restoring old diesel engine

My father has an old (~40 year) diesel engine he used on his CL plane when he was a child.

It is a David-Andersen Tellus 25 (norwegian model engine factory).

I am afraid it might get damaged if it is stored longer without doing anything with it. We started the engine about 8 years ago, and it worked then.

Now, the oil we used for storage, has gotten very hard and it is difficult to move the propeller.

What should I do? I want to do a full disassembly and clean it, but could use some advise. I know something about glow engines, but nothing about old diesel engines. But I guess they are just as easy to take apart?

How should the engine be stored after cleaning?

Asbjørn

Reply to
Asbjørn Djupdal
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Asbjørn,

I don't know any of the specifics about your engine, but I have restored quite a few antique U.S. engines.

The first thing to do is to find a solvent that will re-liquefy the oil you used for storage. You should do the cleaning and oil soak before you rotate the engine shaft very much.

If you remember the brand of the oil you used, you can check with the manufacturer to see what they recommend. The important thing is to use a solvent that will not attack aluminum or steel. If you have stores where consumers can purchase "do-it-yourself" auto repair supplies you might be able to find the solvent that is used to soak clean automotive fuel injectors and carburetors. Auto repair shops often have special ultrasonic tanks where they do this sort of cleaning and you might be able to talk one of them into cleaning your engine. The "green" regulations are a little tougher in Europe and the Nordic countries and that is why I am not making specific suggestions for a U.S. market solvent.

After the solvent soak, the entire engine in a high-grade, very light weight oil. If you can obtain the oil used for lubrication of air powered tools (air-tool oil), that is a good choice. In the U.S. there is a brand called "Marvel Mystery Oil" that I have used for decades. Soak the engine for a couple of days before you start to disassemble it.

Here is the voice of experience speaking: It is very important that the tips of any screw-drivers, hex wrenches, or regular wrenches you use for disassembly be a PERFECT fit to the fasteners. I have a complete set of SAE, Metric, and old British Standard tools with specially hardened tips and surfaces. I also have a special set of cross-point screw-drivers fabricated to have the correct fit with high quality Japanese fasteners. The last thing you want to do is damage the fastener with a poor quality tool. Due to the age of the engine, I would suggest that you take the engine with you to a good tool store so that you can trial fit a series of tools to get the best possible fit. I have found that tool dimension tolerances vary significantly across different manufacturers.

Diesel engines are some times designed to operate at higher internal pressures than our glow ignition 2 Strokes. The head and the head fasteners will probably be designed to handle more "clamping pressure" than you would see on a modern 2 cycle. When you remove the head fasteners, or any "pattern" of fasteners on the engine, loosen all of them equally and a little at a time. Most designers will have a specific torque pattern in mind, but loosening in an "X" pattern is generally safe. The trick is to allow the pressure between the parts to relieve in a balanced manner so that warping forces are kept at a minimum. The same thing apples to re-assembly.

If you have a digital camera that will focus on very small areas, I suggest that you take pictures as you do the disassembly. This is a good method of recording the orientation of parts. It is a good idea to make sure that even parts that will fit in one or more positions be reassembled in the same orientation to each other. Some engines have pistons and piston sleeves, rods, back plates, etc. that will "fit" in one of two positions. Some engines have piston sleeves that are manually orientated with the intake and exhaust ports and are held in the correct alignment by only the pressure of the head attachment. If there are no very visible indications that you can use to document the orientation, clean the part with a little solvent and mark it with permanent ink. Some guys use a very sharp and hard scribe to "scratch" a non-friction surface. I don't like making ANY scratches in stressed mechanical parts.

Are you planning on running the engine before putting it back into storage? I don't recommend running a "restored" engine unless you are prepared to do a full cleaning again and re-lubrication with storage oil. If you are not going to run the engine, you do not need to torque down on any of the fasteners. Just be sure to place a note on the Outside of the storgage container indicatng that the engine parts are not torqued "tight".

Storage: Any moisture in the storage air is a bad thing. It is not necessary to "pickle" an engine if you can protect it from all moisture. All you need to do is apply a >very thin< coating of the air-tool oil to the internal and external parts and seal the engine in a air-tight container. People who saturate engines with oil come up with the problem you have now.

The choice of the storage container is important. What ever you do, don't store the engine in a paper box or with paper in the same container as the engine. If you have the original box, store the box in a separate container. Be wary of inexpensive plastic storage containers - they can "out-gas" as they age and mess with aluminum and steel. If I am going to store the engine for only a year or so, I use double "zip-lock" storage bags. If I anticipate longer storage, I purchase the "Tupper-ware" brand of plastic container and I have never had any trouble with them. If you can obtain some desiccant crystals, place a small bag of them in the container witht he engine. These are the same things you see shipped as little packets with consumer electronic devices. I scrounge my supply from family, friends, and neighbors when they buy new TVs, cameras, stereos, etc. Don't use the stuff intended for removing moisture from large areas like closets and cupboards - it is a different chemical and produces a gas as it absorbs moisture.

I hope some of this has been of assistance.

Have FUN,

J

Reply to
Flightdeck

Hello,

Thank you very much for a long and informative article.

I have one question: The engine is normally placed in the old airplane. Since the engine is an important part of the plane, we would like to continue having it in the plane. Would covering the carb and cylinder be enough, or is it necessary to put it in a tupperware box to avoid damage?

You have been very helpful, and I am sure it will be of use for others in this newsgroup to.

Asbjørn

Reply to
Asbjørn Djupdal

Hi Brian

Thank you for your help.

I will check this. I would probably not have though about it if you didn't mention it.

pAsbjørn

Reply to
Asbjørn Djupdal

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