1988 Town Car Engine Rattle

Hi Bill,
I have a 88 Lincoln Town Car …. Love it !
The problem I have is a little bizarre… When the engine gets hot, the engine rattles like hell. It almost sounds like a card in a bicycle wheel spoke. I have owned many cars and trucks and have worked on them all, but have never heard anything like this.
When the car cools down ….. it’s like nothing ever happened. I have changed the water pump, thermostat, and cooling lines. My next step will be to flush the coolant system. My mechanic mentioned a retarding system in the ignition to help cool the engine down, but I have never heard of this… Any suggestions? I’d love to hear some.
Thanks,
Bill
Upstate NY
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Greetings Bill –
I have not heard of a noise such as you are describing as many strange sounds need to be heard in person in order to try to diagnose them correctly. You also do not say if the noise can be heard only at idle or while driving. From your letter though you seem to believe that it is making this sound only when hot and that the engine is overheating. An overheated engine can indeed make strange noises and should be repaired ASAP. if it is in fact overheating.
Not knowing the maintenance history of your car two important items to consider are the Thermostatic Clutch on the engine cooling fan and the Radiator itself. This clutch unit is well known to fail and many technicians have been fooled by a cooling fan that appears to be cooling properly but in fact is not turning fast enough as designed because of a bad clutch. Your Lincoln is also old enough at this point to possibly have a radiator that is partially plugged enough to cause overheating. A radiator that is thought to be in a plugged condition would need to be disassembled and cleaned or re-cored. I am not familiar with a retarding provision on that vehicle help to cool the engine.
If the above does not appear to help and if you can provide us with some more information we may be able to help with further advice etc.. We do have parts on hand that you may require so please feel free to contact us at your convenience.
Sincerely,
Bill