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96 Lincoln TownCar Rapid overheat and cool

Hi There! Here’s hopefully an interesting one for ya.

I have a 1996 Lincoln Town Car Limousine. I am a novice with ford engines - but I am fairly certain its got ford’s biggest v8 they made at the time…its got a lot of car to move! It’s not in the greatest shape, but it runs and drives, so my friends and I use it for road trips and nights out, etc.

Recently we took it on its first big road trip - 800 miles round trip. As we were on the freeway about 100 miles into the trip we started having some overheating issues. But it only happened once, and we stopped at a gas station and realized we needed to add some coolant, so we did that and had no issues. I should note that we live around the Rockies, so we climb several mountain passes that are steep enough to have runaway truck ramps, and 65mph speed limits, warning signs, etc. We did not overheat once after adding coolant.

On the way home, the car suddenly started to constantly overheat over the redline, even when we were on flat ground. When it overheated, the temperature gauge would skyrocket in less than 10 seconds, after we took our foot out of it, it would fall right back to normal operating temperature, in less than 10 seconds. After it did that, it would be OK for another 30 minutes, and then do it again, or whenever we went up any kind of hill. So we went ahead and changed the thermostat in the car roadside. Checked coolant levels, they were not low. Kept going and it was OK for a while, then it started bouncing to super hot, and normal again - same issue as last time. However, it climbed the steep mountain passes alright, the temp bounces were much more frequent and we had to go really slow, but we made it. I have no idea what is causing these large temp fluctuations, outside temps the whole trip were well below freezing.

I should also note, every time the overheating issue was about to happen, the heaters would suddenly go cold.
It does not overheat when driving in town at all.

Any ideas on what I should be looking to replace?

Sounds like it could be an air bubble in the coolant system.


You have a coolant leak of some kind. When the coolant gets low enough enough air has entered the cooling system that there is air in your heater core instead of the hot coolant that transfers heat to your heater. Air also won’t transfer he to cool the engine. and when the level of coolant gets below your temp sensor it will make your gauge fluctuate wildly.

It could be as simple as a loose clamp or a hose that needs replacing, to a radiator that is leaking or clogged, bad water pump or worst case bad head gasket, cracked head or block or on some Fords leaking intake manifold.

Take it to a good radiator shop for diagnosis.

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I “liked” both of the replies above. My first thought was air pocket. Then the other post reminded me that you were originally low on coolant and must have a leak somewhere introducing the air pocket. Should be relatively easy to find the leak. Unless it is the head gasket / worst case screnarios mentioned.

Hi guys, thanks for the ideas. I definitely can understand having a coolant leak, or an air bubble. Does anyone know an easy way to “burp” the radiator in this car? This car is more like a fun hobby/just-keep-running type of thing that I really am not putting much $ into. I know that is only delaying the inevitable problem - but hey I got the car for free pretty much. :slight_smile: When we were driving the coolant never left the overflow tank - except at the beginning before I noticed it…so I feel like air might be a likely culprit that I should try to remove.

Thanks again for your insight!

Sounds to me like there’s a head gasket leak that is pumping exhaust gasses into the cooling system. One way to see for yourself is to start the engine cold with the radiator cap off, and the radiator filled. As the engine idles and warms up you may have to collect some spillover coolant and keep it away from animals (it’s poisonous) and if you see air bubbles breaking to the surface in the filler neck, that may be your air bubble leaving, but more likely it’s a head gasket leak. A shop with a hydrocarbon sniffer can sample the air above the filler neck and detect if there’s exhaust gas coming out - another indicator of head gasket leak or, far less likely, a cracked cylinder head or engine block. There are also chemical test strips to test the coolant for evidence.

Good luck and please keep us informed.