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Old 07-25-2008, 01:37 PM
timm9 timm9 is offline
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Join Date: Apr 2007
Location: Sierras, CA
Posts: 138
Problem Resolved (I think)

I (think) I have finally resolved my issues and thought I would post a follow up for the benefit of all. Hopefully this will save someone time and frustration!

First of all, I owe a huge debt of gratitude to one of the Moderators on this site. They have for all these past weeks since my first post, painstakingly helped, advised, educated, and dealt with all of my questions, inexperience, frustrations, etc. You know who you are and I will never forget you!

As you can see from the original post, I was dealing with high fuel consumption (11 MPG) and very rich fuel mixture. No matter what I did (at the direction of an extremely helpful and knowledgeable Moderator) the duty cycle/on-off ratio would not change and was running between 75/80%. I won’t go into all the details because if I were to post all of the things that were tested, retested, etc. this post would be a small book.

After everything that was checked, replaced (including a new brain see attachment), and rechecked, it appeared that I still had a large vacuum leak. After several weeks of coming home after work and spending hours each night trying to find the leak, I had reached a new level of frustration. Out of desperation I drove the car to a shop 50 miles away that had a smoke machine. After $100.00 for the smoke test the leak was finally found! The problem was well hidden below the Mass Air Flow Sensor and Fuel Distributor (see attached PDF item #14) and caused by what the CD refers to as the Air Guide Housing. As you can see in the picture (attached) there are no less than 6 large cracks with the largest being approximately 2 ½ inches long. There is no way to see the cracks without the smoke machine. After questioning the previous owner, I feel these cracks have been in existence for well over 15 years! Keep in mind that this car was inspected before purchase, and also transported the car on a trailer to a specialist in classic Mercedes. The second person did find injectors that were leaking but no one has ever found the cracks in the Air Housing Guide. I now have what I believe to be normal vacuum, and I still need to replace the Accumulator and get my Duty Cycle adjusted but it appears that the cracks in the Air Guide Housing were creating the high fuel mixture and poor mileage. There may still be minor issues to deal with but I wanted to report back on the progress.

If you find this issue with your car it may be helpful to note that the first replacement Air Guide Housing did not properly fit into the newly designed plate. I had to remove the new Air Guide Housing and return it. The second new Air Guide Housing was not much better. I ended up placing it into the plate and applying clamps for a week before reinstalling it. To avoid doing this job a third time, I applied a small amount of super glue around the forward rounded edge (see photo) of the new plate to insure it sealed properly until it was bolted down.

In closing I wanted to again thank the above referenced Moderator whom I now refer to as the Master! Your kindness, patience, and goodwill will never be forgotten! I also wanted to recognize the fantastic members of this forum that take the time and effort to help out people that they have never even met! I very actively belong to no less than 11 forums pertaining to Heavy Equipment, Fishing, Boating, Mercedes Benz, Snow Removal, Welding and IT. This forum is by far the most helpful! I’m proud to be a member and hope that someday I will be knowledgeable enough to Pay It Forward!

Tim
Attached Thumbnails
380SL Hard Start & Poor Mileage-img_0344.jpg   380SL Hard Start & Poor Mileage-crackedhousingaltered-copy.jpg   380SL Hard Start & Poor Mileage-pict1140.jpg  
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82 380SL 41K miles sold, 98 SL500 44K miles, 13 C300 4Matic, 14 CLA-250 4Matic
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