lower radiator hose cool to touch after driving?

[gavinl]

I got a 1997 Subaru Impreza with about 20k on rebuilt 2.2L motor.

Winter ambient temps are in the 20-30s here.

I have been noticing that my coolant temps are rising to ~210F compared to staying at 190F before winter. When I got home this evening, the lower hose is cool to touch, top hose and top of radiator are warm and radiator cap is cool to touch.

Warm up time doesn't take much longer, car drives the same. I have an aftermarket mechanical water temp gauge plumbed into the heater core outlet hose. The dash water temp gauge always stays pretty in the center.

Thermostat is subaru part that came with the rebuilt motor. Coolant is OEM with 10 months use on it. Thermostat is located at bottom of motor as this is a boxer 4-cyl (see #6 in pic below).

Could the cold ambient temps have kept the thermostat closed longer or slowed the thermostat function? And is it possible that the thermostat was closed when I got home and checked the lower hose?

 

[The_Jeff]

yes and yes. An infared noncontact thermometer should show a linear decrease in temp across, or up and down, the rad as it cools.

Sometimes temp gauges are contrarian, my dodge spirit was this way. If it probes part of the water jacket way far away from the thermostat, if the air is colder, the thermostat is almost all the way closed, so flow is less, so the coolant heats up more by the gauge sender. (which is why dash gauges are "dumbed down".)

People will say, "ah, it's in bypass, you're still getting lots of flow" but some cars the bypass hoses are much skinnier... I can buy less flow.

 

[ChiTDI]

Did they put in a 210 degree thermostat?

 

[mechtech2]

The lower hose on almost all cars is the cool one. Hot coolant enters from the top of the radiator, and goes down and out the bottom to the engine.
So this may be normal, in winter.

 

[Gary Allan]

Did they put on a new water pump with the rebuild?

 

[gavinl]

Thanks guys!

ChiTDI, the factory thermostat is 170F

Gary, a new water pump was included in the long block

 

[mechtech2]

did the rebuilders use the 170, or is it really recommended by the factory?
170 is really low. I would never use one on the street.

 

[gavinl]

Originally Posted By: mechtech2
did the rebuilders use the 170, or is it really recommended by the factory?
170 is really low. I would never use one on the street.


I did not verify that. That's the OEM spec and the rebuilders claimed to use OEM parts only.

 

[mechtech2]

Well, I'd check it out, for sure.
170 is abnormally low.

 

[c3po]

My 1983 Chevrolet El Camino calls for a 195 degree thermostat.

My 1979 Pontiac Bonneville calls for a 180 degree thermostat.

I thought everything from the 1980's up to today was speced for a high temperature thermostat to burn off any harmful emmisions.

I think they used something that low, meaning 170 degrees or lower back in the 1960's.

I would call the Subaru Dealer and ask them, this does not sound right.

 

[another Todd]

Originally Posted By: mechtech2
The lower hose on almost all cars is the cool one. Hot coolant enters from the top of the radiator, and goes down and out the bottom to the engine.
So this may be normal, in winter.


Yeah, but skin burns when it reaches 113F, so it won't feel "cool". It will feel cooler than the top hose, but not cool.