Engine runs cold

[ThatDangDodge]

I've got a 1988 w100 with the 5.2L 318. I changed the thermostat today (as of posting) and the truck still doesn't warm up beyond the first notch past cold. I've tried looking it up to try tracking down the issue but all I can find is a bunch of articles saying "replace the thermostat." Can any of y'all help point me in the right direction? Maybe I got a bad thermostat?

 

[crazykid1994]

Or the temp sensor is bad? You can actually check the thermostat on the stove and see if it’s sticking open. Also I would use a thermal temp gun to check the temp of the water pump where the upper radiator hose connects when “warmed up” and also I would feel the upper radiator hose to see if it feels hot and is holding pressure. If it’s hot then change the temp sensor. If that doesn’t fix it then the gauge could be going bad.

 

[ThatDangDodge]

Part of why I ask is I'm still not getting heat through the heater and so far, the heater core is the only thing I haven't changed yet. Reckon I'll try a temp sensor come payday, just to come near making sure it's good and hopefully reading right. Thank you for that though because I honestly didn't think about the sensor being bad

 

[threewheeler80]

I recently replaced the original heater core:

What a task! But now the heater/defroster is working.

 

[ThatDangDodge]

I recently replaced the original heater core:
View attachment 484728
What a task! But now the heater/defroster is working.

Isn't the heater core on these trucks behind the dash? I haven't gotten around to looking for it yet and it's currently too cold for me to care about it

 

[threewheeler80]

it felt like under and behind. It was not very much fun. While it was being replaced, I cleaned out 5 lbs of sticks, leaves, and dirt.