How to reach inner engine valley on 107?

[Bondavi]

I need to check/replace the vacuum lines heading into the engine valley to the upper/lower plenum. What is the best way to reach into this area? Remove fuel distributor assembly, or? I am replacing a couple vacuum lines down there.

Thanks!

[Bondavi]

I confirmed that I have a broken vacuum line near the TPS (throttle position sensor) There is a group of three lines that go into a plastic sleeve, this one I think is a clear with red or orange. See attached picture.

My car passed the smog test except high NOx at the 25mph test. HC was borderline. I'm assuming this broken line is messing up the fuel mixture system somehow... What would this line connect to, normally? I don't see where there'd be a missing vacuum line connection.

So whats the best way to get to this area without disassembling the entire fuel distributor? I can see there are some screws I can take out and remove the CIS assembly as a whole and access the lower plenum. Any instructions to how?

Thanks!

[Roncallo]

The lines that go under the intake manifold all go to the throttle body. I looked at the possibility of removing my distributor to possibly reach into there and get them. I cannot confirm weather or not this will work. Otherwise it will require removing the intake manifold. If you are going to fix anything down there be sure to replace all rubber elbows.

A leak in one of these lines would cause a lean mixture which would cause a lean missfire and increase HC. I cant coment on NOx

John Roncallo

Last weekend I completed the overhaul of the intake manifold per the Pindelski site. On my 117.962 engine, there are 5 vac lines that run down into the plenum area. They are accessible after removing the fuel distributor. I inadvertently forgot to tighten the large hose clamp around the throttle body until I had put it all back together. Naturally, as soon as I tightened it, it broke. After a few choice words, I had to remove the fuel distributor in order to replace the clamp. It was not tough, but of course I had just done it and had the benefit of the learning curve. You will need to unsnap the throttle linkage on the right side, remove fuel lines to the injectors, remove the fuel supply and return lines by the brake booster, remove the 2 fuel lines to the warm up compensator, remove the fuel line to the cold start valve, remove the idle speed controller, and loosen the existing clamp on the throttle body. Then pull the fuel distributor up and forward by holding the rear part of the distributor. You will see three vac lines that connect to the intake manifold vent valve (on right side of throttle body) and two that plud right into the plenum by the throttle body. I made a sketch before I took mine apart.

Rich Mayer
82 500 SL

[Bondavi]

Ok I did it. In less than 2 hours, I got the distributor assembly out and tackled the lower manifold throttle housing. There is a vacuum switch actuated by WOT.

The lines that go into this switch are, according to the manual,

EGR valve
Warm up regulator - lower chamber
To 4-point distributor (what is this?)
To reservior for full load enrichment

The switch is broken off in one area, as you can see.

Where can I obtain a replacement vacuum switch like this?

Also I need to replace the fuel line coming from the fuel distributor into the warm up regulator.

Also how can I test proper operation of the TPS switch (throttle position switch) with a digital meter?

[Bondavi]

OK this thingy is called a full load enrichment/idle vacuum control valve, located at the throttle housing. Part #003-997-003-6

MB has this part for $60.00! I wasn't able to find anyone else that stocked this part. On order.....

You did the right thing. I ordered the same part last week. The 4-way you asked about is the 4-way rubber vac connector near the idle speed controller.

By the way, I have a few questions for you. My speedometer is inaccurate. Could you tell me the part # on your speedo face and whether it reads in mph or kph? Also, I read somewhere that there is no lambda control on the Euros and hence no pin 3 on the diagnostic plug. Is that true of your car? Is testing the exhaust the only way to check the mixture for rich/lean?

Rich Mayer
82 500 SL

[Bondavi]

Originally Posted by diqmayer

My speedometer is inaccurate. Could you tell me the part # on your speedo face and whether it reads in mph or kph? Also, I read somewhere that there is no lambda control on the Euros and hence no pin 3 on the diagnostic plug. Is that true of your car? Is testing the exhaust the only way to check the mixture for rich/lean?

Rich, my speedo face is "107 542 43 01". The car was changed over to a MPH gauge when it was brought into the USA brand new. It displays fairly accurate up until freeway speeds, where I'm seeing a 10% error. Are you getting this? My car has the AMG 17's so this might be a gear swap.

There was no Lambda control on the euro spec, mine was the aftermarket type. No worries, cuz I have since pulled it and all the wiring junk off of my car. Many MB experts said I'd be much better without it, and still being able to pass CA smog! However I have left the O2 sensor intact, and there is a way to test using a meter (analog recommended over DMM) and get that .05-.09 reading. There was a followup post to my earlier post regarding this topic.

Today my new Magnaflow 2" precats/main cat setup arrived....the car will go into the shop to install this new exhaust system, so between that and the repairs to the intake should be enough to get the last part of the smog passed. Looks like EGR wasn't switching on from the looks of this control valve I'm replacing here.

Anyway, hope that helps! Feel free to ask away if you have any more questions.

David,

Interesting. My present speedo face reads 107 542 66 01. When you say that yours was changed upon importation, what exactly changed? Just the dial or the entire speedometer instrument? When I brought my problem to the attention of MBUSA, the technical expert gave me an original speedo part number of 010 542 80 06 for the Euro 500 SL. Clearly, I have the US replacement. My question would be why can't I use the speedo I have, provided that is can be "connected" properly to my transmission. My trans is 722313 02 144600 according to my build card. So would the speedo part number above be useable with the trans # above? If so, with what part connecting the two? My kingdom for the correct answer to this question. By the way, the problem is not in the speedometer itself. I got a new one and the readout was the same as before. Thanks in advance to anyone who can answer.

Rich Mayer
82 500 SL