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90 420SEL 240,000 miles strong
557 Posts
Discussion Starter #1
Hey guys, its getting cold in Michigan. My 1990 420 SEL heats, but not as well as I like it too. Here is what I do know:

*Mono valve is not torn and does function, as well as the auxiliary water pump.

*Coolant lever is ok, car maintains a 80C all day long. Feels like the car takes a long time to warm up though, alot warmer than my other cars (Ford Temp, Grand Marquis).

I get air flow from the defrost vents (all of them), and the floor vents. No airflow from the AC vents or anything else. The recirculate door also functions (noticeable airflow change when you press the button)

The heat just really isnt as hot as other vehicles I have driver, including all 3 of my past 126's. Its OK, but Im a guy who likes his car super toasty. I flushed the heater core with water during the summer and this really didnt change hardly anything. The hoses feel equally hot as well.

Would a citric acid flush be next in line? Where would you get citric acid powder? Thanks in advance. What kind of temps do you guys typically get at the vents (if anyone have ever checked before)
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