1998 Dodge Ram 5.9L (Basically stock)

What is the normal operating temperature supposed to be? If I had to guess based on the temp gauge, it sits between 170 and 180.

What is the stock thermostat supposed to be? Not that it matters if my engine temp really is below 180.

I know I have a cable operated blend door. I know it is actuating properly and seating somewhat tight on both hot and cold side. Both sides of the heater core get very hot to the touch. I usually change coolant every spring, and a few years ago I flushed, back flushed, and even isolated and flushed the core.

I get warm air from the vents when it's on vent. If it's on defrost it's not as warm. I assume this is partially due to cold air leaking around the blend door, since the defrost setting turns on the compressor. This would not explain why I don't get HOT air from just vent.

I'm kind of leaning towards an engine that is maybe 20 - 30 degrees under optimal operating temp.

Thoughts?

Thanks.

 

Stock thermostat is 195 degrees. The gauge also isn't real accurate, and sometimes can be difficult to interpret. (I changed the thermostat on my truck, thinking it was running too cold, only to find that the gauge stayed in the exact same place with a new stat..... plugged in my scanner, and yep, thermostat was actually fine. Engine is at correct temp, just was unfamiliar with the gauge, going from a 96, to a 98.....)

Think I would plug in with a scanner, and see what the PCM thought engine temp is. If it is low, change the stat, to a 195 degree stant super-stat. (NOT the failsafe fellers, they suck.)

 

I know these gauges aren't super accurate, especially if someone had the gauge face layover removed and didn't get the needles back on perfectly. At operating temp right now, the needle sits almost perfectly between 130 and 210. That's why I'm guessing 170, and allowing for error, a few degrees up.

Getting it scanned is on my list.

 

That's what I thought too... (as far as temp....) But, the scale most certainly is NOT linear. Plug into it, and verify temp. It's probably ok....... Getting all the air out of the heater core though, that is a right pain in the ****...... Might try installing a flush 't' in the outgoing line from the heater core, as close to the core as you can get. Start the engine (COLD), and loosen the cap a bit and see if you get any air out.

 

Just so I don't get it confused, which is the heater core inlet and outlet, and which line comes from the water pump? I want to verify those hoses are not backwards.

 

The hose from the passenger side of the intake runs TO the heater core. (and goes to the passenger side connection on the core itself) the one that runs from the drivers side of the core, to the water pump, is the outlet for the heater core. (runs around the drivers side of the engine.) At least, I *think* that's how it works.

 

Good, that's how it's set up currently. As I said, relatively stock and the only previous owner is my Wife's Grandfather.

I was thinking of a way to check for trapped air, was to clamp one of the lines to the heater core with the engine running and warmed up, rev the engine up, and then quickly release the clamp. The way I imagine it, the rush of pressurized coolant might grab any air pockets and take them with the flow.

 

Worth a shot.

 

Read post # 14 This will let out most of the air. (fill cooling system)Leave the cap off and start the truck and add coolant if needed.
https://dodgeforum.com/forum/2nd-gen...p-bleed-2.html

 

I actually already have a drilled thermostat. I've been doing that for a long time. I don't think I have air trapped in the main system. This is just a precaution in case there is air trapped in the core.