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Chrysler 300M Overheating mystery



  • gking101gking101 Posts: 1
    I can use the Cd. Email me at
  • littleearllittleearl Posts: 1
    I see you have offered the entire collection of Chrysler Service Technician Manuals , which are over 10,000 pages (on CD only) , for the 2002-2004 300M's / Intrepids and Concorde vehicles - FREE on your Edmund's post.

    I am very interested in these as I am starting to need more in-depth instruction on repairs for my 2002 300M. Could you please send me these? Thanks so very much!
  • Due to forum abusers (who will not even refund me any postage) , the only
    way to get the CD , is to send $6 to my Paypal address : - so that I can pay the postage (while the CD's contents are still FREE). If you send $6 , be sure to also send me an email at the same email adress , so that I will send the disk to the address you want it to be sent to. The manuals are authentic Chrysler (not altered or reprinted etc. manuals). Worth alot more than $6. I have sent about 60 of these in the last 2 years. It's a no-brainer .
  • bookiettbookiett Posts: 1
    I recently changed the radiator thermostat fan fan relay switch belt and the engine isn't getting hot and the internal cage is only going up to half mark but the water/antifreeze in the resevior is bubbling or should say boiling then steaming out.. Any ideas??
  • pitmanoeuvrepitmanoeuvre Posts: 68
    edited July 2013
    If your engine temperatures are normal , then you can assume the waterpump is OK , but you may have put the thermostat in backwards / causing the overflow reservoir to become a radiator. It is possible , that when you change a thermostat and follow how the thermostat is already installed (at which time you are also changing the thermostat because ? the engine is overheating?) , you will have repeated installing the thermostat incorrectly - if you match the direction that the thermostat is placed. Any time you change a thermostat you should be checking that the closed position is towards the engine - while the spring/open position is towards the radiator.

    In some cases boiling of the fluids indicates that the waterpump is not functioning , but your interior temperature gauge should show a maximum reading as well. Whenever there are conflicting symptoms or indications , it would be best to recheck the positioning of the thermostat in the housing. Boiling fluid in the reservoir indicates that the heated fluid has no heat outlet (radiator) , so the fluid keeps heating up until it boils. You should also be replacing the overflow reservoir cap because it is vented (@16lbs) , so if that cap's rubber seal or pressure spring is not working properly , you have no blow off (which , since it is boiling , should already be occurring).

    If nothing really makes sense , you should check that you are using a full fill of the correct coolant/antifreeze. With the all aluminum 3.5L engine , the service manual strongly requires that the "yellow" (not green) coolant is used at all times and not mixed (ever , unless it is an emergency). Aluminum engines , or even engines that only have aluminum heads , must use "ethylene glycol coolant " - as opposed to "polypropylene glycol coolant (which is green etc. for cast iron and steel engines only). Mixing these 2 is not acceptable according to the service manual for the 300M , and even if you do , you MUST flush and refill ASAP. Aluminum requires special protection , while all of the engine's other components and calibrations are set in accordance with ethylene glycol (IE : thermostat / gauge / radiator / hoses / heater etc).

    The last factor is the coolant mixture. I never buy 50/50 mix coolant , because I don't buy water , and those premixed containers are for immediate topups only. When you buy 100% coolant , you mix equal amounts of water in another container and fill from that (50/50). From there , you check the interior temperature gauge and adjust accordingly : if too hot , add coolant , if too cool , add water. Try to add 8 ounces at a time until the gauge balances just under half way. This can be a bit tricky too , when you don't really know if you have a 50/50 mix to work with. I always start by using the rule of thumb that "water" has a much lower boiling point than any coolant. From there , I know that the fluid will boil if there is too much water , or NO coolant at all - BUT , it is possible for coolant to boil as well. If you were to fill your vehicle with coolant only , once the coolant reaches it's higher than water boiling point , it will boil to where it will cool alot slower (take more time) than water. It can be a bit confusing to determine which way to go when you don't know about the actual fill. You can do so though , if you know that you can't run any engine strictly on water , as it will eventually overheat profusely. So... you could have either one of the 2 - too much coolant , or too much water.
  • After approx 8 months of trying to figure out why my 2000 to 300 M was overheating at high speeds on the highway or stop and go traffic but idling it was just perfectly fine. We then change the thermostat we also changed the water pump plus a new radiator....come to find out the OEM thermostats from Dodge/Chrysler are JUNK!!!! They have that rubber flange around them that does not sit correctly so we learned from my last car which was a 1998 Cavalier let's try a Failsafe from Autozone WITHOUT that rubber flange car runs perfect!!!!  Mind you this car has only 15,000 miles on a brand new motor that I did myself ....needless to say I may keep this pain in the tutu now...

  • After spending nearly $2,000 on fixes for our 2004 300M, the tech found casting sand in the coolant. It had collected at the thermostat. It overheated again and we had to clean the system again. Seems like a manufacturer's problem. I read this once before. Not sure how many times this has been the issue.
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