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1971 Mark III Temperature Questions

Bill,

I have a 1971 Lincoln Mark lll with original mileage 61,500 and original radiator. The car operates OK temperature (half way mark on gauge) at highway speed, however at in town stop and start or a little slow traffic it tends to overheat.

I checked it with a laser gauge at several locations and it checked at 220 to 225F at idle.

Please advise standard operating temperature, also is there a larger radiator available for the Mark III?

Any help with this is much appreciated.

Best regards,

Gene

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Greetings Gene -

Using a laser temperature gauge is a nice idea but we cannot rely on laser temperature readings to decide if an engine is overheating. To use this method correctly one would need to compare all of the readings and reading location areas with a similar engine that does not have an overheating problem. There is also no published correct laser temperature readings for a technician to compare with. The owners manuals and shop manuals usually point out where the temperature needle on your instrument cluster should read at certain times and and driving conditions. Many times a normal elevated reading is misinterpreted as an overheated engine. Your concerns of overheating of course are very valid and should be carefully and correctly verified. At Lincoln Land we would carefully check out your important cooling system components as follows. Your 71 MK III should be equipped with a seven blade cooling fan and the thermostatic fan clutch behind the blade MUST positively engage this blade on the warm and hot days at idle and low speeds as necessary to pull large amounts of air through the radiator. These two components are many times overlooked or NOT diagnosed correctly. The original three pass radiator in your car is of a capacity that will handle any driving condition in North America. If it was ever replaced with a lesser capacity rad. or if the possibility exists that it could have some blocked passageways it must be removed and properly serviced by a good known rad. shop. Always choose your radiator shop wisely as we have found that while there are many excellent ones out there, sadly some poor quality shops can do more harm than good. Of course the rest of the cooling system should have a good history of maintenance and coolant flushing etc. and the correct working engine thermostat and radiator cap should be in place. A small overlooked item such as a faulty rad. cap can spew coolant from the cooling system and give the illusion of an overheated engine. Good luck with your diagnosis and if you have any further information to provide us regarding the situation please let us know.

Sincerely,

Bill