04 300m overheating FIXED IT THANKS!

Well took it apart today toget the termostat out. Sure enough it was the problem! Dads been a mechanic since middle 60's and said he has never seen one look like this one. The middle rubber ring seal was so swollen up it actually locked the thing shut. When we pulled it out there was no question it was the problem. We had the radiator out so we flushed that and cleaned the fins. Before we started doing that I tried to find a couple plugs to cover the tranny lines. I had one drawer open on my bottom box and one slightly open on the top box. Went looking in my junk drawer with all my odds and ends which is in the top box. Slid it shut walked away only to hear this creeking as I turned around I see my box tipping over and there was nothing I could do but go OH F@#k! Ended up bending 4 guides on the top box and 2 on the bottom box. Its a snap on Doug herbert eddition box so it damaged that while also dumping all my tools all over the shop floor. I was just saying I should go through it and clean it out but sure didn't want to do that tomorrow! Oh well car is fixed so if it wasn't the problem it sure would sting alot more!
I want to thank all of you guys for your ideas and directions and help! Sure glad we have moparts! Thanks so much!


We went to winconsin dells this past weekend. While sitting in the drive through the car overheated to point that the idiot light chimmed. Here is what has been done or checked.


I got it cooled down released the pressure valve and thought maybe that was it. Still just driving it around in motel parking lot it ckimbed back up. Did that again except this time I opened the burp tank with car running then released the bleed valve. It sucked the tank down right now and burped air out the valve until it came back up through the burp tank.
No water in oil.
Doesn't appear to have steam out of exhaust
No oil in radiator
Fans turn on
Don't hear any traditional noises from water pump or see any leaking fron that area
pulled all plugs and they don't look like they have been washed. Actually are a light tannish brown ish color.
Used a cylinder leak down tester on 1st 2 holes but did not get it to work where I thought it wouldshow bubbles in burp tank. It actually wouldn't hold any pressure. Actually figured i was getting TDC wrong since I was having my 6 year old daughter bumping the switch.

So any ideas? Was thinking maybe the thermostat might be stuck shut.

thanks
corey

help anyone?

If both fans are running, I would check for junk laying in front of radiator, or the radiator itself is a bit plugged? Those are pretty bada-- head gaskets and wouldn't change them without good reason. Thermo replacement is good idea, and get a dealer piece if you can.

T-Stat is probibly bad. If the air blowing though the radiator is cool when the gauge is hot its probibly the T-stat.

If its the 3.5 V6 in your 300 , I'll bet its a head gasket or cracked head . if your getting pressure in the burp box every time you open the cap after a run , it just means that compression is getting into the coolant . when that happens all hell breaks loose. You can confirm that your fans are working ?

Those cars had problems with the fans not working properly.

The fans are working. We checked all 6 cylinders by using the cylinder leak tester I have. We screwed in the hose,hooked up the regulator to air then turned the motor over til each one was at TDC. Had no air bubbles in the burp tank. Going to try tomorrow night to put plugs back in it,make sure the radiator is full and run it. This weekend when it was running I didn't really pay attention in the tank to see if there was flow in the burp tank.

Also when I was creaping it back to the motel in city driving or around the parking lot it would rise really fast but sunday am when I took it down the interstate after it sat all night long the temp gauge only went to half but as soon as I got off the interstate into traffic that was not real busy but slowed down to maybe 35 it started to slowly rise till I was in stop n go as I went into the motel parking lot where the dance competition was at. Like I said I know the fans were working cause I heard them and felt them and I also switched the relays around that were related to the fans and nothing changed.

Id check the thermostat

I can tell you that I worked for a Dodge dealer for the last 25 years and we had some head gasket problems with the 3.5 Intrepids now and then. Not alot but a few I could not forget about because they never showed up as a head or gasket problem. But I can tell you the car would usually come in with the overflow (burb) tanks partly melted. And many times you could let it sit and idle and after a bit the fans would come on but they would not bring the temp back down cool enough to turn the fans back off unless you drove down the road. One of the techs had this car an after a rad and thermostat and everything else we tested looked good he decided to pull the heads and they were warped enough that we had to replace them with new head gaskets. But we could not detect any combustion in the anti-freeze with our tester or see any air bubbles with air in the cylinders. We had a few more over the last 8 years or so that ended up needing the same thing. The funny thing was this tech and I always like to diagnose the problem the best we could and know what we thought was wrong before pulling anything apart but the first one we had we ended up pulling the heads not sure if we would find the problem since everything seemed to test ok. Good luck with it. Ron

Well got everything back in the car and started it. Ran in the shop for a good 10 minutes. Never reached half way on the temp gauge. Watched the burp tank and it appeared there is flow in there. Checked the inlet and outlet hoses on it and they both were warm. So that tell me the water pump should be ok. Felt the top hose and it was warm. lower hose was cold. Fans turned on but only the left side on low. Switched the relays out with the auto shut down one. They all were good as the car started with each one in the auto shut down spot. Next I undid the wire connector for the fans. Ran power from my jump box to the 4 terminals one at a time. I could get the drivers side to run both high and low. passenger side at 1st just squeeked. hit on it and it would only turn on low at a very slow speed. So does it sound like a fan replacement issue to anyone?

thanks guys!
corey

Possibly, as my 2000 3.2 intrepid fans run together to my knowledge.

The fans turned out to be ok. I let it run for a good 15 min. and they both turned on high. The temp stayed on half the whole time until the fans went on high. Then it would slowly creep up above high. The hoses on the tank were both hot and the upper was hot. The lower was maybe luke warm. The car had alot of pressure when it got above the half mark. Would a gasket expand when it got warm then leak where when we did the pressure check the car was cold so maybe sealed up? Trying to figure it out best as I can before I rip the heads off.

Sounds like a plugged radiator to me. It stays cool at highway speeds when the air can be forced past the fins. But when you slow down, little air gets past fins. Check for debris in fins first. Then check coolant flow through the rad.

thanks guys will check this all out tomorrow.
fingers crossed

bump. See the update in the 1st post on this. Thanks guys!

Glad you got it! I thought you were going to say the toolbox fell onto the car.

I've had a thermostat stick closed also. When I pulled it, you could see deep scuffing on the shaft where it had been rubbing hard before it finally stuck shut.