On my 02 dakota 3.9 does it have a bleeder screw for the coolant? I think there is air in it since I replaced temp sensor an thermostat .
I'm having a issue where tempt won't get very high an ive replaced thermostat, temp sensor,an even iat sensor .since some background errors had shown on scanner many coolant tempt sensor errors an a iat error also [intake air temp sensor]..still showing after Replacement too.
Thermostat in dash seems to stay at 30% no matter how long it runs .
Scanner tempt went to 185 fot while maybe 190. An steady at 190..manifold temp 156...LOW too long .
Any ideas?

Can air or even heater core issuescause all these issues an will jacking up truck an bleeding system work to help issue?

Thanks

 

The system is self bleeding as the inline radiator cap is the highest point in the system on the pressure side of the flow. Yes, jacking the front up may help a little bit if there is an air bubble at the back of the heads.

for an 02 3.9 you are seeing about the right numbers on the water, as that's where my 01 3.9 hangs out with a 180 stat (factory stat is 195). I can usually see the thermostat open an close in cold weather, as it will go up 10-15 degrees then suddenly drop back down, creep back up 10-15 then drop back down. Lowest I've seen it was 10 degrees outside and it was swinging 175 to 190 and back. Never had a temperature malfunction code form it though.

 

Thanks for the reply.Does your guage only go about 1/3 an not fully to the center as mine does..? That too has me stumped..
Glad it's common to have these tempt on my truck.
I did jack front up an did a few periods of letting it warm up to 188 for a while with cap off.adding coolant some as it went down with bubling.
​​I let it cool down overnite ,cap loose.
In morning it did require a good amount of coolant to go in to hose at block ,an im going to do this 2 or 3 times to try to get maximum amounts of air out.

On scanner I also noticed MAP sensor readings are at 9.4in idle..


IS this range normal..?
oddly another scanner I tried showed 4.9 right after trying other ..
Not sure if either is normal range in idle..
Any info is appreciated

This is where its at at 185 degrees an fully warmed u​​​​​​p

 

don't trust the cluster. Trust what OBDII says. The stepper motors in the cluster are terrible for accuracy.

Here's mine-

 

What about the map readings,TP reading an a high iat at idle?

 

The IAT heat-soaks and frequently will read high at idle if the water temperature is high. Once you open the throttle and have air moving inside the manifold, you'll see it drop down a few degrees. Plus the IAT itself could be offset.

Throttle percent is relative, the potentiometer isn't always closed or all the way open. It's a range. I think closed is usually 1.15 volts and open is 3.8 volts or thereabout.

 

Thanks for the important info on readings.
So does everything look good overall on chart as to being normal range from what you can tell?
I wasn't looking at STFT or LTFT nor 02 info as much .Though I just replaced the 02 sensor ,downstream.Any info is apreciated.
Thanks again .

 

If it's running fine, roll with it. If you get too cold/too long codes, cover half the radiator with cardboard.

 

Just noticed fan is on always with engine....ac an fan off .​​​​​
I don't think these are made to be on at start .

Should I be looking at relay an fan circuit?
And do you think this is why that temp on guage is staying low ?
189 was temp driving it .

 

Electric fan should only be on when water hits 210 (shuts off at 200 IIRC), when AC is on, or when Defroster is on (Ac on). In winter, clutch fan only should be plenty sufficient. I haven't had a clutch fan in years, have the fan adjusted in SCT to come on at 190 and off at 185, with 180 stat