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Piston Koetherizing Service and Mobile Engine Machine Shop

Today’s feature image contains a traveling machinist from Motor Parts and Equipment Inc., with a late-1930s Chevrolet panel truck outfitted with engine reconditioning equipment. This promotional photo was taken on November 3, 1948, at Jim Harmon’s Mobil service station located in Tacoma, Washington.

In the 1930s to early-1960s a number of larger automotive machine shops had a machinist with a truck and equipment that would visit service garages and perform reconditioning and machining services for parts that were re-used for engine-in-chassis reconditioning jobs.

The inside of this Motor Parts and Equipment truck (below) is equipped with two piston “Koetherizing” machines from the Koppers Company, which manufactured “American Hammered” piston rings. Behind them on the left is either a Model “A,” “B” or “C” Ford four-cylinder engine powering an air compressor that kept the large vertical compressed air storage tank in front of it filled. The pressurized air powered a pair of piston “Koetherizers.”

Editors Note: Tomorrow is the Forth of July holiday and due to it The Old Motor will not be published . We will return again on Thursday morning July 5, 2018.

These machines blast a jet of compressed air and steel shot at the inside of a worn piston skirt one side at a time perpendicular to the piston pin bore; at the same time the nozzle moves up and down while the piston rotates from side to side. The machine then blasts the other side of the skirt and the peening action which takes place on both side, expands the piston. The result is a reconditioned piston that returns to its slightly oval shape and size.

When combined with correctly honed cylinder bores and “Koetherized” pistons fitted with American Hammered rings and oversized piston pins the reconditioned assembly could perform for up to fifty-thousand miles of additional service.

In front of the Ford engine on the floor is a disassembled Sunnen in-car crankshaft grinder that could be used to regrind damaged or worn connecting rod journals. Combined with undersized rod bearings and a thorough crankcase cleaning a correctly reconditioned crankshaft could be placed back in service for some time.

Share with us what you find of interest in these photographs by the Richards Studio courtesy of the Tacoma Public Library.


21 responses to “Piston Koetherizing Service and Mobile Engine Machine Shop

    • Not much hotter than today, just got back from picking up some parts in Keene, NH, and it was 102 degrees about 1PM. Must have been about 110 inside the 1800s. Now I know why some of the old timers call the cars a Swedish sauna. Need to finish restoring the original AC system and and install it.

      • I had a 1960 PV544 back in the 60’s that refused to have it’s heater controls shut down in the summer. Running a hose loop from the engine hot water output directly to the return input in the Summer sort of helped but not much! The car was black which did not help in the Midwestern sun! It did help prepare me for the heat in Vietnam!
        Persevere, my friend!

  1. I’m struck by how forgiving those engines must have been. There must have been limits to the precision you could get essentially stretching the pistons. I can’t imagine that a modern motor would tolerate having the pistons fluffed up and the crankshaft trimmed in place.

    • Those engines were pretty lightly loaded and didn’t make much horsepower or run at high RPM. Because of that you could get away with a lot of what today wouldn’t be used on a lawn mower. Pistons and valve guides were often knurled and then resized as a regular part of an “in chassis” or budget overhaul and some shops still have the tools to do these “reworks” of what are worn out parts.

      • Back in the eighties, I watched The Great Race roll into Wilkes Barre and got a chance to talk to a guy working in a mid 20’s American LaFrance fire engine. Huge T-head six, with individually cast cylinders with integrated heads.

        He told me that, a few days earlier in the race, they’d cracked one of the cylinders. They just took it off, pulled the piston and connecting rod, patched over the hole so the motor wouldn’t throw oil everywhere, and kept driving on the remaining five cylinders.

        As I say, remarkably forgiving.

  2. This is fantastic.My compliments to the chef.
    I guess the engine is part of a exchange service.
    And what means “Fixed Load” that is painted on the side down low.
    And scope out the beanie/garrison hat imparting a feeling of military esprit de corps and elan.

    • “Fixed Load” probably indicates to state trucking-weight authorities that the truck is not carrying freight but rather an unchanging load, i.e., the machinery.

  3. Antique model airplane engines used cast iron pistons in cast iron cylinders. No rings were used, instead they relied on close fitting parts. Cast iron will swell when heated enough. I used to overhaul these engines by heating the pistons until the close fit was re-established and compression returned.

    The same phenomenon is a problem in Model T exhaust manifolds which will warp over time because of them growing and the asymmetric design.

  4. Trying to understand what was taking place here, I found the following article in Popular Science from June 1941 which has diagrams of the Koetherizing process. Replace the two instances of the word “dot” with a period to see the article below.

    https://books dot google dot com/books?id=UycDAAAAMBAJ&pg=PA134&dq=koetherizing&hl=en&sa=X&ved=0ahUKEwj6zJzV9YzcAhWMh5AKHeaIBmMQ6AEIJzAA#v=onepage&q=koetherizing&f=false

    Delving a little deeper, the Koetherizing process was introduced to the repair market in 1936. Emil A. Koether was the inventor, and he submitted his method for a patent on December 31, 1935. The patent, US2041355A, was granted on May 19, 1936, and it can be seen on the Google Patents website. This expanded on his earlier patent, US2032020A, that was granted in February 1936. Koether was granted at least 12 patents during his lifetime including several for piston rings.

    Emil A. Koether, 1892-1956, was an engineer, but I did not find what college he graduated from. He worked at the American Hammered Piston Ring Division of the Koppers Company for much of his career. He was a foreman, an assistant manager, he was on the research staff, and eventually he became the technical assistant to the vice president and general manager of the division. He also published at least two articles regarding the grinding of gears. Ads for “Koetherizing” can be found in issues of Motor Age in April and June 1940, and in many newspapers from 1936 – 1955. Use of this process seems to have continued well into the 1960s if not later, and the process was also used outside of the United States.

    I also looked to see if there was a direct connection between Motor Parts & Equipment, Inc. and Jim Harmon. Both business were located on Jefferson Avenue. The address of Harmon was 2518 Jefferson in 1947 and 2112 Jefferson in 1949. Motor Parts & Equipment was at 2502 Jefferson in 1947 and 1745 Jefferson in 1949. The president of Motor Parts & Equipment was Parker Tottler who in 1960 became one of the founding members (Trustees) of the Washington State Automotive Wholesalers Association.

  5. RE: The Chevrolet Panel truck with “Portable” Piston refurbishing (Shot – Peening , in this case) equipment: I would venture an accurate guess that the: “Model “A” Ford Engine driving an Air Compressor” would not be practical in the engine’s seen location — as this would require the compressor’s parts to be dangling out in the left lane ! Instead, the VISUAL evidence obviously suggests that the Ford Engine’s “Bell housing” has nothing connected to it! (See for yourself). How can this be, (you ask? ) Simple: you are looking at a: “Smith Motor Compressor” from Bowling Green, Kentucky! The Ford Engine’s end pistons become its power source , thus, somewhere (up to) a 20 Horsepower 2 cylinder in- line engine, firing at even 4-stroke intervals , the other two cylinders are blocked off by removing their cam followers and leaving their 4 valves sealed & non; operational, making the 2 inner pistons that rise & fall together, as usual , into a 2- piston AIR Compressor “lower end”. The engine reveals: A Model “A” Only , ( Intake, exhaust, manifolds, side (valve) cover are only “A” Model. “B” engines are different (including their distributor & carburetor Model “C” engines are the same Model “B” engine with a slightly different cylinder head design designation. THIS truck’s Smith Compressor “Appears to have a Propane or Butane conversion – “inlet “instead of its usual Zenith carburetor. The radiator’s (R.H.S.) view— is “covered up” by the vertical (BIG )air tank behind & to the right of the Smith Compressor Note the Pilot Valve on the air tank” this controls the throttle opening for “Load & Unload” and Overtakes the 2 cylinder air compressor’s ROOF governor (Fan belt driven), as necessary . The TRICK is the Smith Motor Compressor HEAD (which replaces the Model A 4 banger head) the advantage of the Smith unit is that it creates air immediately, with its huge volume (suitable for Jack hammering!!!) —(which is exactly what’s needed for Shot- Peening Service! The other advantage of a Smith unit is: That it is way more compact!!! The Smith company remains in business today, — except that they use one V-8 cylinder head as a motor and the other head as a compressor. Same results : Compact, lots of air quick, and way less expensive! Just like a Model A or A-A Ford vehicle is Edwin W.

  6. 1938 Chevrolet panel truck, in case anyone was wondering. I enjoyed all of the comments above. Mr, Edwin Winet’s was an education in itself, thanks! I recall my dad explaining the shot peening process, and also engines refitted for air compressor use as described.

    Also, thanks to Mr. Ace Zenek for the added links and historical information on the Koether Process. It fills in interesting detail to an interesting topic.

  7. Around 1955/57 we had a mobile crank grinder working in the Salem Or . area. The operator would pull the starter and install a motor driven shaft that turned the crank. Never saw i t operate but would think that it worked well for one journal but may be not all.

  8. When I was in HS I bought a 55 Plymouth 273 that had had an in car crank re-grind. Didn’t last long with a 17 year old driving.

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