300m running 'hot', looses power at 60+

Last Edited By Krjb Donovan
Last Updated: Mar 11, 2014 07:46 PM GMT


QUESTION: Hi Roland,

I had the mechanic run the test on the head gasket and he said it is good..no leaks. But he said I will probably need a new water pump, since there is no heat in the cabin and the engine keeps running hot.But it hasn't run hot since I added the stop leak, but it does run hot if I stay idle for some time. Does this sound right to you? I also ran the brights to get rid of the moisture in the headlights. It worked thank you! I also noticed a drag when you try to pick up speed, its riding pretty hard when I go above 60, could this be because of the water pump?..thank you so much for your time. Nicole


My answer to the current question:

Hi Nicole, I an not certain about what you are describing. Are you loosing coolant now such that you have to add it regularly, or is there no sign of coolant loss at all? May I ask what you mean by "it does run hot if I stay idle for some time"? How high does the gauge show when you let it 'stay idle for 'some time', and how long do you leave it idle before it reached that reading in the gauge? May I ask the year and engine size (L) of the car? I am not sure why the mechanic thought the pump was possibly in need of replacement without there being sign of leakage. Did he say it was the only reason that would explain "running hot"? I wonder about other possibilites such as a fault thermostat or a partially clogged radiator which should be considered before the water pump which is much more expensive repair. The thermostat is easy, the radiator is fairly easy and mainly the cost of the radiator is involved, in comparison to the water pump which is a big job! The performance of the engine on the road is independent of the water pump unless you are running on "H" on the tenmperature gauge, so I would suggest that you take your ignition key and do the following: turn it "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the instrument cluster odometer window to see the milege reading disapper and in its place a 4-digit number(s) preceded by a P. Let me know such number(s). I will await your response with interest. Please "rate" my answer as you so kindly did previously. Roland Prior question history:

I have a 300m it was running hot then I had a leak, so I put some stop leak in it, that has stopped the leak, but I fear this is only a temporary fix. Also I have no heat until I put my foot on the gas and the driver side headlight has moisture in it, the light still works, but it has condensation in the cover. Since the winters here are brutal I really want to get it fixed soon, but since I'm a woman I want to go to the mechanic with some understanding so I don't get beat. Could you also tell me what's a good price range for the repairs?

Your advice would be greatly appreciated.


ANSWER: Hi Nicole, If the leak was in the radiator, near the headlamps, then that might have added to the moisture buildup in the headlamp housings. That leak problem is ideally fixed now. Some moisture accumulation inside a vented headlamp unit is normal. Moisture will vent from tubes or vents located on the back of the unit. This normal condition will appear as a fogging on the inside of the headlamp lens (similar to the fog that sometimes appears on the inside of the windshield). This moisture may be removed by activating the headlamps on high beam for 15 minutes (while driving during the daytime).

If water droplets larger than 1 mm in size have accumulated on the inside of the headlamp lens, the headlamp unit should be opened (remove the bulb or discharge unit) and allowed to dry out in the sun or other heated situation. If that doesn't solve the problem it may be necessary to replace the headlamp unit, but that is doubtful if there are no signs of damage to the housings. I suspect that the 50/50 mixture (ethylene glycol/water) of leakage from the radiator will be more difficult to evaporate away but I believe that if you will drive on high beams for 15 during the daytime, for several days in a row, you may evaporate the buildup in the housings. Please 'rate' my answer (see below). Thanks, Roland

---------- FOLLOW-UP ----------

QUESTION: Thank you so much Roland!!! and I do what you have advised. Just so I am clear about what you are saying - the overheating will stop since I added the stop leak, but its over heated since adding the stop leak, and I've had to add stop leak twice in two weeks. A friend told that since the car was overheating I would probably need a new water pump or radiator, which both sound pretty costly to me and if that's what needs to be done then I will, but if there is any other options that I could try before spending a large amount of money, please let me know. Also what should I do about the heat, since it only comes on sporadically, mostly after I have driven for a while, but other than that it takes about 20-45 minutes before you start to feel heat. Again I really appreciate your help! Nicole

ANSWER: Hi Nicole, It sounds like you are loosing coolant consistently and so the question is where is it coming from in the system. Have you seen coolant on the ground under car or inside the engine compartment? Or is it mainly appearing from out of the coolant recover bottle lid when the engine is moving toward the "h" on the gauge? Do you see excessive white smoke coming from the tail pip when you first start the engine from cold? Do you see water leaking from the front of the engine or from a coolant hose? Are carpets under the dashboard wet? Somewhere there will be a clue as to where and why you are loosing coolant and then we will know what specifically to do next. Don't just throw parts at the situation before a proper diagnosis is done. Roland

---------- FOLLOW-UP ----------

QUESTION: Yes, I am loosing fluid..I have gone threw about 4 bottles of fluid in the past two weeks, and now before i leave or start the car I check the fluid to make sure there is some in the coolant container. and if its low i fill it back up. The leak stopped but it was on the front passenger side. Since the second bottle of stop leak, it hasn't been leaking, but now i have a bottle of it in my truck just in case. Yes there is white smoke coming from the tail pipe, however I am not sure if its excessive, I don't have a cloud of smoke but I do have some white smoke. The floors and dashboard are not wet. So should I take it in to have a diagnosis performed from a mechanic? or is this something i can do myself?


Hi Nicole, If the leak you saw on front/passenger side of the engine is definitely no longer present after using the stopleak, but you are nonetheless still either having an issue with higher than normal temp gauge readings, more than usual (in the past in comparison) white smoke from the tail pipe, then you may have also a head gasket leak. That would also be notiecable if within 5 or minutes of starting the engine and you open the hood and listen you should happen to hear bubbling sounds from the radiator/engine/coolant hoses as those noises would be a sign of such a leak between the combustion chambers and the coolant system. That can be checked quickly and inexpensively at a radiator repair shop by asking them to check for the presence of exhaust gas in the coolant system which is the most sensitive test for a head gasket leak. Tell them the history and let them test and look for the cause of your problem. If the problem is very expensive to fix ask them how sure they are of the problem and also let me know what they tell you before authorizing the repair. It may simply be a faulty thermostat for example if the engine is running hot but without any loss of coolant. But the lack of cabin heat makes me think that you are loosing coolant from the system and the flow of coolant through the system due to exhaust gas bubbles in the system may be indicative of a head gasket leak. Ask friends for a recommendation of a good radiator shop. Please 'rate' my answer (see below). Thanks, Roland End of history.

---------- FOLLOW-UP ----------

QUESTION: since i added the second bottle of stop leak it hasn't been leaking and I check the fluid everytime I go anywhere and so far since I added the 2nd stop leak it hasn't ran hot.. but the gauge stays between the middle line when I drive some times it drops just below the middle line eon the gauge, so this i is why i think its still running hot. I usually only takes a few miles before the gauge is on the middle line. If I'm at a stop line or just stopped in traffic the gauge tends to creep up just above the middle line on the temp gauge, that's why i said its running hot when i sit idle.

The car is a 2001 300 m not sure what engine size it is.

Yes the mechanic said that's the normal reason why they run hot, but i haven't made an appointment for repair, I wanted to get your thoughts first..should I take it to someone else?

I'm gonna go out side now and try the key procedure now and Ill get back with you shortly.

What I meant by drag is the other rpm meter goes above the 2 whenever I try to go take off or if I'm driving on an incline.


Hi Nicole, The gauge is reading absolutely normal! You don't have a problem with the system unless it consistently operates between the 3/4 line and the H. A range between 1/4 and 3/4 is perfectly fine. As to heat, it may be that you simply have some air trapped in the cooling system part in the cabin which is impairing the flow of hot coolant so you don't get as much heat. Tell me the engine size and I can send you a page that shows how the system should be drained partially and then refilled so as to get rid of that trapped air if that is the cause of low heat. Tell me the numbers if any that you get. It is normal for rpm to jump when you step sharply on the gas for acceleration when going above 40 mph. That is built-in behavior of what is called the "torque converter lock-up" which is unlocking when you do that action. The lock up feature improves mileage but it is defeated when you acceleration fast. Roland


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