Hi,

Going to do a flush of the cooling system...

I'd like to put the garden hose on and run it through the heater box to flush it out, but need some help identyfing the return outlet hose from the heater box so as I can crack it open to get the flow happening.

In my picture below I have marked three hoses coming off the mono valve and one that goes into the mono valve, which originates from the block/thermostat area.

If I attach the garden hose to the hose which originates from the block and then turn the controls to full heat, that should get the flow happening but can I crack open one of the other three hoses to get flow really moving?

Reason I'm asking this instead of just cracking all hoses to work it out myself is because the mono valve plastics are decaying, so I'm trying to avoid disturbing things I don't need to, and also avoid an expensive mono valve replacement if I don't need to.

Thanks

Attached Thumbnails

 

__________________
1995 E300 Diesel

Couple thoughts.

Does the car run? If it does turn the heater on and see which hose gets hot first. That will be the supply. Don't forget to let it cool down before you start disassembly. I would just flush both ways through the heater core if I was doing it. The passage ways are pretty open on it.

In regards to the monovalve if you have a breaker yard nearby try to grab the monovalve from any of the early 90's MB's that had them. They won't be like the 95 E300 but you can mix and match parts as needed. The main thing is to not let the body of the monovalve get messed up. It may be a single year design - not sure. Not sure which all monovalve bodies are just alike but there are similarities between them.

__________________
Jim

All hoses on the (right) passenger side are HOT water INLET.

The DRIVER side hose is the OUTLET, return from heater core.

.

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Thank you whunter.

I presumed this was a drain of some kind. Makes sense now.

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1995 E300 Diesel