Start Your Engines!

Part three of three on restoring a 4 HP Charter-Mietz oil engine


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I knew how a hot bulb engine worked, so I figured it wouldn't be too hard to start it on my own. The more I thought about it though, I figured I would read the section in Dusty Erickson's book (Mietz & Weiss, New York, America's First Successful Oil Engine) to be sure I got it right the first time.

A hot bulb or oil engine is not the same as a hot tube engine. Although a hot bulb engine also uses heat to light the charge, it is a totally different system. On a hot bulb engine, the engine head has a bulb or protrusion on the head of the engine that is heated red hot with a torch. On the intake stroke, only air is drawn into the engine cylinder. At the proper time, during the compression stroke, fuel is introduced into the bulb via the fuel injector where it vaporizes, mixes with the air in the combustion chamber and flashes into flame, providing thrust against the piston.

Like a diesel engine, the timing and the duration of the injection of fuel determine the power and speed of the engine. Oil engines are sometimes called semi-diesels. The major difference between the true diesel and the hot bulb engine is the compression ratio. A true diesel engine operates by compressing the air in the cylinder at fantastic pressures. This pressure generates heat, which in turn ignites the fuel as it is injected into the combustion chamber. Some of the lower compression diesel engines need a glow plug to provide enough heat for starting in cold conditions, but once started, the glow plug cools off and the engine runs on compression alone. Diesels run most efficiently between 18-to-1 and 22-to-1 compression ratio. The typical oil engine is nowhere close to that. My Charter-Mietz, for instance, has a compression ration of only 5.5-to-1. Once a hot bulb engine starts, the preheating flame can be removed as the heat supplied by engine combustion provides enough heat to maintain ignition.

I was told that the small Bunsen burner I was given was used to start the engine, so I hooked it up to a new 14 ounce propane bottle and prepared to heat the hot bulb. I had read in Dusty's book that you had to open the shutter in front of the hot bulb chamber in order to allow the flame to travel around the bulb. I tried to open the door in front of the head by gently tapping on it, but it was frozen fast. I then used a large pair of channel lock water pump pliers and the door finally moved. It took the mounting bolt with it! I put the bolt in my vice, poured a lot of Liquid Wrench on it, heated it bright red and then allowed it to cool until it was no longer red. The bolt then came loose easily.

Next, I decided to inspect the heating chamber to see if there were any unwanted guests. I found some! There were two mud dauber nests, a yellow jacket's nest (with bees to boot) and a lot of spiders. A load of Berkbile 2+2 carburetor cleaner and the air compressor took care of the critters.

I reinstalled the cleaned door assembly onto the hot bulb chamber and then opened the door. I lit the Bunsen burner and let it burn under the hot bulb for about 10 minutes. I then tried to roll the engine over to start it, but I could not get it to go over the compression stroke. I opened the compression release and tried again. This time the engine rolled over, but still gave no hint of trying to start. I let the burner burn another five minutes until it almost went out and tried again. Still no luck. I had totally used up the bottle of propane. I decided that more heat was needed.

I got out my plumber's acetylene torch and lit the hot bulb. After a few minutes I noticed a lot of white vapor coming out of the compression release port. I tried rolling the engine over and got great plumes of vapor out the compression release and the exhaust port, but no hint of ignition. I closed the compression release and tried pulling the engine over with no success. Then I remembered a trick I had pulled when I was a kid. I was trying to remove a stuck piston from a 2 HP Witte headless engine and had loaded the cylinder with kerosene and heated it. As vapor was escaping from a removed plug in the head, I decided to pass a lit torch over the vapor plume. The resulting explosion blew the piston and connecting rod clean off the engine and through the garage door! That was a hard one to explain to Dad. I decided to try this maneuver now.

As the piston and rod were attached to the engine this time, there was a different result. I rolled the engine over a few more times and held the lit torch near the compression release port. The thick white vapor lit with a WOOSH and the flywheels turned a little bit under their own power. But as soon as the exhaust port was uncovered, all hell broke loose. The stored up vapor in the 2-inch exhaust pipe lit with a loud bang of an after-fire explosion. Orange flames shot out of the exhaust pipe and the compression release. I could smell that a couple of spiders did not survive that experience very well.

I put the torch back under the hot bulb for a few more minutes, and when I again saw the white vapor, I closed it. I pulled the engine up against the compression stroke with the flywheels turning toward the head of the engine, over the top. I had only gotten a little compression when the flywheels were pulled out of my hands. The crankshaft rolled clockwise against compression and the engine fired with a dull thud. The flywheels reversed direction, hit compression, fired and reversed again! This firing and crank rotation reversal went on for about 15 rockings before the flywheels finally got enough inertia to carry over the compression stroke. After that, the rest is history.

The engine began to belch a heavy mixture of white and gray smoke, so thick that I could not see past 10 feet. I decided the engine was flooding so I held the fuel pump drive primer lever forward, stopping the pump. The engine did not stop though. It continued to accelerate even faster, so I opened the compression release to slow the engine. It continued to fire for several minutes, even though the compression release was wide open, before it finally quit. The compression release was so hot I could not touch it or turn its handle with an adjustable wrench. The Charter-Mietz actually ran though, for the first time in over 25 years!

My second attempt at starting went better. I pulled the primer lever twice, heated the head with the plumber's torch and after five minutes or so, rocked the engine. This time, when I saw the white vapor, I closed the release and rocked the engine hard against the compression stroke in the opposite direction I wanted the engine to turn. It fired, carrying over the compression stroke the first time and the engine sped up to governed speed and stayed there. What sweet music to my ears! As the engine ran, I noted that the exhaust note seemed muffled and kerosene was leaking from the injector piping at both ends at the solder joints. I shut off the fuel valve and let the engine coast to a stop.

The next afternoon, I took the injector supply pipe off and cleaned it with electrical contact cleaner. I blew the pipe out with air and heated the brass fittings in order to remove them, as I also had to clean and re-solder them. The repair of the one at the pump end went well, but the one at the injector end was another story. The brass fitting had split up the side and as the area was still dirty, solder would not take. I had some Muriatic acid left from a cleaning job, so I placed a small amount in a plastic container and put the brass adapter in the cup, slowly. After several minutes, I removed the adapter and put it into another container that had baking soda and water in it to neutralize the acid. I dried off the fitting, blew it off with air, re-cleaned the piping bore with the drill and emery, and again soldered the fitting onto the tubing. This time the solder took and sealed the crack as well.

I took the remaining acid and poured it slowly into the other container (the one with the baking soda) in order to neutralize all the acid waste. (Never pour anything into acid because it can generate tremendous heat and can cause an explosion. Always pour an acid into the neutralizing solution. It will remain cool and will not harm you if it is spilled.) With the repairs to the fuel injector piping finished, I polished the brass fittings, and installed the piping assembly and tested it by using the priming lever on the primary pump. No leaks!

The cooling system

In speaking to Dusty and Fred, they both told me the Mietz &Weiss engines liked to run very hot. A lot of owners do not even put water in the engines! I did not feel comfortable running a kerosene-burning engine for a long time with no cooling - especially a hot bulb type. The heat build up would be tremendous! As the engines like to run hot, I decided to make the cooling system as minimal as practical, yet allow the engine to run for several hours without a lot of maintenance. I decided to make a water reservoir out of a piece of 4-inch K copper pipe I had in the garage. I measured the distance between the 3/4-inch pipe nipples already on the engine and added 8 inches to the measurement. I cut the pipe to length, which turned out to be about 2 feet long and soldered a sweat cap to what would be the bottom of the water reservoir. This done, I held the reservoir next to the nipples mounted on the engine and scribed marks onto the side of the container, double checking the locations. Once I was sure the locations were correct, I used my drill and a Vari-bit to open the holes to about 3/4-inch in diameter.

I used a 3/4-inch pipe tap to make threads into the side of the container. I installed two brass nipples into the wall of the copper vessel and then put brass unions onto them. The unions were used in order to make any necessary adjustments in the length of the piping and to make it easier to remove the reservoir in case the engine had to have the water drained. I also replaced the broken thermometer with a 260-degree thermometer I purchased from my local hardware store.

Thankfully, I got the alignment of the 3/4-inch piping on the reservoir right on the first try. Since this engine operates on a thermosyphon cooling operation, I filled the reservoir with water so that it was about 3 inches over the upper piping. I started the engine, and after about 30 minutes the water temperature was only about 200 F and the water level had hardly dropped.

Exhaust pipe

I decided at this time to make an exhaust pipe for the engine, as the original open pipe was pretty loud. I put a 2-inch diameter, 90-degree elbow on the exhaust pipe nipple that was originally on the exhaust tee and turned the open end up. I soldered a male fitting, by sweat adapter, onto a 4-foot piece of 2-inch copper tubing and installed it onto the upturned "L." After another test run, I now figured the engine was ready to take to a show.

I had learned from Fred Pritchard that the Mietz & Wiess, as well as the Charter-Mietz engines, originally used a Hauck kerosene torch as the heat source for the hot bulb. This torch was made especially for starting these engines, as the actual torch head operated in an upright position.

I located a Hauck Model 10 starting torch on eBay. However, for now I will continue to use the acetylene torch, as using the original requires up to 15 minutes to generate enough heat to start the engine! My acetylene setup only takes four minutes - tops.

The show

The Denville, N.J., Historical Society has an annual show at the historic Ayers/Knuth Farm. The North Jersey Antique Engine and Machinery Club runs a display there every year, and we demonstrate engines and tractors at work. I decided this was the perfect setting for the engine's first public display, so off we went! I ran the engine for eight hours that day and discovered some problems.

First was the water reservoir. After eight hours of running, I noticed that the water was steaming more than it was earlier in the day. A quick check on the water level had me scrambling for a paper cup and a lot of water! The water level had fallen to about halfway down the side of the cylinder. I soon had the water over the upper pipe again, but two hours later, it was another scramble to get water. I needed something to tell me the water level.

Second was the upturned exhaust. Although the engine made some beautiful smoke rings when she started, she also had the nasty habit of chucking quite a few drops of nasty, black, used 50-weight motor oil into the air along with them. The ground for about 20 feet around the engine was covered with 1/4-inch black dots. Then again, so was anybody who stood near the engine for any length of time.

Third and most important, the fuel pump was losing kerosene at a prodigious rate. I soaked an entire roll of paper towel during the course of the day due to a leak at the primary fuel pump shaft packing. I tightened the packing gland many times, sometimes tight enough to jamb the pump, only to have it start leaking again five minutes later. The eight-hour show took 2-1/2 gallons of fuel!

Fourth was the fact that the cast iron fuel tank lid practically vibrated itself off the tank due to the fact that the engine is not well balanced internally. The Charter-Mietz engine is meant to be permanently mounted on a concrete pad. The sheer weight of the engine precludes that it will not move much on the cart, but move it does.


I decided to add a boiler sight glass to the water reservoir so I could see the engine water level without having to peer into the top of the reservoir itself. I purchased an old NOS unit with a 12-inch sight glass. I scribed two marks on the reservoir where I wanted to mount the boiler gauge and removed the reservoir from the engine. I drilled the 1/4-inch pilot holes and re-drilled the holes this time making the pipe holes 1/2-inch to fit the gauge mounts. I tapped the holes 1/2-inch NPT and then installed the gauge mounts and the glass. Finally, the two copper glass protectors were dropped in place.

The exhaust work got a little more extensive then I bargained for. When I removed the 4-foot pipe and the elbow, I found the tee on the exhaust manifold was loose. I decided to tighten it, as I had the tools out already. I took the exhaust manifold clean off the engine and stuck it in my big vice. At this time, I was interested in seeing what the heat exchanger actually looked like, so I tried to remove it from the tee while it was in the vice. I could not budge the heat exchanger with a 2-foot pipe wrench! I ended up using a 3-foot pipe wrench with a 3-foot piece of 2-inch copper as a cheater bar on the wrench handle to finally break the fitting loose - loose, but not out. I had to use the 2-footer to turn the exchanger fitting out of the tee. At last it was free, but the exchanger would not come out of the pipe threaded opening. After about two hours of turning, twisting and banging the poor exchanger, it finally fell out of the tee.

It was a mess! At first I could not tell what the exchanger was made of or how it was constructed. The heat exchanger is made of 3/8-inch OD copper in a tightly wound double coil that was approximately 2-1/2 inches in outside diameter by 3-1/2 inches long. If it were to be stretched out, there would be about 3 feet of 3/8-inch tubing. It was so badly caked with carbon that I was surprised the engine ran with it in place. I also cleaned out the tee, tightened it in the manifold and cleaned the exchanger itself. I used a piece of oak scrap, a brass wire brush and a couple of screw drivers as well as two cans of 2+2 carburetor cleaner to clean the caked material. I reinstalled the tee and the manifold, and changed the route of the exhaust piping. Instead of turning up, I removed the 2-inch screw elbow and the mounting nipple, and screwed the 2-inch male adapter and attached pipe into the exhaust tee. I cut off the excess pipe with my trusty Porta-Band saw and attached a 2-inch sweat, 90-degree elbow looking down toward the ground with a self-tapping screw. As the exhaust pipe now sticks outside the side of the cart, I wanted the outside part to be removable, in case I had to get the cart into a tight place.

I did some research on the engine fuel routing. In looking at the ratchet wheel pump drive, I concluded this engine was set up for multiple fuel usage. The poorer quality fuels were run through the heat exchanger and through the secondary pump mechanism, then to a second injector on the engine cylinder next to the primary injector. Fuel mixture on the secondary pump is made with a set bolt and locking nut mounted within the guide block pushrod mounted before the pump. The primary pump guide and pushrod do not have this feature and I believe the primary pump's adjustment is actually made with the governor. The primary guide does have a priming handle though the secondary does not. I made up a set of fuel lines for the heat exchanger and installed them. One line is connected to the engine mount next to the manifold as a way to anchor the exchanger in position. The other end goes to the secondary fuel pump inlet check valve. As the secondary injector is not mounted in the engine, the connection was mocked up for appearance sake by soldering part of a 1/4-inch compression fitting onto the brass plug in the injector mount hole and piping to the secondary pump discharge.

Then I tackled the primary fuel pump leakage. I had to remove the primary fuel injector piping as well as the fuel line from the kerosene tank before I could remove the pump body from the transfer cover-pump mount. I took apart the pump again in order to see why the fuel was leaking past the packing gland nut. Upon close inspection, I found the fuel pump piston had a rough surface due to the rust that formed when the pump had water in it. I had cleaned it earlier with some emery paper, but I guess the pitting was too deep. I tried again to clean the shaft, but did not bother to install it, as a lot of pits could still be felt. I decided a new pump piston needed to be built. I ended up buying two bolts, a 5-1/2-inch and a 6-inch. I cut the threads off the two bolts and tried them for fit in the pump housing. I ended up using the 6-inch after profiling the end that was in the pump, to match the original. I also polished the bolt shaft and assembled the pump, installing new packing while I was at it.

The last repair was made to the fuel tank lid. As the lid sits directly on the tank, I had to devise a way to make the lid stay put. I ended up putting a solid rubber bungee cord onto the tank, wrapping it around the lid-lifting knob. This effectively made the lid quiet, but I'll have to find a more sightly remedy in the future.

Back at the show

The next show I attended was the Hudson Valley Old Time Power Assn. show in Hudson, N.Y. As I drove onto the show grounds, I gathered a good sized crowd of people. Many started asking if I was going to start it and I answered, "As soon as I?get it out."

I had plenty of help getting the monster off the trailer. I filled the kerosene tank 3/4-full of fuel, opened the gas to my acetylene torch, lit it and began heating the bulb. After answering all kinds of questions about the engine, I opened the compression release valve, turned on the fuel valve and pulled the primer handle on the primary pump a few times. I then gently pulled on the flywheel. A lot of white vapor came out of the compression release port so I closed it. I turned off the torch and rocked the engine crankshaft flywheel against compression. The people stood mesmerized by the engine's flywheel rocking antics! It must have reversed eight times before it got up enough inertia to carry it over the compression stroke. When it finally carried over, it ran up to full speed and then quit.

As it was spinning down, I noticed the pump plunger was not moving. It took a second to realize the plunger was stuck. I tapped the plunger with my finger and it started pumping again. By this time, the flywheels had lost enough speed that the engine was going to stop altogether. I gave the primer a double pump and the engine fired, reversed and kept on running. You should have seen the people jump! It was quite a show for the first 15 minutes. The engine ran all day, hardly missing a beat.

As it was running at about 210 degrees Fahrenheit, I had people asking if it was a steam engine! I must have given the hot bulb's operation speech a dozen times that day. The Charter-Mietz used a little more than a gallon of kerosene in eight hours of running. One of my twin sons, John, had come with me and during some spare time he began polishing some piping on the engine. He told me the fuel pumps were made of brass, too. I took a look and lo and behold, he was almost right. Both fuel pumps were made of bronze. The rust I saw on the surface of the paint must have come from something resting on the engine some time in the past and it rust-stained the paint. Now I had another project.

While I was cleaning all the brass and bronze, I was looking over the engine's general appearance. I decided to leave the paint as found, as it was about 95 percent there. While I was looking, I again noticed the 3/8-inch pipe-threaded hole above the rear air intake on the engine subbase. This hole actually generated more vacuum than the engine induction on the intake stroke. I remembered a hole on the transfer port, near the piston oil inlet, but further toward the top of the port. I did not see where it went. I opened the compression release and blew into the pipe connection with air and it came out the combustion chamber.

As there was only one item this engine was missing, compared to the regular Mietz & Weiss engines, that being the water-steam induction, I decided to install one on my engine. I connected a 3/8-inch specialty tee to the female connection on the block of the engine and installed a 3/8-inch flare male adapter on the tee. I left one end of the tee open so if water should condense in the piping, it would have a place to escape instead of being trapped in the line. I routed the 3/8-inch OD tubing to the top of the water reservoir, and drilled and tapped a 1/4-inch pipe thread into the side of it. I threaded an old bronze gas cock into the reservoir. I flared the 3/8-inch tubing and attached it to the valve and the tee in the block. The steam induction piping works fine!


Recently, I took the engine to the Coolspring show in Pennsylvania, and started the engine many times to the amusement and entertainment of quite a few people. One of those people in attendance was Dusty, the gentleman who wrote the book about Metz &Weiss engines!

I was setting up my display and I noticed a man looking at the engine with great interest. I asked him if he wanted to see it run, and his face lit up with a big smile as he asked, "Could you?" I lit the acetylene torch, opened the fuel and compression release, and gave the Madison-Kipp a few turns. I continued setting up my display, which included a copy of the July 2006 Gas Engine?Magazine, with the first part of this artival in it, as well as the Hauck no. 10 ignition torch. Three minutes later, I pulled the primer handle on the primary injector pump a few times. The engine responded with a loud bang out the exhaust port that made both of us jump!

I closed the compression release, rocked the engine on compression, and again hit the priming lever. The engine lit right off and ran as pretty as a picture. The gentleman just stood there, watching the engine intently. After several minutes, I demonstrated all the injector pumping options, and turned the fuel selector off. As the engine rolled to a stop, it rocked between compression strokes. I re-opened the fuel valve and the engine rocked, firing, and then started in the opposite direction, belching out a huge cloud of blue-white smoke.

After another two-minute run, I shut the engine down, as I had not yet put water in the reservoir. The man walked up to me, held out his hand, and said, "The photos you sent me do not do the engine justice, I'm Dusty Erickson. It is one thing to see pictures; to see this engine in person, well, this is an experience," he said. "I have never seen another like it; it is so the same, yet so different. This is fantastic!" He thanked me for running the engine for him, and asked me several other questions about its operation and how it runs.

For instance, it likes to run reversed better than forward and it uses about one quart of fuel in 10 hours. Unloaded it weighs 1,500 pounds without the cart and uses about a cup of water an hour, as steam is taken into the engine to prevent knock. We exchanged some more information and he took a few photos of the engine. Dusty shook my hand, said thanks again, and went on to see the rest of the show.

Final adjustments

I have mounted a no. 6 turbo tip acetylene torch to the engine hot bulb assembly. This will allow me to provide the heat for the hot bulb exactly where it is needed, consistently. It used to be a guessing game as to how long and where to heat the bulb for quick starts. With the turbo tip, I get good heating results and starting availability in less than four minutes. I also painted the hot bulb housing with Krylon Hi Heat semi-flat black paint to prevent rust.

In general, here are the unusual characteristics about my Charter-Mietz engine: While normal flywheels are two, 42-inch wheels, weighing 225 pounds each, mine are twin 24-inch wheels weighing 325 pounds each. Second, there is no steam dome or water feed assembly on the outside of the engine cylinder, nor are there provisions for one. Third, the Madison-Kipp oiler; although Dusty has advertisements about the Charter-Mietz and M&W engines having these oilers, this was the first time he had seen one mounted. The same went for Fred Pritchard. Fourth were the dual fuel pumps and the ratcheting assembly. The left hand primary pump is definitely M&W design; however, the timing ratchets, camshaft and the secondary pump have never been seen or mentioned before. Fifth, the heat exchanger is unique to this engine; no one has seen the like on this puppy either. Sixth, the engine serial no. is at least 1,000 higher than the next known engine. (As a side note, Dusty is compiling a worldwide registry of all the M&W and Charter-Mietz engines, of which mine seems to be unique out of more than 70 M&Ws in over 13 countries so far.) Seventh, the two-position fuel valve, not known on any other Charter-Mietz engine. Eighth, the steam inlet passage location is different from the standard as well. Ninth, the engine weight is extremely heavy for its size. Tenth, the main bearing supports have four external buttressed supports. This also is not a regular Charter-Mietz feature and probably was done to support the extra-heavy flywheels.

I would like to extend a special thanks to Bill Popalell, the previous engine owner, without whose trust and faith in my ability and honor, none of this would have been possible. And to my wife Mary, who has been so patient through the years, my special thanks and my love. Thanks also to my twin sons Richard and John for their help.

Contact Andrew?Mackey at 26 Mott Place,?Rockaway Boro, NJ 07866-3022;