Engine not hot enough

[amason]

Hello all,
I have a tempature problem on my 1994 chevrolet pickup, 350 with air, trans cooling and oil cooler.
The temp only gets to 140 to 150 degree instead of 180 to 190.
I had to replace the radaitor due to a crack in the old one.
I also replaced thermostate ( TWICE thinging the first one was bad, new hoses and a new cap. (195 degree stat installed).
I have plenty of heat in the cab.
The radiator was an after market replacement.
I would like to get the temp back up to where it use to be (180 to 190). My gas millage was better then.
I have noticed that the heater hose flows a lot of coolant back to the radiator. Should there be some kind of restriction in the line?

Any suggestions?

[Piston]

where are you getting your figures from? First step would be to verify the actual coolant temp with either a infrared gun or using a scanner to verify temp.
Its very possible you have a faulty temp sender for the gauge or a gauge that has lost calibration.
The heater core should flow a solid 5/8 stream of fluid back to the radiator, good indication of a healthy waterpump
There are no restrictions in this model.

[superchevy]

Was the gauge reading 195 before you changed the radiator?
If your gas mileage has dropped noticeably since the radiator install and the temp gauge was working prior and now reads 140, sounds to me like you have the wrong thermo installed and you're running rich as computer is in constant warm up mode.
(I had this happen after I was told a colder thermostat would make more power in my truck, installed a 160 thermo, ran super rich and crappy, reinstalled the 195 and runs great)
Be sure the thermo is a 195-er and not something the parts guy says is "the right one".
Also, what's your coolant/water ratio?
Just a thought.
SC

[amason]

The temp reading that I am getting is coming from the factory guage and from a digital temp meter with probe at the neck of the thermo housing. The factory guage reads between 140 and 160, the digital meter reads around 150.
I have put in two different thermostats, both stamped 195. I checked the second to make sure that it was opening and closing by boiling in water.
Before changing the radiator the temp was always running between the 180 and 200 mark on the factory guage. I will try to find a more accurate way to check the temp.
I had a coolant leak for a while that I could not find. I thought that was the problem. I finaly found that the intake gasket was leaking on the front corner. After fixing the leaking intake gasket
I thought this might take care of the temp problem, but it did not.
I am not sure what else I can do short of putting cardboard in front of the radiator or buy a GM radiator which I hate to do.
I guess I should expect some problems out of a truck with 200K+ miles on a factory motor, trans and rear end. I hope to get another 100 or 200k miles out of her before I put in a new motor.

any suggestions appreciated.
Thanks

[superchevy]

Wow. That is unusual.
I can't think of any other explanation other than the new radiator must be the problem. Just doesn't make sense to me, though.
I've changed intakes and thermostats on my truck and it's never acted like what you describe except for that 160 thermo adventure.
It's got 205,000 miles on the original engine, trans, and rearend also - as well as the original radiator.
Are you using the original thermo housing?
Had a buddy one time using an aftermarket chrome housing that would put pressure on the thermo when tightened down causing thermo to stick.
Just an idea.
I'm stumped.
You might put this on the engine board to get some other responses.
SC

[amason]

It does not make sense to me either.
Yes! I am using the factory thermo housing.
I guess the new radiator must cool a lot better than the factory one.
This is the first time I have ever had one run too cool.
Most of the time it's the other way around.

Thanks

[CEDRLM]

If you had a 2 core radiator in there and changed to a heavy duty 4 core radiator that would cause exactly what you are describing. Had it happen myself going from 2 to 4 cores.

[Piston]

Thats why there is the thermostat though. No matter how cool you keep the radiator, the engine coolant should always remain at 190 once its started building heat.

I have seen on some models if the heater core flows so much coolant through itself and dumps it back into the radiator, that forces the waterpump to pull coolant from the radiator instead of circulating it within the engine. On those models (when there's a customer complaint) I'll take the plug out of the waterpump and run the exhaust hose from the heater core directly to the pump inlet and cap off the radiator. Your's may already be like this? GM eventually stopped routing the hoses like that.

You wouldn't think it would make much difference since the exhaust hose from the heater core is going to the outlet side of the radiator, so in theory it shouldn't draw in cold coolant but it does. And in a cold climate, your cooling system will take for ever to come up to temp.

Try a simple test.... Crimp off the exhaust hose from the heater core (the one going to the radiator) and take it for a spin. The heater is not going to work but at least you can see if the engine temp comes up to normal. Its very possible your heater is bypassing the thermostat enough to cause this problem.