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W126 Monovalve repair

126 Monovalve Repair

So there I found myself, driving around with intermittent heat. Fine around town, but as soon as I hit the highway - freezing! I thought it odd that if I was going faster, and the engine running hotter, that I would lose all heat. It would not just cool down, it was completely gone.

I surfed the news groups and read up a bit ( and the general consensus was: "Need to replace the Monovalve." I even found someone else that had the same symptoms - Heat in the city, no heat above 50 mph, and heat did not return when you slowed, you had to re-start the car to get any heat once it had gone out. The Fix - New Monovalve.

Repair is is so easy, it takes longer to put together this WWW page than the repair.

The Monovalve is the sensor/valve that allows coolant from the engine to get to the heat exchanger. As I understand it, it is the gateway to engage the heat exchanger to allow some of the engine's warm goodness to be shared with the occupants of the vehicle. I bought mine at the local dealership here in Salem for $36.00 (Note, this is for just the 'insert' not the whole valve assembly.) But then again, I really don't know. I am a lawyer by trade and many will agree that being a lawyer makes one generally incompetent.

Where is it: Between the firewalls and next to the battery. See the arrow in the lead photo on this page, as well, the below side view.

Unplug the electrical sensor

Unscrew the four screws holding it it place.
Carefully lift the whole assembly out

Remove the insert and replace with new insert. Keep your washers and rings in order. Put it all back together.



Note: This WWW page should not be relied upon for anything more that entertainment. The Author, Carl D. Crowell has no real competence in the field of auto repair, and many will argue that my lack of competence extends well beyond the arena of the automobile.

Please be kind, Rewind.


Used with premission, Copr. 2000, Carl D. Crowell

splitvalve.jpg removeconector.jpg sideview.jpg monovalv.jpg aux1.jpg aux2.jpg underhood1.jpg assemblyincar.jpg oldandnew.jpg

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