Truck running hot, slightly overheating

[Electrician4you]

Originally Posted by oldtimebanjo

I have a 97 Dodge Ram 1500 3.9L with about 100k miles on it. It always ran fine with the temperature being right in the middle. Well now the temperature will go about 20 degrees over so it's not full blown overheating but is definitely running hot. While driving it will cycle back and forth from the 20 degrees over and back down to normal temperature. and then sometimes it will stay put about 10 degrees over or even normal. It can do all of those things over the course of a 10 minute drive. But when I stay parked and idling it will never drop back down, it will stay at that 20 degree over normal mark. When I proceed to drive from that idling point I will get a brief rush of liquid noise from the dash.

I also have a fluctuating idle, it sounds like your lightly pressing the gas and taking your foot off. Whether that is related or not I don't know.

Any help would be greatly appreciated, thanks.

You might have a leaking heater core. Your coolant level is low so it's running hot. Could be a clogged radiator too but if you got gurgling under the dash the heater core could be a issue.
If you want to make sure remove the two heater core hoses and get a barbed fitting of correct size and connect this'd wires together. Fill the coolant reservoir and radiator to correct levels and drive it. If the overheating and noise goes away then that is the issue.

[oldtimebanjo]

Ok I'll try that out as well. I tried to bleed the truck longer this time, it was running at 20 degrees over normal when I shut the truck off with the radiator cap also off. A fair amount of coolant boiled over and out. Was this normal to happen?

[brownbagg]

to me its sound like the fan clutch, no air at idle, plenty going down highway. if it was me, i would flush radiator, new waterpump, fan clutch and themostat in one weekend, cost about $200 but it would solve the problem

[Electrician4you]

Originally Posted by oldtimebanjo

Ok I'll try that out as well. I tried to bleed the truck longer this time, it was running at 20 degrees over normal when I shut the truck off with the radiator cap also off. A fair amount of coolant boiled over and out. Was this normal to happen?

Auto correct kicked in. It was supposed to say to connect the two hoses together. The gurgling means you got air in the system. Which means its leaking or going out somewhere. Do you smell coolant in the cab when heat or Ac is on? Haze on end shield when using defroster? Wetness on passenger side floorboard? Those are sure signs of a leaking heater core.
Could be anything from a clogged or cracked radiator, bad heater core, bad radiator cap, pinhole in a radiator hose leak at thermostat housing, stuck thermostat, bad fan clutch, bad water pump, bad manifold gasket, head gasket. All you can do is check and eliminate what isn't wrong.
Crawl under the truck and look at the water pump. You'll see a hole right at the snout of the pump right under the impeller shaft. It's called a weep hole. If you see coolant or traces of coolant running down the body of the pump and lower radiator hose most likely a pump is going bad. Sometimes they only leak if the truck has ran for a while. Too much stuff on there? Wipe it down and sprinkle baby powder on the hose and pump through a squeeze type baby wider bottle. The baby powder will soak up the coolant and you'll see the wet/disturbed baby powder. Some will get blown off by the fan but not all of it.
Could be you got a bad radiator cap and you're losing a tiny bit of coolant because the system just isn't pressuring.
I know the 318/360 had a issue with coolant loss at the intake manifolds. So if you're losing coolant but it's not leaking that's most likely the issue. I had that happen one Chevy truck.

As for the fan clutch you can test it. Make sure your radiator is full then just start the truck and leave it idling. Grab a piece of cardboard and cover the grille. You'll hear the clutch kick in because it's gonna have a roaring sound like a airplane.
Or in the morning pop the hood and spin the fan blade. It should move and spin easily. Go to work and when you get there shut off truck pop the hood and spin the fan. It should be harder to spin. If it spins easily then the fan clutch my be bad. Fan clutches on those trucks don't go bad very often. They can its just not often that they do.

There us just a lot of things it can be. Start by looking for visible leaks of coolant eliminating what it isn't

[brownbagg]

i had an s10 that blew an heat coil, they was prone to do that, finally one day no heat, later that day, no engine. so yse it could be neater coil too. leaking water