86 Chevy Won't Heat Up

[1986K20]

My 1986 3/4 ton 350 won't build engine temp when it is cold out.  Everything seems to be in order-thermostat, water pump, timing, etc.  I have even put cardboard on the radiator and in front of the grille.  According to the temp gauge it will only get to about 150 degrees.  On the other hand it likes to overheat on hot days pulling a load when the right foot gets heavy.

Any suggestions?

[roundedline]

What size thermostat are you using?  What does the radiator look like inside?

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

[1986K20]

It is the reccommended thermostat.  195 I think.  I have put at least two in.  The radiator looks fine to me.  I just can't figure out why I have both extremes.  Seems like it would either get hot or not heat up at all.  Seems like it is directly proportional to the outside temperature.  I have had this truck for 4 years and it has always done this.

Matt  

[DnStClr]

I hope your heater core isn't plugged. In the engine bay, there are two hoses going to the heater. One is inlet and the other is outlet. If the coolant is circulating thru the core, both hoses should be hot to touch when the engine is warmed up.
 If the coolant is not getting up to temp, it must be restricted from going thru the engine.That's where the heat is, and that's how the coolant gets warmed up as it circulates.  

Don St.Clair
Culleoka Tn

[aort07]

I have a 180 thermostat on mine and it seems fine, summer or winter. Its 90 here in the summer and just today it was 10.  

[73customC10]

throw in some eleletric fans so you can control it yourself lol. on or off. hot or cold