I just got a 98 dodge ram 5.2 4x4 im the guy I got it from drive an hour to meet so I could buy it got it home I towed it back because I didn't have no one go with me to get I went outside to crank it and within 3-4 minutes it went straight to temperature handle on gauge maxed out and check gauge came on I turned it off checked for leaks no coolant leak and radiator full of coolant I felt too hose still soft and mostly cool bottom hose was a little warmer but not didn't feel hot enough to overheat. Let it sit a few mins still stuck on max temp looks like the previous owner just put on a new clutch fan and water pump doesn't look very old any ideas what it could be or were to start just don't want to run it hot? Please help

 

The radiator wasn't even to hot to touch you could open the cap with no spew

 

Check the coolant temp sensor for the gauge, they can and do go bad and will give you false readings

 

I had a guy look at real quick tonight and he said it felt like it wasn't circulating? What would cause that? And I'm putting new sensor in the morning it's below the alternator correct

 

I did notice on cold cranks the temp gauge goes direct to about 160-180 degrees does sit on cold at all and it went from startup to temp being maxed out in 5-6 mind exact

 

Its right behind the alternator. You will need to remove the air hat, a couple wire harnesses and remove the alternator iirc. Might get away with loosening the alternator. I don't remember how close the 2 are.

You are going to have to remove the cables and harnesses going to the alternator tho..
Make sure you put some sealant on the new sensor threads if not present.


As far as the cap not spewing. You have a leak somewhere. Which is not letting it build up pressure. It can still circulate, but not build pressure... Do a leak down test. The tool can be rented at your local auto parts store.

 

And be VERY careful with the temp sensor wires unless you feel like splicing and soldering. And don't worry, the wires don't matter. The harness is reversible.

My dads wires were corroded, dry rotted and had bare spots. So I just soldered in a new harness from a scrap truck.

 

Is a bad temp sensor gonna start off at 150-160 then go up to maxed out in 5 mins?

 

And also is the temp gauge starting at 140ish on gauge normal

 

Double check the serpentine belt is routed correctly and is spinning the water pump in correct rotation. Someone a few years back had that problem.