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Today some friends and I (all mechanics) were talking about the nicest tools to have as diesel mechanics. The ones that make life so much easier if you have them but make you want to consider a career change if you don’t. I just want to give you a breakdown of the tools we discussed and why they are so valuable. First and foremost, is the basic multimeter. If you plan on working on any vehicle, your or not, you really want to have one of these. Today’s automobiles have computers with sensors, switches and relays. If one of those goes wrong it can throw off the entire engine. I mean everything. A good multimeter will include modes for checking A/C, D/C, continuity, ohms and amps. Often times a problem will be electrical rather than mechanical. If you don’t have one of these you can forget it.
Next is a baring socket. Most people probably have never heard of this thing. If you need to find top dead center (TDC), you can try bumping the engine but that task is almost impossible in a diesel. TDC is used to time certain fuel pumps, well almost all heavy equipment fuel pumps. A baring socket slides in to interlock with the flywheel to slowly turn the crankshaft so the desired piston will be at top of it’s reach. There by allowing you to time that particular injector. It is also a pretty easy way to determine the stroke of a piston.
Compression testers are an invaluable tool to have if you are working on a diesel, especially one that is lacking horsepower. Since diesel engines rely on compression to achieve combustion, if you start to lose compression you will before long lose combustion. In addition to lacking in horsepower, fuel mileage will be lost too due to the wasted fuel that is getting injected into the cylinder and not being burned. Also, a serious compression issue will result in hard starting and the untimely death of a starter. A compression tester will also help you to determine if you have a glow plug problem or a compression issue to avoid the guess work of diagnosing a starting problem.
A double flaring tool kit is also nice to have. To be honest, this is not something you really miss until you need it and don’t have it. Flaring kits provide ease in re-flaring a fuel line, brake lines or other steel or copper lines that may kink or get broken. I’m not aware of any other way or tool to achieve a double flare. Some people will opt for a single flare, thereby decreasing the strength of the flare by at least half, resulting in future problems. Last on the list of most popular tools is a set of line wrenches. They look like box end wrenches but with a notch cut out of them. Anyone who had ever had to loosen a fuel line on a diesel will swear by these things. They allow you to lift up the wrench to turn it to get a better bite without actually having to take the wrench off the line. If you’ve ever done this with an open end wrench you’ll understand. They work just as well for any other purpose that a regular wrench would be used for too but with the added benefit of expanding your options. Every diesel mechanic should have a set of these in their box. You won’t be sorry.

In the time I’ve spent as a mechanic, (primarily a diesel mechanic) I learned a few unconventional tricks and a lot of lessons. I usually find myself dealing with problems such as broken or “mushroomed” glow plugs. This issue comes when carbon continues for long periods of time to cake on the glow plug since diesels are famous for smoking and being not-so environmentally friendly. The glow plugs are not actually mushroomed but they do fit (when new) into a nice tight hole so when they start to accumulate carbon buildup, they get thicker at the end, we call that being mushroomed. The next thing that usually involuntarily takes place during the removal process is breakage. You don’t really have a lot of options when you get to this. When breakage does occur, you have two options, neither is very favorable.

Option one, since you now have a piece of glow plug broken off inside the cylinder, and that can’t stay there, you can remove the head. Heads are famous for being heavy, placed at angles as to not be user friendly, they usually have other parts of the engine that need to be removed just to get to them and they are very, very picky about how they are reinstalled. You have specific torque specs and you have to tighten the bolts in a certain order. We will discuss this topic in a later issue.
Option two, you can drain the oil from the pan (which is usually very easy), disconnect the oil pan from the block, disconnect the piston that is housing the broken glow plug from the crankshaft since there are only two bolts and they are very easy to get to also, then just pull the piston straight down out of the cylinder. Once you get the piston out, the glow plug piece will fall right out.
Now that you have the culprit it’s time to put this thing back together. I know a lot of people who think the worst job in the world of engines is to reinstall a piston. This however, is an easy task if you have the right tools. The particular tool that I love is a piston ring compressor. It’s cheap, easy to use and there not hard to find. In addition to the ring compressor you really don’t need any other tools besides a good socket set with extensions. It’s good to have standard and metric since some manufacturers chose to use both. Also, a rubber or wooden mallet is almost a must have.
So, you have the piston out and the glow plug piece is removed. Now you have to reinstall it. Just loosen the tightening bolt on the side of the ring compressor and slide it over the piston, making sure that your oil rings are offset properly to reduce blow by. Once that is on, tighten the ring compressor until it’s good and snug and the rings are compressed fully. Be sure to keep about a half inch of piston above the ring compressor to assist in guiding the piston home. Install the piston into the bottom of the cylinder until the ring compressor is seated against. the block. With the mallet, lightly tap on the bottom of the piston assembly or piston wrist. The piston will slide right into the cylinder as long as you are sure to keep the ring compressor against the block. Once you feel the piston slide into the cylinder and the rings are seated inside the cylinder the compressor will slide right down. Now just slide the piston up and/or down to realign it with the crankshaft and replace the lower portion of the piston wrist around the crankshaft. Make sure you tighten the bolts to mfg specs. Replace your oil pan and refill with oil. Now you have successfully fixed the problem.

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