Vehicle overcools AFTER a new thermostat

[aluminum13]

I searched but didn't find any clear answers.

My cb would both

- overheat after highway driving when stopped and idling
- overcool in a variety of situations just driving down the road and take a long time to warm up.

I know this seems contradictory. The temperature of the heat blowing out of the vents corresponded to the temperature gauge - that is it would blow cold when it said cold and hot when it said hot.

It would overheat to about the 3/4 mark and start to go back down with full blast heater on and runs cool at around the 1/4-1/3 point.



I replaced the thermostat with a Honda one and the rad cap with a 16lb generic. It now runs steady at 1/3 point and blows warm air.
I removed a non honda thermostat (came with car) and what I think was the original rad cap.

It has been in the 20s around here which is unusually cold for the area. I'm using 50/50 antifreeze.

What's going on?

I want to drive up to NY (4 hours) but don't want to cause damage and rather have a warm engine.

[GeoffM]

I guess water pump or air in your coolant lines.

[wed3k]

drive it.

[accordztech]

feel the top and lower hose when the engine is warm or over heating. are they the same temp, if so then that confirms a good thermostat.

bleed the system (with heat on full blast) with the 8mm bleed valve on the thermostat housing. leave it open till there is no bubbles.

[aluminum13]

I guess water pump or air in your coolant lines.

I replaced water pump myself when I did the timing belt maybe 15k ago. How would I know if there's a problem with it? (No coolant leaks.)

As for the air...(see below)

drive it.

Probably will. Cute girl waiting for me in NY>warm engine.

feel the top and lower hose when the engine is warm or over heating. are they the same temp, if so then that confirms a good thermostat.

bleed the system (with heat on full blast) with the 8mm bleed valve on the thermostat housing. leave it open till there is no bubbles.

As for the air...I flushed and drained the coolant. There were some deposits but nothing terrible, but enough to partially clog the FITV coolant line a while back. I did use the bleed valve and burped the upper hose.

How long should the bleed valve stay open? A few seconds and it seemed like a good stream so I shut it off. Longer?

Also I think the bleed valve is 12mm. The one on the t-stat housing.


I'll try more air line clearing.

[blazenem]

As for the air...I flushed and drained the coolant. There were some deposits but nothing terrible, but enough to partially clog the FITV coolant line a while back. I did use the bleed valve and burped the upper hose.

How long should the bleed valve stay open? A few seconds and it seemed like a good stream so I shut it off. Longer?

Also I think the bleed valve is 12mm. The one on the t-stat housing.

I'll try more air line clearing.

maybe more air worked its way through the system