QuestionI have a concorde that that I have replaced the waterpump, belt, tensionor, 2 caps for the radiator, therm twice, radiator pressure checked ok, and fans and relays checked good.
The car will drive 20 minutes, and will then start to overheat. I loose my heat, and get a huge amount of air in the system. All of the coolant goes to the reserve, and will not leave. If you turn off the car, it cools off within minutes, but as soon as you drive, it overheats again. Where could a blockage occur that I am missihg? please help.
AnswerHi Amy,
You said the radiator pressure checked o.k., but I'm not certain whether that means it just isn't leaking or if it also checks for the quality of the flow across the radiator. When it heats up as you describe, carefully feel the two outside edges of the radiator if you can touch them behind the fan assembly to see if both sides are at least warm, if not hot. Touch quickly and lightly to avoid a burn. If one of the sides is cool it might mean the coolant passages running across the radiator are blocked, but with such a new car I would doubt that the radiator is gunked up enough to cause this sort of behavior.
On the other hand, the remaining explanation is not that happy to consider. It is sounding to me like there is a head gasket leak in one of the two sets of cylinder banks that is allowing exhaust gas to enter the cooling system (thus the source of "the huge amount of air" that drives coolant into the overflow container. And because the cooling system has an escape pathway (backwards into the cylinders) it will not develop a vacuum as it cools so as to pull the coolant back from the overflow bottle. It sort of hangs together as an explanation, to me.
One way to detect such a cylinder head gasket leak is to notice whether when you start the car from cold (and having refilled the radiator earlier to make up for any losses) does a lot of white smoke come out the tail pipe? If you let the water vapor which is what the smoke consists of condense on your hand it will smell of antifreeze if indeed this is the case. The white smoke lasts much longer than routine condensation on the exhust pipe innerds, and it is noticeable. Another way is, at a radiator repair shop, to have them put an exhaust gas leak testor on where the radiator cap fits and this device can sense exhaust fumes if they are present in the radiator (which they shouldn't be if the head gaskets are o.k.)
If you have such a leak, then the cylinder head has to come off and a new gasket put in. You can identify which bank of cylinders has the leak via a compression test or by simply removing the spark plugs and looking for a wet one. It should be a repair that is covered under warranty unless the mileage limit of the original warranty has been exceeded. If you are going to have to pay for the repair it might be worth a try to get the leaky gasket to seal by re-torquing the head gasket bolts and/or putting in a sealer like Bar's Leak. I have had success with re-torquening on several engines, in the past. The Bar's Leak is not a permanent fix in most cases, but a stop gap.
So look into those two possibilities as the most likely remaining causes of your problem. And please let me know what you observe.
Roland
