Tuesday, June 14, 2011

Checking the Valves W115 300D; Example of a Fuel Injection Line Problem

I am preparing to perform a leak down test on Marlene, but first I want to check the valves, to see if they are in need of adjustment. It has been over a year since they were last adjusted, but I haven't put that many miles on her in the interim. The odometer doesn't work, naturally, so I really have no idea. I do know that I drove it as a daily driver for a couple of months, but only sporadically after that. Certainly way less than 5,000 miles--- probably more like 2-3,000 at the most.

Here I am trying to insert the feeler gauge to check the #5 cylinder (nearest the radiator) intake valve. The .004 gauge won't fit because the valve is set too tight. Recommended practice when setting valves is to err on the side of 'too loose' rather than 'too tight'. This valve needs to be loosened.

This next intake valve is set properly, and you can see the feeler gauge is able to slip through to the other side, with just a 'slight drag' as it is pulled through. That is a technique that you will develop a 'feel' for, pun intended, as you do it a few times. When in doubt, I will test the gap with the .005 gauge, and if that gauge can slide through, it is too loose. I would tighten it a hair.

Here is another tight valve, as you can see. The .004 feeler gauge cannot fit, and is bending as I try to slip it through.

This valve is set OK, as were most of the rest. All of the 5 exhaust valves were set correctly, but I found three intake valves that were too tight.

Here is an example of a problem often talked about in diesel forums: the separator bracket is missing on the injection lines, and if you look carefully you can see where these two have been rubbing. There is also a little rust developing. That is trouble ahead. I will need to separate them better, and I probably should replace them to avoid a burst injector line. I HATE when that happens! :)

Tuesday, May 24, 2011

Thar She Blows: W115 Diesel Blowby Video

As part of the preparation for performing a leak down test, I reset three out-of-spec intake valves last Saturday. I was also curious about the amount of blowby that the engine was putting out.

Well, you may recall that Saturday was the day that some were predicting the world was coming to an end at 6pm. After finishing setting the valves about 4:30pm, I decided that I didn't want the world to end without recording for posterity how much blow-by Marlene was putting out. So here is a short video of the event. :)

How much blow-by is too much blow-by? Opinions welcome.

N.B. This diesel engine is consuming a quart of oil every 150-200 miles. Coincidence?


I really don't know how to evaluate the blow-by.... That is more of a sideshow.... I have heard from others that it is not that big of a deal...

My concern is the 1 quart every 150 miles, or so, of oil consumption. For the amount that I drive the car, frankly, even that isn't a big deal.... But I would like to determine the cause, and then decide what's to be done about it.

It is really a neat car, I like the style, and, as an OM617 W115, it is an historic and increasingly rare model.... So I would like to preserve it. Historic in the sense that the 1975 300D was the first time Mercedes put a 5 cylinder diesel in a sedan.... And it was only in the W115 for those two years, in 1975 and 1976. Then the W123 was introduced.

My son loves it, and I plan to give it to him at some point. I would like to give it to him in better shape than it is now.

Oh, and did I mention... It was also built the year I got married... So a bit of Romantic Nostalgia there also. It is more than just nuts and bolts, and dollars and cents.

All of the above enters into my decision as to what ultimately needs to be done to the car. More than you wanted to know, I am sure.

Monday, May 23, 2011

Mercedes Diesel Rebuilding DVD

I came across a website that offers a 4 hour DVD on rebuilding the Mercedes OM617 Turbo diesel engine for $79.98. It is a little pricey, and it is not technically for the W115 OM617, but it may be a valuable resource reference for someone to have. The engines are similar enough that I am sure that the DVD will contain much info that is relevant to the W115.

Check out the short example video.

Here is the main website:

I also added the above information to the "Service Manuals for the Mercedes W115 300D" post (May 13, 2011) in this blog.

Saturday, May 21, 2011

Making A Pair of Homemade Valve Wrenches

Adjusting the valves on a OM617 engine involves some tight angles to get your wrenches in. Mercedes recommends a special set of bent-handled wrenches to accomplish the task. You can purchase a pair of Hazlet wrenches... But they are pretty pricey.

Alternatively, you can bend your own wrenches to do the job. If you do a search (valve-wrench) in Peachparts Mercedes Diesel Discussion forum, you will find some pretty well done examples. Some guys buy a separate pair of 14mm wrenches, heat them with a torch, and bend them. Another alternative is to do what I did: go to your local bike shop, and buy a pair of their thin handled 14mm bike wrenches. I then put the wrench in a sturdy bench vise, put a piece of pipe over the handle for some leverage, and then bent it to the angle I wanted. They are not elegant, but they are simple to make. They work great, and they won't cost you a small fortune.

I had made a pair of these bike wrenches 10 years ago when I first got Marlene on the road, but, over the years, I seem to have misplaced one somehow. So I went out to the bike shop this week, and bought another 14 mm thin wrench for about 10 bucks.

Today I put it in the bench vise, slipped piece of pipe over it, and bent it. I have added some pics of the process. The first pic shows the bent and the unbent wrenches together.

The next pic shows the wrench in my bench vise.

I now have placed a piece of pipe over the handle of the wrench to get some leverage to bend it to the angle I need.

This pic shows the two wrenches again ..... Both bent now.
You can tinker with it a little more to get the angle just right. The only drawback to using thin handled wrenches like these is that you may feel a slight bit of flexing as you tighten down the valves. These worked fine for me today, but I did recheck them with a regular wrench to make sure the lock nut was tight.

I have added a link to the Diesel Giant Valve Adjustment Procedure in the sidebar. Please check it out if you are thinking that it is time to adjust your valves.

Saturday, May 14, 2011

Old Faithful Starts Marlene May 14 2011

Old Faithful

I inherited "Old Faithful", a circa 1960's battery charger, about 18 years ago when my Dad passed away.  It had served him faithfully at his Sunoco Service Station since at least the early 1960's, and probably before that.  I can remember using it to charge batteries and start cars when I worked there in high school and college. I have used it to start 'Marlene' on countless freezing New England winter mornings over the past 11 years. Although it is now nearly 50 years old, it has never failed me.  It creaks and groans a bit as it starts up these days but....  then again, so do I.  We have that in common, and perhaps that explains why we have gotten along so well all these years.  ;)
In this picture I am using Old Faithful to jump start Marlene today to move her into the garage to officially begin the restoration project. Drumroll please. :)

Here you can see that Marlene is safely ensconced in the garage, although.....

it is a tight fit!!

Work done for the day, I prepare to curl up with a good book (Chilton's Mercedes Service Manual) in a comfy chair, complete with my car ramp ottoman, and a nice glass of Cabernet Sauvignon in the newly-created lounge area of The Backseat Driver's Baur and Grill Club (my garage).   More on that in a later post.

Friday, May 13, 2011

Service Manuals for the Mercedes W115 300D

UPDATE II: I came across a website that offers a 4 hour DVD on rebuilding the Mercedes OM617 Turbo diesel engine for $79.98. It is a little pricey, and it is not technically for the W115, but it may be a valuable resource reference for someone to have.the engines are similar enough that I am sure that the DVD will contain much info that is relevant to the W115.

Check out the short example video.

Here is the main website:

UPDATE:  I am taking Peachpart forum member Army's suggestion to include some other online resources, such as mailing lists and forums that can be a resource for W115 owners.  Thanks, Army!
Peachparts Diesel Discussion  Forum:

New Mercedes forum catering to the W114/115 Series:

Kaleb Striplin's Mercedes email List:

Any other suggestions are welcome.

This is a partial listing of some of the service manuals that are available for the Mercedes W115 300D. I have copies of all of the manuals listed below. There may be other manuals available. In addition, Mercedes did offer the official Factory Service Manual, I believe. I do not know whether it is still available through Mercedes, but you can probably find one on EBay or Craig's List from time to time. I believe that the FSM is available on CD, and that is what I bought on eBay a few years ago. Or at least I THINK it is the FSM that I bought.


There is no Haynes Manual for the W115 that I am aware of. The Haynes W123 Manual has info on the early W123 300D engines, which are similar to the W115 300D engines. There are some differences, however, so proceed carefully.

Anyway, here is the partial list of Mercedes Service Manuals that may be helpful to the W115 owners out there:

Mercedes-Benz Tune-Up Maintenance
Gas and Diesel 1958-1976. Clymer Publications. 1976.

Chilton's Repair and Tune-Up Guide Mercedes-Benz 1974-84
Chilton Book Company. 1984. Part No. 6809

Haynes Automotive Repair Manual
Mercedes-Benz Diesel 123 Series 1976 thru 1985
4 & 5 cyl. Haynes 63012. Haynes North America, Inc. 1986.

Chilton Mercedes Coupes/Sedans/Wagons
1974-84 Repair Manual 48300. Chilton Automotive Books. Published by Haynes North America, Inc. 1997. Includes Wiring and Vacuum Diagrams. Or so it says. I don't see any wiring or vacuum diagrams here for the W115 300D. Those are very hard to come by, in my experience. If anyone has info on that, please email me and I will be happy to post it here.

I have a pic posted of the cover of this manual, if anyone is interested. It is in the post on May 10, 2011 entitled "Getting "The Backseat Driver's Baur and Grill Club' Prepped for Marlene's Restoration".

I will try to get some pics of the covers of the other manuals I have listed here, so you can see what they look like.

Mercedes-Benz Model 114/115 Service Manual Library
Compact Disk
Complete Service Manual. I purchased on EBay from a Vendor in Turkey a few years ago.

5/14/2011 Update: Thanks to forum member Diesel911 in PeachParts Mercedes diesel discussion forum for posting this link as a source of DVD and CD Manuals.


Here is a link to the thread in PeachParts Diesel Discussion, another valuable resource, btw:


Thank you, Diesel911!

This link was posted by PeachParts forum member Army. Although it is for the W116, there may be some useful cross-references for W115 owners.


Thank you, Army!

I always like this sort of info on all the W114/115 Series:


New Additions to the Sidebar

I have added a couple of links to the sidebar related to W115 restorations. Both just happen to be white W115s, at least at the beginning. One is a YouTube video, and those are always fun! Please check them out. :)