83 300CD 2-way Vacuum Check Valve?

83 MB 300 CDT
One drivers side vacuum check valve yellow three way. Vacuum source and two outlets.
The other check valve adjacent is yellow two way. Vacuum source and one outlet.
What is the yellow two way replacement?

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Diesel Engine Specific Aid

Chassis Model Number

W123

Confirm

What color is the vacuum line connected to the firewall side of this check valve?

Vacuum line color

Solid light blue.

Possible Seat Back Lock Circuit?

The CD models have a little bit different vacuum system due to the front seats. Not 100 percent sure but I suspect that blue line is going to lock the seat backs when the engine is running. Look under the front seats to confirm. We can't get a yellow one but we can get a black and white checkvalve is you are sure yours is bad.

Vacuum line sequencing

Shut down has been a problem.
Vac integrity checked by MVac.
Pump pulls 21 in at idle both engine and accessory vac lines plugged.
By error I reversed the engine and accessory lines to the main line. Accessory first and engine at brake boost shutoff valve.
Engine shutdown problem vanished.
I note in the 1980 vacuum schematic that the accessory line should be connected first and the engine control is a white orficed barb.
The orfice restricts vac as MVac will read 2 inches less white to unrestricted.
The accessory 5 way connect has a green with yellow stripe line.
Is that climate or cruise vac?

That is climate control vacuum source

green with yellow line

My errror

I looked at the schematic again.
The white banded orfice is for the accessories.
Back to the shut down issue.
Certainly worked well without the restriction.

Vac leak 83 MB CDT

1. The acc doors/locks, seat lock, climate control check, shut off ok with static MVac. Climate control test engine running shows a vacuum leak. Advice?

2. A black vac line running from the switchover valve to a three way and VCV has a line into the interior dash. What is the purpose of that line? It's open.

3. The seat back lock vac system has integrity but do not lock. Any advice?

Other: The two barbs on the main vac line are connected. The orfice restriction is on the barb closest to the Vpump and the 2nd accessory barb is banded white for 0.8mm, about the diameter of the end of a paper clip. Reverse flush of electrical parts cleaner resulted in flow out the barb closest to the Vpump. Did contain some residue.

Likely the switchover valves leak also.