Visit the Lincoln Mark VIII Forum for more help
Replacing the engine thermostat is pretty simple and easy.
The stock engine in the Lincoln Mark VIII Is the Ford 4.6L DOHC engine. This is the same engine that was stock in the mid 1990s Mustang Cobra. The instructions below are as if you don’t want to replace all the engine coolant, but I recommend you do a complete engine coolant replacement as part of this.
This works for all years of the Lincoln Mark VIII, from 1993 through 1998. This will also work on the Lincoln Town Car and Lincoln Continental of the same time period that have the 4.6L engine. If you have more questions about these cars, visit the Lincoln Town Car Forum or the Lincoln Continental Forum
WARNING! Be sure the engine is cool before attempting this. Automotive Coolant gets very hot when the car is running.
1. Drain coolant level below upper radiator hose and thermostat housing.
2. Disconnect lower radiator, coolant recovery and engine return hoses at thermostat housing, then remove two thermostat housing retaining bolts.
3. Remove O-ring seal and thermostat from thermostat housing.
4. Inspect O-ring for damage and replace if necessary.
5. Reverse procedure to install. Tighten to 7-8 ft lb .
6. Replace any missing coolant. Be sure to burp the cooling system.
Here is a video showing the process: