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?