Morning all
1986/126.125

These are my heater settings...Automatic/on.Heat dial at Max.

Sometimes after first start of the day heater blower comes on but no heat, actually its quite cold but if I turn the engine off for a few minutes after restart it suddenly becomes hot.
I have searched all around for vacuum hoses disconnected but have found nothing.Now I'm thinking of the mono valve?

Has anyone experienced this?

Thanks
Big Dan

 

I am working on a no-heat issue also on my '83 126. She will have heat once warmed up and will keep it for in town driving. Once on the highway(65-75mph) it goes away but will come back briefly after stopping. In doing some research it can be the monovalve ,as you mentioned, or the aux pump that cause no heat issues (at least ones unique to MB). Along with the common issues like a partially clogged heater core (say this since you do get some heat). Was the heat working properly then went away? Have you changed the coolant and/or themostat recently? If a thermostat change, what temp is shown on the gauge ( does the gauge read properly and have you used an IR temp sensor to verify). Is the proper recovery tank cap (stamped 100) in place and in good condition? From what I've read so far the monovalve and or aux pump can cause a restriction of flow to the heater core. I hope my suggestions is of some help. This is my first MB and first diesel so it's a learning curve for me.