QuestionQUESTION: Hi Roland my Concorde 1994 3.5 Liters is overheating strangely, at least i think so, i have read similar questions around the site but i want to be sure first if i have an abnormal problem. So this is what is happening:
My car started overheating 1 week ago, i bleed the cooling system as described in other answers, then i let the car idle in parking for about 2 hours and the car wont overheat, i mean when the temp gauge reaches the correctemp the fans start and then the car cools down normally doing this over an over again without overheating, but when i start driving the car for about 10 miles the cars starts to overheat i mean the cars cool down 1 or 2 times normally but then starts overheating, bubbling sound comes from the cooling reservoir and a lot of esteem is present when opening the bleed valve, so i can not use the car for more than 10 miles because the cars start overheating. I changed the radiator cap because the former one was damaged then the car was working perfectly for about 6 days no overheating present, but then my problem is starting again, the oil dipstick has no sings of coolant, when i started it in the morning normal white smoke comes out of the exhaust i mean barely visible, can i have a clogged radiator, one side of the radiator (plastic side of it) (the passenger side ) is very hot, the other side is warm, there are no leaks that i have detected, can i have a damaged water pump or a head gasket damaged? i mean the car idle does not overheats. Also sometimes the low oil light comes and the oil level is fine, i havent changed the oil filter since maybe 1.5 years Thanks you very much!!!"
ANSWER: Hi Hector,
The fact that it operateds normally at idle for long periods of time suggests that the thermostat is working, the water pump is working, the fan is working and there appears to be no leaks nor head gasket leaks. My thought is that the coolant cross-flow (and perhaps too the air flow from front to rear through the fins) of the radiator from the passenger side to the driver side is partially clogged with debris/corrosion that has built up over the years. When you drive the heat output of the engine goes way up and with a reduced ability to dissipate that heat at the radiator the coolant overheats.
It would be good to put a light behind the radiator and look through the air fins through the grille openings to verify that dried dirt/leaves aren't clogging the air flow.
You might try a heavy duty radiator flush out to see if that would improve the rate of coolant flow across the radiator. If those don't solve it, then replacing the radiator would be the next step. If you do that yourself it should cost more than $150 for the job. If you need an instruction sheet on how to remove and install the radiator let me know a postal mailing address and I will xerox and postal mail you a copy from the service manual.
Roland
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QUESTION: Thank you very much Roland, i will check it out, as an update i changed the thermostat, i replaced the coolant deposit cap, and one year ago i replaced the radiator and never added coolant only plain water, maybe has some dust or dirt in it, so to be clear both sides of the radiator must be at the same temp? because the hot side is where the hot water enters the radiator and the cooler side is where the cool water leaves the radiator well i think that so i want to be sure of that and the take the radiator to be flushed, here at Mexico that costs me $10 bucks. i will do the light test to check the radiator. By the way i noticed today that the engine is loosing oil from a leak and i have no oil in it!!! can this cause the overheating as well?
AnswerHi Hector,
No, but if the output side is really cool it would make one suspect that the cross-flow is impeded. But with such a new radiator it is probably the case that your radiator is fine. The cold/hot side difference is more relevant with a radiator that has inlet and outlet hoses on the same side, a double cross flow design. On the LH/Concorde it is only straight across once.
But when you tell me that you are only using water, that makes me wonder if your problem is simply that the normal operating temperature, as designed, is too high to allow for water only as the coolant. Chances are that in the engine proper the temps will get high enough to boil even when the system is pressurized. I suspect that if you will simply drain out 6 quarts of the water, put in 6 quarts of 100% antifreeze (to make a 50/50 mixture which is optimum) that your problem will be solved. Of course, bleed out any air as before.
So try that first, and if that isn't the answer, then a flush. The boiling point of a 50/50 mixture is up around 265F as I recall, compared to 212 for water. Buy the extended life type anti-freeze, orange in color, as it will be cleaner running and require less frequent changing.
I doubt a modest oil leak would affect the cooling of the engine.
Roland
