I need to replace the thermostat and water pump in my 1980 Mercury Zephyr, a 4-door sedan with an inline 6-cylinder engine and an automatic C4 transmission. When I got the car in 1999, the odometer read about 60,000 miles. Currently, it reads about 140,000 miles. Most sources recommended flushing the system before installing the new thermostat and water pump. A mechanic noticed that the freezer plugs on the engine are heavily rusted. The freezer plugs will be hard to access and replace. Someone thought I should be cautious in flushing the coolant in the engine with an engine flush (such as the Prestone brand) because it could lead to the rusted freeze plugs rupturing. Should I still flush my engine, radiator, and heater core? If so, what would be the best method for my vehicle? Any advice would be greatly appreciated.
Yeah I kind of agree with something Rusty like that. I would just remove the thermostat and just use a garden hose to flush it out
Follow this video. I bought a shop vac specifically for this purpose after I saw Scotty do it this way. I changed the coolant and thermostat in my '79 Catalina a few months ago. I didn't use Prestone cleaners. They're a waste of money in my opinion. Garden hose and shop vac works well.
Thanks a lot Scotty and Justin.
Respectfully,
Tim