I have a 2001 300m. I have replaced the thermostate, waterpump and had it pressure tested. The car can sit and idle for 30 minutes without overheating. As soon as I drive about 30 miles on the freeway it starts to overheat. Any ideas?
My 99 300M has had similar problems. From what you describe it sounds
like you might have an air lock in your cooling system. I would
recommend that you bleed any and all air out of the cooling system. The
bleeder valve is located on top of the engine. Once engine starts to
overheat or when you can hear bubbling back into the overflow bottle,
turn car off and open bleeder valve. If you see bubbling you have air
in your system. Bleed the system a couple of times and see if this
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Re: 2001 300m overheating problem.
When the vehicle overheats, do u check the water/coolant level in the radiator? If it has reduced, it means ur leaking and u should inpsect to c where the leak is coming from. If the level has remained the same, probably ports are blocked or something to that effect. Keep me posted though
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From practical experiences of heavy trucks, this problem is created by poor coolant flow thro' the Radiator Core. Flush cleaning the Rad. or decontaminating the exterior air flowways will not cure the problem. My recommendation is a Recore or after market replacement.
try the water pump - first - make sure the radiator is really full - take the cap off cold and fill - if it looks full - start and run 8 minutes or so - then fill it up - look at ur fan belt - is it tight - tight is about how much pressure u use to make a firm hand shake with little movement - any movement over about an inch is loose - when the jeep warms up the belt can slip and not even make a noise - - new materials don't always squeal. - then be sure ur water pump is ok - they go slowing - the fins wear down - one more thing is the radiator - u don't say how many miles or what maintenance schedules you have or not so that's it for now
First place to look is the thermostat. When a thermostat fails, it prevents additional coolant from entering through the reservoir. Coolant backing up into the reservoir is another symptom of a bad thermostat. The reason you don't experience overheating when you drive is sufficient coolant is being pumped through the system by the waterpump.
Head gaskets don't cause overheating Usually they are a result of overheating. If the headgasket is bad one wil get leaking into the cylinders of coolant,which wil show up as milky oil.Like some one else stated ; have the radiator rodded out,(cleaned and fluashed).
if you have a blown head gasket you would have a miss
the waterpump can look good and still be bad
after you replace the thermostate fill the radiator and leave the cap off start the car let it get too operating temp and check for flow if you have good flow shut the car off and and put a pressure terter on the raidator this will tell of and leaks
here is a check list for common overheating issues
A headgasket leak? To test that use a coolant mix tester.
Do the cooling fans run with the engine hot?
Is the rad cap holding pressure? This can be tested usually its easier to swap it with a working one or buy new.
Lastly the waterpump and timing belt. If the timing belt if old/high mileage or the tensioner faulty it can cause overheating. The common practice is to replace the timing belt every 100,000miles along with the waterpump and the belt tensioner