Vacuum diagram 1972 W108 280SEL 4.5 - Mercedes-Benz Forum

 
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post #1 of 10 (permalink) Old 07-10-2013, 04:38 PM Thread Starter
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Vacuum diagram 1972 W108 280SEL 4.5

Can anyone direct me to a vacuum diagram for a 1972 W108 280SEL 4.5? I have several broken vacuum hoses which leads to nowhere. One in particular is a vacuum hose that runs along the top right side of the engine. Another is behind the battery compartment and two along the firewall. If anyone can provide me a photo of their W108 vacuum hose locations (door and emission) it will help me out considerably. Unfortunately for me, I seem to be the lone W108 owner in my area.
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post #2 of 10 (permalink) Old 07-10-2013, 10:47 PM Thread Starter
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Vacuum diagram 1972 W108 280SEL 4.5-img_5280.jpg

Vacuum diagram 1972 W108 280SEL 4.5-img_5281.jpg

Vacuum diagram 1972 W108 280SEL 4.5-img_5282.jpg

Vacuum diagram 1972 W108 280SEL 4.5-img_5279.jpg

Vacuum diagram 1972 W108 280SEL 4.5-img_5274.jpg
Here are some photos. Where do these vacuum lines attach to and what are their functions?

Last edited by wfd1; 07-10-2013 at 11:43 PM.
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post #3 of 10 (permalink) Old 07-11-2013, 07:05 AM
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Picture one is of a vacuum check valve. It heads into the driver' side inner fender, where the vacuum reservoir resides. I'd wager your door locks don't lock with vacuum, nor does your gas tank fill door. It's not required for the engine to run correctly, but it effects some convenience items.

The others (and I'm about 90% sure on this) are to the changeover valve circuit (changing air/fuel ratios once the engine is warm).

I'd LOVE to see a vacuum diagram too - I've never run across one and I've got a couple good manuals for the thing.
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post #4 of 10 (permalink) Old 07-11-2013, 08:23 AM
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the yellow two way valve is ignition retard cancel when a/c on , and also when engine temp is at 212 d . it connects to the trottle body , and the other to the distributor retard .the other yellow line should connect at a vacuum pipe at rear of intake , it should have a Y connector , and also to the vacuum tank under right fender .
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post #5 of 10 (permalink) Old 07-11-2013, 02:13 PM Thread Starter
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Originally Posted by Grubeguy View Post
Picture one is of a vacuum check valve. It heads into the driver' side inner fender, where the vacuum reservoir resides. I'd wager your door locks don't lock with vacuum, nor does your gas tank fill door. It's not required for the engine to run correctly, but it effects some convenience items.

The others (and I'm about 90% sure on this) are to the changeover valve circuit (changing air/fuel ratios once the engine is warm).

I'd LOVE to see a vacuum diagram too - I've never run across one and I've got a couple good manuals for the thing.
I suspected pic 1 was for the door locks. What threw me off was that the check valve did not have a Y connector. I do have a diagram for that but would appreciate if anyone has pictures to show me.
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post #6 of 10 (permalink) Old 07-11-2013, 02:17 PM Thread Starter
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Originally Posted by agillot View Post
the yellow two way valve is ignition retard cancel when a/c on , and also when engine temp is at 212 d . it connects to the trottle body , and the other to the distributor retard .the other yellow line should connect at a vacuum pipe at rear of intake , it should have a Y connector , and also to the vacuum tank under right fender .
That helps me a lot, thank you. I also noticed a vacuum hose running along the engine between the right valve cover and intake manifold. Any suggestion where this connects to? If you have any photos please post. Thank you.
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post #7 of 10 (permalink) Old 07-11-2013, 05:32 PM
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it goes from the electr vacuum valve that you show to the retard box on distributor
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post #8 of 10 (permalink) Old 07-12-2013, 08:45 AM Thread Starter
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it goes from the electr vacuum valve that you show to the retard box on distributor
Okay great. Thank you for your help. Do you know if that vacuum line has anything to do with idling? My W108 seems to never go down on idle. It stays at a constant as if it is constantly warming up.
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post #9 of 10 (permalink) Old 07-14-2013, 08:32 AM Thread Starter
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Okay, I traced the hoses to t retard and it seems as if the previous owner bypassed the vacuum device. The retard box from the distributor is connected directly to the throttle body. Should there have been a Y connector from the distributor retard o throttle body?
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post #10 of 10 (permalink) Old 11-30-2014, 12:04 AM
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Quote:
Originally Posted by wfd1 View Post
Can anyone direct me to a vacuum diagram for a 1972 W108 280SEL 4.5? I have several broken vacuum hoses which leads to nowhere. One in particular is a vacuum hose that runs along the top right side of the engine. Another is behind the battery compartment and two along the firewall. If anyone can provide me a photo of their W108 vacuum hose locations (door and emission) it will help me out considerably. Unfortunately for me, I seem to be the lone W108 owner in my area.
Were you ever able to figure out your vacuum system? I'm looking at a similar problem with my W108 280 SEL, plus the wiper fluid box is missing.

Was hoping for some pictures of a correctly set up vacuum system...Anyone got one of these technical marvels?
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