The Ford Osco Engine/Engine Compartment

[bob mitchell]

    One of the original engines that the New Jersy built Newporters (I say New Jersy because if you look at the "History" Forum on page 11 of Forums, you see that the East coast boats changed manufacturing venues a few times) came with was the 59 horsepower Ford Osco 172 cu. in. Diesel. Osco, like Lehman, would take a Ford engine and marinize it. The Ford 172 cu. in. Diesel was a ubiquitous tractor engine, so after market rebuild components are readily available at very reasonable prices. The only component that is unavailable, as far as I know, is the gear driven raw water pump. If I recall correctly, this engine was built in England by Perkins for Ford.

      My boat, hull #113, built in 1967, originally came with a Ford Osco Diesel 172, but was replaced with a Ford 192 cu. in. Industrial Diesel in 1977. The principle difference between the 172 and 192 is about 7.5 horsepower (at 1800 rpm) because of the larger engine bore (3.16 "versus 4.14", but the stroke is the same at 3.60") - both had a 16.8 to 1 compression ratio, and the fact that the 192 has an engine balancer, driven off a gear in the middle of the crankshaft, thats sit under the engine in the oil pan. Aside from that, there is no difference in the rods, crank, block, head, and Roosa Master fuel injection, EXCEPT FOR THE FACT that there are so many tractors with the 172 in them that there are aftermarket component manufacturers at good prices, but the 192 was an industrial engine, with applications like fork lifts and large water pumps, but not enough of them were built to justify aftermarket parts. To express that idea in real terms, an after market piston for a 172 cost about $80 bucks, while a piston for a 192, only available from Ford, costs $200 a piece, and only available in "standard" size.  The price difference is like that for all components.

        I quoted "standard" size above, refering to the diameter of the piston (bore). Often, when you rebuild an engine, it is because some component has disentegrated, like a rod bearing, and the metal shrapnal has been carried by the oil, circulating in the engine, to places you don't want it to be. In my engine's case, the return fuel line (not all the fuel from the injection pump is injected into the cylinder - some returns to the fuel tanks, and in doing so helps lubricate the injector pump and injectors) which is under the valve cover, broke, and the diesel dribbled down the push rod oil gallery into the crank, dilluting the oil until the number four rod bearing went bad, maybe siezed, and shreaded. Then the piston kept banging up and down until the rod was distorted to the point that I have to get another one for the rebuild.

    Well, back to the "standard" size - the cylinder walls can wear as well, and often have to be rebored to a slightly larger size (and then rehoned to create a texture microscopic valleys and ridges that allow the piston rings to "seat"-

and it is important that during this "seating" process your injectors are working correctly, ie delivering the correct amount of fuel, or the rings will not seat and all rebuilding is for naught - so be sure to have your injectors checked out while the rest of the engine is being rebuilt. In old engines like the 172, injectors open to inject the fuel based on the cylinder pressure overcoming the opposing the injector spring pressure, so the injector spring pressure has to be right, and the tiny injector nozzle holes as well.)  Back to "standard" - the standard size is the original bore. If you have to rebore you can get .010, .020, .030," oversize pistons and rings. The same applies to bearings, as long as the rod and crank journals are not out of round beyond what grinding will bring back into round - for instance my crank came back into round at .020".

    When the cylinder walls get too thin to rebore you have to put in a cylinder "sleeve", and then bore it to the proper size. The 172, the data sheet states, came with a removeable dry type sleeve anyway. My 192, which was installed in 1977, and rebuilt in 1999, had sleeves installed in it, but one of them is gouged, and there is a lot of wear on others, so I will have to put new sleeves in mine. To put new sleeves in 4 cylinders where I live (down South) is about $500 - $600 because the machine shop has to bore out the old ones and press in the new ones, as well as the cost of the sleeves.

     

        At any rate, to make a long story short, I have decided, because of the inavailability and expense of 192 parts,

to resleeve back to the original engine bore of 172, which will give me a thick walled (ie can be rebuilt at least twice more) cool running detuned engine with an engine balencer to make it run smoother (the original 172 did not have an engine balencer).  The parts will be readily available and inexpensive. The fuel injection pump may have to be slightly adjusted, but maybe not. Jerry, up on sand mountain (Diesel Fuel Systems) does stuff like this everyday, and is checking his specs - to redo the injector fuel dose is $129 and is Jerry's specialty.

     The idea to resleeve back to a 172 was not my idea. Gary Cooper, down near Mobile, who deals with a lot of maine engines, said he had done 192 to 172 conversions for several of his customers because of the piston cost and parts unavailibility for the 192.

UPDATE; I WROTE THIS A MONTH AGO, BEFORE I FOUND OUT MY BLOCK WAS BAD, BUT FOR SOME REASON IT JUST GOT POSTED - BUT THERE IS GOOD INFORMATION SO I WILL LEAVE IT FOR A FEW DAYS.