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Engine not reaching operating temperature, no heat in cab
2nd Gen Ram Tech1994-2001 Rams: This section is for TECHNICAL discussions only, that involve the 1994 through 2001 Rams. For any non-tech discussions, please direct your attention to the "General discussion/NON-tech" sub sections.
Just noticed a small amount of coolant on the thermostat housing. Not enough to run over the lip of the bottom of the housing, but it's there. Perhaps a crack in the housing or a tear in the gasket? Could this be the source of the air in the system?
Probably not enough to bother you. I'd pull the thermostat housing and inspect the thermostat. It's possible you got a bad unit and it failed open. I'd then check the timing. Your engine is at the right mileage to need a timing chain. I had a 1994 with the 3.9 and it was almost exactly where your temperature gauge is. Have you noticed a drop in fuel economy? Replacing the timing chain with a new one with the updated tensioner got the temperature up where it belongs and my mileage went from 16 on the highway to 22. with it running, do you hear a shika-shika-shika sound from the front of the engine?
The duralast probably opened the first time and stuck open. Get a Gates or a Stant Superstat. Take the cap off and see if there is a hole for the hose to the overflow tank. I had to drill the hole on the radiator I bought. They glued the hose barb on, but didn't drill the hole.
Overflow hole is there. Ordered a new thermostat housing. I'll order a new Gates thermostat too.
Probably not enough to bother you. I'd pull the thermostat housing and inspect the thermostat. It's possible you got a bad unit and it failed open. I'd then check the timing. Your engine is at the right mileage to need a timing chain. I had a 1994 with the 3.9 and it was almost exactly where your temperature gauge is. Have you noticed a drop in fuel economy? Replacing the timing chain with a new one with the updated tensioner got the temperature up where it belongs and my mileage went from 16 on the highway to 22. with it running, do you hear a shika-shika-shika sound from the front of the engine?
Don't really hear a shika noise. Ordered a new thermostat housing and gonna get a new Gates thermostat.
Takes a bit to get to it, but it's not that hard. I tore the oil pan gasket so I had to take my oil pan off. I prefer Felpro gaskets. The biggest problem guys have is using the correct marks on the gears. The small dots are the correct timing marks.
This morning I drove it up onto the sidewalk to give it more incline(see attachment...enough incline?). Pumped the bottom hose with the engine running and got some air out. It's been running for nearly an hour and the temperature won't go any higher than what you see in the picture. Top hise is warm to the touch. Bottom hose is ice cold. Both heater hoses are warm.
Thoughts?
Need more incline, I do believe you're thermostat failed as even with an air pocket it should heat up. It's possible they gave you the wrong temp thermostat
And the gauge doesn't go up much higher than that, even when the engine does get to full temp. I changed my thermostat on my 8.0 because I thought it wasn't working. Was in the same place after the change, so, plugged in a scanner, and sure enough 195 degrees..... I really didn't need to change the stat...... So, plug in with a scanner, see what the PCM thinks temp is. (replacing the stat is still a good idea.)
Don't really hear a shika noise. Ordered a new thermostat housing and gonna get a new Gates thermostat.
Changing the timing chain is a big job, right?
Being a truck and a first generation Magnum, it isn't too bad. I usually drop the oil pan and clean it. The front of the engine does need to be disassembled. It's not the worst repair, but it does require some experience. I'd change the thermostat and see what happens. Get a remote thermometer to check the temperature separately from the gauge.
Being a truck and a first generation Magnum, it isn't too bad. I usually drop the oil pan and clean it. The front of the engine does need to be disassembled. It's not the worst repair, but it does require some experience. I'd change the thermostat and see what happens. Get a remote thermometer to check the temperature separately from the gauge.
I don't have an infrared thermometer, and if I spend the money get one, my wife is likely to cut my junk off. Can I use a meat thermometer(with a probe) to check the coolant temp?
I don't think that will be as accurate, but, it's worth a shot. Hold it up against the thermostat housing.... sticking it in the radiator fill hole will give you a VERY low reading.
And the gauge doesn't go up much higher than that, even when the engine does get to full temp. I changed my thermostat on my 8.0 because I thought it wasn't working. Was in the same place after the change, so, plugged in a scanner, and sure enough 195 degrees..... I really didn't need to change the stat...... So, plug in with a scanner, see what the PCM thinks temp is. (replacing the stat is still a good idea.)
Previously, before replacing the plenum gasket, injectors, top end gaskets, radiator, and ac system, the gauge went up to almost 200* before coming down, and the heat in the cab was excellent. Now no heat, temp gauge only goes as far as pictured, and a small coolant leak at the thermostat housing(replacing the housing, thermostat, and gasket today). I'm hoping that, as MoparFanatic suspects, the thermostat I put in failed, or was somehow stuck open, and that a new thermostat will allow the engine to reach normal operating temperature.
10-17-2019, 12:43 PM
I changed my thermostat on my 8.0 because I thought it wasn't working. Was in the same place after the change, so, plugged in a scanner, and sure enough 195 degrees..... I really didn't need to change the stat...... So, plug in with a scanner, see what the PCM thinks temp is. (replacing the stat is still a good idea.)