The M and ML engines were the largest stationary engines made by McDonalds, starting with the M in 1936 rated at 45/50 BHP, then upgraded with loop scavenge in 1948 to become the ML, rated at 65/70 BHP. They have a bore of 11 1/2" and stroke of 12" (about 20.4 litres). A total of about 326 engines were made up until 1961. Incidentally, the horsepower rating is 65 BHP continuous, 70 BHP short duration peak power.
These engines were widely used in the sawmilling industry, and also driving irrigation pumps. Their torque was legendary, being able to hang on to a load beyond all expectations. It weighs in at 3 tonnes without clutch or exhaust etc.
My engine actually saw service at a truck-stop service station on the old Hume Highway just north of Yass, NSW, where it produced all the power required for the site, using sump oil as fuel. I had become aware of its existence through contacts, but did not think it feasible to do anything about it being so large. About 1989, the opportunity arose when a friend acquired a 4-cylinder Southern Cross engine from the same location, and he offered transport. My offer of $100 was accepted by the service station, and my first trip was to retrieve as many accessory items as possible such as clutch, pedestal bearing and mount, lubricator, and the exhaust system. This much was indeed a trailer load! The head was missing from the engine.
In due course the engine reached home after two crane hires, and I set about finding a head, as well as mounting the beast somehow. Now that exhaust is quite an item. The manifold exits from the front of the engine to a 10" diameter horizontal pipe that enters the base of a 4' cast iron sphere which is the muffler, and then exits vertically via a 12" diameter pipe. The sphere is in fact a WW2 sea mine casing, which McDonalds adapted for the purpose. I had a contact in the Riverina District who actually owned one of these engines set up and running, and he offered to fabricate a substantial steel base and deliver it. When it arrived, a crane was engaged to place the engine on the base. This included a mount for the pedestal bearing as well as the exhaust. Through an advertisement in TOMM, contact was made with the owner of several McDonald engines near Tamworth which were duly acquired and transport arranged home. This included an M, and an ML complete with head. The head was transferred to my original engine and everything set up for a run. Heat was applied (I recall using an oxy torch - naughty! naughty!) and she fired first attempt. But didn't it shake! The engine, when gaining or losing speed, shook with such force it threatened to walk away. The latent power under acceleration is something to experience!
So, I was not game to run it again, and ultimately some components were robbed to further other projects. When the opportunity arose, a hole was excavated under the base and a quantity of concrete poured in to anchor it. Another job that was done was to remove the fixed pedestal bearing mount and replace it with the original hand-wheel operated clutch mechanism.
Fast forward to late 2014, and with the completion of a couple of other projects, I was inspired to get it running again. Quite a bit of work was necessary: truing up the pedestal bearing to eliminate possible flexing of the crankshaft; cleaning out the rats nest inside the engine; draining the 2" of water from the lubricator; and most importantly, making up a workable fuel pump and atomizer. The clutch is seized due to weather damage, but this is unimportant. With a fuel tank stand being fabricated, it is just about ready for a start - that is until I checked the integrity of the horizontal section of exhaust pipe only to find it rusted away at the bottom. After quite a struggle it has been removed and the search is on for some 10" diameter pipe. The original was rolled and seam welded, and that may be the only solution.
The problem has been solved by acquiring some quite heavy 220mm diameter pipe which enabled the original flanges to fit with just enough room for the bolts. In the process the muffler has been removed and cleaned out, and the I-beams around it cleaned up and rust treated, and all reassembled. The fuel tank stand has been set up and piping attached to an old fuel tank. The injector line fittings would not seal, so completely new fittings have been made and hard soldered to new pipe. Fuel has been added and apart from a leak from a cock under the tank itself, it primed with little difficulty. However, the atomizer (Injector) produces a reasonable spray pattern with a good shot of fuel, but tends to dribble with a small pump movement. Will it be good enough? Atomizer nozzles are like hens teeth.
After a couple of heating sessions and getting no more than a weak 'chuff", The hot bowl was removed to find it half full of liquid fuel. The atomizer is clearly not satisfactory. So it was removed, and the pintle depth checked, finding it quite some distance from the bottom. Though running out of thread, this was bottomed out and the lock nut tightened. The non-return valve was also lapped with valve lapping paste and cleaned up. When assembled onto the fuel line outside the head, it now produces a good spray pattern even at the smallest pump stroke, so it is a big improvement. So, with it all back together, the hot bowl heated, and after a few false tries, it burst into life. Well not exactly "burst" as it runs in a fairly subdued manner. The whole lot still shakes badly at higher revs, so some gussets are needed in the steel base, as the I-beams are flexing in the direction of rotation. So after at least 20 years it is running again! See it at:
http://youtu.be/xKDaA6nG05o
These engines were widely used in the sawmilling industry, and also driving irrigation pumps. Their torque was legendary, being able to hang on to a load beyond all expectations. It weighs in at 3 tonnes without clutch or exhaust etc.
My engine actually saw service at a truck-stop service station on the old Hume Highway just north of Yass, NSW, where it produced all the power required for the site, using sump oil as fuel. I had become aware of its existence through contacts, but did not think it feasible to do anything about it being so large. About 1989, the opportunity arose when a friend acquired a 4-cylinder Southern Cross engine from the same location, and he offered transport. My offer of $100 was accepted by the service station, and my first trip was to retrieve as many accessory items as possible such as clutch, pedestal bearing and mount, lubricator, and the exhaust system. This much was indeed a trailer load! The head was missing from the engine.
In due course the engine reached home after two crane hires, and I set about finding a head, as well as mounting the beast somehow. Now that exhaust is quite an item. The manifold exits from the front of the engine to a 10" diameter horizontal pipe that enters the base of a 4' cast iron sphere which is the muffler, and then exits vertically via a 12" diameter pipe. The sphere is in fact a WW2 sea mine casing, which McDonalds adapted for the purpose. I had a contact in the Riverina District who actually owned one of these engines set up and running, and he offered to fabricate a substantial steel base and deliver it. When it arrived, a crane was engaged to place the engine on the base. This included a mount for the pedestal bearing as well as the exhaust. Through an advertisement in TOMM, contact was made with the owner of several McDonald engines near Tamworth which were duly acquired and transport arranged home. This included an M, and an ML complete with head. The head was transferred to my original engine and everything set up for a run. Heat was applied (I recall using an oxy torch - naughty! naughty!) and she fired first attempt. But didn't it shake! The engine, when gaining or losing speed, shook with such force it threatened to walk away. The latent power under acceleration is something to experience!
So, I was not game to run it again, and ultimately some components were robbed to further other projects. When the opportunity arose, a hole was excavated under the base and a quantity of concrete poured in to anchor it. Another job that was done was to remove the fixed pedestal bearing mount and replace it with the original hand-wheel operated clutch mechanism.
Fast forward to late 2014, and with the completion of a couple of other projects, I was inspired to get it running again. Quite a bit of work was necessary: truing up the pedestal bearing to eliminate possible flexing of the crankshaft; cleaning out the rats nest inside the engine; draining the 2" of water from the lubricator; and most importantly, making up a workable fuel pump and atomizer. The clutch is seized due to weather damage, but this is unimportant. With a fuel tank stand being fabricated, it is just about ready for a start - that is until I checked the integrity of the horizontal section of exhaust pipe only to find it rusted away at the bottom. After quite a struggle it has been removed and the search is on for some 10" diameter pipe. The original was rolled and seam welded, and that may be the only solution.
The problem has been solved by acquiring some quite heavy 220mm diameter pipe which enabled the original flanges to fit with just enough room for the bolts. In the process the muffler has been removed and cleaned out, and the I-beams around it cleaned up and rust treated, and all reassembled. The fuel tank stand has been set up and piping attached to an old fuel tank. The injector line fittings would not seal, so completely new fittings have been made and hard soldered to new pipe. Fuel has been added and apart from a leak from a cock under the tank itself, it primed with little difficulty. However, the atomizer (Injector) produces a reasonable spray pattern with a good shot of fuel, but tends to dribble with a small pump movement. Will it be good enough? Atomizer nozzles are like hens teeth.
After a couple of heating sessions and getting no more than a weak 'chuff", The hot bowl was removed to find it half full of liquid fuel. The atomizer is clearly not satisfactory. So it was removed, and the pintle depth checked, finding it quite some distance from the bottom. Though running out of thread, this was bottomed out and the lock nut tightened. The non-return valve was also lapped with valve lapping paste and cleaned up. When assembled onto the fuel line outside the head, it now produces a good spray pattern even at the smallest pump stroke, so it is a big improvement. So, with it all back together, the hot bowl heated, and after a few false tries, it burst into life. Well not exactly "burst" as it runs in a fairly subdued manner. The whole lot still shakes badly at higher revs, so some gussets are needed in the steel base, as the I-beams are flexing in the direction of rotation. So after at least 20 years it is running again! See it at:
http://youtu.be/xKDaA6nG05o