W108 4.5 Vacuum Line Source - PeachParts Mercedes-Benz Forum

Kisii · #1 05-02-2011, 08:41 PM

Hi All,

First of all to thank all the contributors for the resources on here...helped inspire my purchase of my '72 W108 4.5.

Trying to figure out how to replace this part. This is the line that runs from the master cylinder, and being a noob, I have no idea if the hose comes apart, we suspect that the leak in this hose is causing the rough idle and white smoke that have been the symptoms on my car. Scoured online parts websites and the like but didn't see anything that seemed like a replacement. Please put me out of my misery.

Thanks,

Sam

Kisii · #2 05-02-2011, 10:24 PM

Any known sources for the brake booster vacuum supply hose?

Tomguy · #3 05-02-2011, 11:15 PM

It may not be listed on the site, but I'd call Phil.
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Your other option would be to re-use the check valve (if it still is good) & fittings, and source hard plastic line from a thrid-party, using a heat gun to reshape it. It wouldn't cause white smoke. If your smoke is actually WHITE versus blue, check to see if your trans modulator has a ruptured diaphragm. Symptoms would be white smoke under heavy engine vacuum, such as taking your foot completely off the gas at 80mph.

Kisii · #4 05-02-2011, 11:42 PM

Thanks Tomguy, I was trying to get the hoses off and replace with similar, and managed to break the check valve. I don't know if its a good idea to piece it back together with silicone, and give it a shot with similar high temp power steering return hose. The w108 was my daily driver while my other car is in the shop, so desperation is checking in. Will call tomorrow thanks for the heads up.

meltedpanda · #5 05-03-2011, 09:15 AM

you can always ask the classic center , but the prices may scare you, the hose itself is nothing real special , just needs to be strong enough not to collapse on itself, use fuel line clamps on the ends and source the check valve. I have a lot of check valves lying about, let me look at my stock and see what I can find

Kisii · #6 05-03-2011, 12:24 PM

Thanks, got it at Peach Parts. Sometimes you have to know what to call what you are looking for, in this case a "Cohline" booster vacuum hose. Part No. W0133-1758803.

carnut · #7 05-06-2011, 12:55 PM

On my 108 4.5 the white smoke and rough idle turned out to be the computer itself going rich. there is a knob on the side of the computer that can be adjusted with the car hooked up to an exhaust HC measuring machine. With the rubber cover removed, you should see it. I adjusted mine 3 times and it still would act up. I replaced the computer and that fixed it. I confirmed the rich condition by smelling the dip stick which smelled like gas. Up till then, I thought rich would be black smoke but mine was white and smelled like raw gas. The hose comes from the booster not the master cyl. and if leaking would cause a very hard to push brake pedal. And put your year and type of car in your signature profile please.

Kisii · #8 05-06-2011, 08:02 PM

Thanks Carnut,

I received the hose and I believe it belongs on the 6 cyl engine...it seems longer than what should be on mine, the part number I sourced was W0133-1758803,...I could be wrong though.

Graham · #9 05-06-2011, 09:02 PM

Quote:

Originally Posted by Kisii

Thanks Carnut,

I received the hose and I believe it belongs on the 6 cyl engine...it seems longer than what should be on mine, the part number I sourced was W0133-1758803,...I could be wrong though.

To avoid that kind of thing, it's a good idea to sign up for the Mercedes EPC (Electronics parts catalog) It's free but they do ask for a CC number just to make sure you are in the USA! You can also access the Russian Parts Catalog, but it is not as good.

If you find the part number yourself before ordering, there is no-one to blame if you get it wrong

BTW, That number you posted is not a Mercedes number, more likely the vendor's number.

PS: I tried to quickly find that hose, but had no success. But did find that they sold the check valve and end bushing separately.

Kisii · #10 05-06-2011, 09:39 PM

Graham, it wasn't easy finding that hose, I'm actually signed onto EPC and submitted that number before I came up with that vendor number (Cohline). My installation is what gave me the impression that it might belong on the M130 engine...but apparently I am wrong, I got the right part, I think its my installation that is a bit awkward.

Tomguy · #11 05-07-2011, 08:47 AM

It looks like you have it on backwards. Make sure that the check valve allows air to flow from the booster into the manifold & not the other way around. The check valve on mine is close to the booster, not the manifold.

Graham · #12 05-07-2011, 08:08 PM

Quote:

Originally Posted by Tomguy

It looks like you have it on backwards. Make sure that the check valve allows air to flow from the booster into the manifold & not the other way around. The check valve on mine is close to the booster, not the manifold.

I think Tomguy may be right. The 108 engine is much like my SL,s engine. In the picture below, you can see the brake vacuum line at the back of the engine I should probably get a new one too - I taped mine up (black tape) where it has worn in one area.

Kisii · #13 05-12-2011, 01:45 PM

Thanks for the picture Graham. The hose did not sort out the rough idle, so I am going to try the suggestions on this thread

http://www.benzworld.org/forums/vintage-mercedes-benz/1368469-w108-idle-warm-start-problem.html

and see if I can work it out. I seem to remember that one of the fuel injector seals was not up to spec.

carnut · #14 05-12-2011, 05:54 PM

In my experience a rough idle on a fuel injected engine is usually because its being over or under fueled. too rich or too lean. Vacuum leaks normally just raise the idle, unlike a carb'ed car where the idle becomes erratic.

Graham · #15 05-12-2011, 09:04 PM

Quote:

Originally Posted by Kisii

Thanks for the picture Graham. The hose did not sort out the rough idle, so I am going to try the suggestions on this thread

http://www.benzworld.org/forums/vintage-mercedes-benz/1368469-w108-idle-warm-start-problem.html

and see if I can work it out. I seem to remember that one of the fuel injector seals was not up to spec.

Have you tried adjusting teh idle mixture screw on the ECU. It controls idle mixture and one click makes a difference.

But first make sure that the Throttle Position switch is set up properly. I think it is same as our SLs. I posted a pdf on this or the SL forum on how to set up the TPS. Just make sure the linkages are not preventing the TPS from activating the idle circuit.