1987 300 SDL with NO vacuum to the Blue saucer. So, this might be the culprit. What is it (so I can order it from Phil) and how do you test it (so I don't have to return it to Phil). Thanks for the help.

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a2


1978 280 CE silver
1986 560 SL black
1987 300 SDL cream
1994 SL 500 brilliant green
1997 E 300d dessert silver
2005 FORD F250 Superduty Crew cab 4x4

____ADMU____

That is your VCV ( Vacuum Control Valve ). I have a specific test for it in my service manual at home. I will try later this evening to send you the test procedure.
John

thankyou thankyou thankyou!!

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a2


1978 280 CE silver
1986 560 SL black
1987 300 SDL cream
1994 SL 500 brilliant green
1997 E 300d dessert silver
2005 FORD F250 Superduty Crew cab 4x4

____ADMU____

How do I test VCV? It's not producing any vacuum to the Blue Saucer and thus not providing any vacuum to the AT.

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a2


1978 280 CE silver
1986 560 SL black
1987 300 SDL cream
1994 SL 500 brilliant green
1997 E 300d dessert silver
2005 FORD F250 Superduty Crew cab 4x4

____ADMU____

Check the lines from the vacuum pump to the VCV then from the VCV to that amplifier. There are check valves that might be stuck or installed backwards.

Sixto
93 300SD

The VCV basically tells the transmission how to shift when the engine is cold or warm. At coolant temperatures below 50 degrees Celsius it increases the amount of vacuum available at the vacuum modulator of the transmission so the transmission will shift smoother when the car is cold. On the old 617 engine cars, the trannys used to shift really hard when cold. At 50 degrees Celsius and warmer, it decreases the vacuum to the vacuum modulator at the transmission and then the transmission will shift a little firmer.

Testing the vcv:
disconnect black/red vacuum line from the vacuum damper, and connect a vacuum gauge and check the vacuum at idle. Value should be 385+or- 20 mbar. with the engine stopped and the throttle linkage at full load stop the gauge should read 0.
if it tests ok proceed on.
not ok; check the vacuum pump or adjust the vcv and replace it.

Testing the temperature switch:
at coolant temps above 50 degrees celsius the ground connection for the vacuum amplifier switchover valve must be opened by the temp. switch.
connect ohmeter between temp switch and ground. value is Infinity. If it is not replace the temp switch.

Testing the switchover valve:
Unplug temp switch and ground the plug. The switchover valve should audibly click.If it clicks the switch is fine. No click, check if you voltage at the plug. If you have voltage but no click, replace the switchover valve. No voltage, you have to trace the wire to see why there is no voltage.

Hope this helps.
You can purchase a repair CD for your car from MBUSA for about $20.00
It has all the adjustment instructions for the vcv there. You really need to see the diagrams also when you try to figure out what is wrong.
Good Luck
John

thanks alot!! As a matter fact, I figured out what the problem was. I backtracked to the vacuum pump and the vacuum dissappeared at the "double T" connection. I believe there is a leak somewhere in the EGR portion of the system.I then bypassed the egr connections and connceted the vacuum line straight to the VCV. In the process, I replaced all rubber and plastic vacuum connectors _ (a whopping $4.00 for parts) and finally attached the vacuum gauge post vacuum amplifier(blue saucer). It started pulling vacuum to 12 inches! I was smiling to say the least. With this, I "T" from that connection and connected the remaining line which is the transmission modulator. The car shifted perfectly! Thankyou so much for all the help and suggestions. This is one awesome site!

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a2


1978 280 CE silver
1986 560 SL black
1987 300 SDL cream
1994 SL 500 brilliant green
1997 E 300d dessert silver
2005 FORD F250 Superduty Crew cab 4x4

____ADMU____