Because I want to help others with their cars, but don't have the knowledge-base of the amazing peachparts diesel crew to really answer any of these questions, I am taking an alternative track. I have decided to try to document my efforts to reinstate roadworthiness to a 1968 w115, 220D automatic that I inherited from my dad. The car sat in my mom's garage for about 8 years, and I am slowly getting it back into working order. My hope is that there may be other newbies out there who can learn from my successes and mistakes. I previously wrote about changing my vacuum pump diaphragm, and today I wanted to explain how changing the glow plugs went. These are the old, filament style gps (not the pencil type).

It is a pretty straightforward job, at first glance. You remove a few wires/connectors from the glowplugs, and then the glowplugs themselves. I had a 21 mm, 6 point, deep socket which was perfect for removing the first and the last GPs. Strangely enough, one of the GPs was in barely finger tight. It is amazing to me that it didn't fall out once I realized how loose it was. It had been that way for 17 years. For GP2 and 3, the injection pump or lines are in the way so my socket didn't work there. So I bought a $9 21 mm wrench today which took care of the other two. Other than the trip to the store, it probably only took 45 minutes to change them all and I am very slow at these sorts of things.

The old GPs were covered in a thin layer of soot, but I did not get the sense that carbon was encasing them in the engine. I did not ream out the bores, because I cannot afford the reamer tool. Maybe next time. The old GPs all looked identical. Two of the ceramic wire anchors were cracked, and I replaced all 4.

After installing the new Bosch GPs, my first impression is that it took a little longer for my salt shaker indicator to glow. This puzzles me, but it is only a first impression at this point. The car started right up, but was making the most horrific wheezing sound. I have never heard such a sad sound my engine. It was like it was gasping for air but on the injection pump side of the engine. So assuming I didn't install the GPs right, I felt near each GP for air movement. Not the smartest thing I have ever done, as the noise I was hearing was actually hot exhaust gases blowing out at one GP. So for some reason, I had a leak. It was the 4th GP and I know I tightened it fine, because it was one of the ones I used my large socket on.

Then I remembered a small pop or crack that occurred when I tightened that GP. It was insignificant at the time, but I realized then that I must have goofed up. So basically, after a bit of futzing around, I realized that I had somehow cracked the inner workings of the GP to allow it to leak. Basically, it still seats fine at the engine, but there is some internal path for exhaust through the GP itself. I verified this very scientifically by putting the filament end in my mouth and blowing air out the other end. Yum.

So my one bit of actual advice to others is don't overtighten your glow plugs.

So I ended up putting back one of my old GPs in until I can buy a new one. The car started up fine and all the wheezing is gone. This is a job that anyone can tackle and if I succeeded at it (mostly), you can to. Good luck.

I think you might find that a 13/16" Spark Plug Socket or Deep Socket will fit.

The Reamer for the Filiment type Glow Plugs is expensive.

I made a comment quite a while back that a Shot Gun Bore Brush might be able to be used. The Stainless Steel or Bronze ones I think would work.

I don't know what size would be needed and you need to come up with a Handle to attach the Brush to.

SHOTGUN BRUSH SIZES
10 gauge 0.775"
12 gauge 0.729"
16 gauge 0.662"
20 gauge 0.615"
28 gauge 0.550"
410 bore 0.410"

Note: Some people were worried about a Brush Bristle getting inside of the Engine.

Yet for 18 years I used Stainless Steel Brushes to clean out the Injector Tubes on other Diesel Engines and if you do a google search for Injector Brushes I bet you will see some.

Using such Brushes has never caused an issue that know of.

__________________
84 300D, 82 Volvo 244Gl Diesel

I recently used a brass brush from the hardware store to try to clean a metal fuel line, and had a slightly scary experience. It was the fuel line from the tank strainer to the tank exit. The fuel tank is under the trunk in my car, as opposed to behind the rear seat. I had black gunk growing on my tank strainer, so I wanted to make sure the line was clear as well. The selection of bottle brushes at my hardware store was very limited, so I bought a brass bottle brush that I think was intended for plumbers doing pipe fitting. Anyway, it turned out to be small enough to push relatively easily into the fuel line, but getting it back out was much more difficult. It simply wouldn't pull out. It took me a while to figure out that I had to "unscrew" it to remove it, which took a few minutes. All the bristles had folded over and were acting like fish hook barbs. Once I got it out, I flushed that line like crazy and no bristles had broken off. So this was a low quality brush that I totally abused and no bristles came off. But at the same time, it was a little disconcerting to have trouble removing it. So based on this experience, I decided to not ream the GP holes with a brush (shotgun or otherwise). If I can get my car working as a daily driver for a while, I may decide to invest in a reamer. But for now, it appears to be okay. Maybe not perfect, but okay.