Explorer 4.0 V6 OHV