Overheating after replacing all the cooling system parts

[bichmgnt]

I put in a new thermostat, new fan clutch, new water pump, new radiator and all new hoses. There isn't much more I can replace. Heater runs cold as well. It almost seems as if there is a blockage somewhere but everything I looked at seemed nice and clean with no evidence of buildup. What's weird is that when I start to drive the temp goes down but not all the way to center and heat starts to come out of the heater. But if I stop the temp goes up and the heater goes cold. Overheating is a recent problem but it isn't the reason I did all this work. The radiator broke and I used it as an opportunity to replace all these items (along with timing belt and fuel lines) since it was all open anyway, and the overheating seems to be worse now than before. Maybe the thermostat opened sooner? Heater worked recently but not sure about immediately after the overheating problem began.

Next thing I'm trying is to remove the thermostat and try running it again.

Is there some single place that blockage could occur that would cause this?

Any ideas? fixes?

TIA.

Steve

[parkerbink]

I had the exact same issue. I had to bleed my cooling system opening the valve on the thermostat.

[EverWiser]

See my response to this in your other thread...

[bichmgnt]

All fixed

Problem solved. Bleeding was the answer. But not your ordinary let the air out at the bleed valve kind of bleeding. I did that at least six or seven times. I even tried running without the thermostat, bleeding it, and then running it and it seemed worse, if possible.

What I eventually did was, with the thermostat out, take off the upper end of the hose between the thermostat and the water pump and make that the top of the water pillar. I closed off the hole on the thermostat. I then took the hose off the upper heater outlet (which is fed from the back of the engine), closed it, and put a hose on the outlet to make its end higher. Then I poured water into the hose to the pump and blew through it to get water coming out of the heater and out of the reservoir. Once that was full of water (a couple times) I put the hoses back on everywhere, bled it at the top of the thermostat and ran the engine again without the thermostat. This time it stayed nice and cool. Finally! Took it for a drive and it never got out of the blue. Went back and put the thermostat in, bled it normally and took it for another ride. Normal operating temps at last (actually it seemed low - between 1/4 and 1/2), the heater works and all seemed well.

Until I got home. Pulled into the drive and let it idle. Watched the needle climb past the center of the gauge almost up to 3/4. Noticed the idle seemed low - about 600 rpm. Raised the engine speed to between 800-1000 rpm and temp went back down to the center so that was good. My guess is that the water pump doesnt turn fast enough or the fan doesn't turn fast enough at that low of an idle to cool the engine. So do I now have to adjust my idle speed to keep the engine from overheating?

Thanks to all for your suggestions.

Steve