The 60 Year Demonstration

1961 International B-160 Diesel Demonstrator

International was one of the first truck manufacturers to start pushing diesel engines in light and medium duty trucks. Back in the March 2018 issue, we told you about the 1963-68 International half and three-quarter ton diesel option and how they were the first to offer an optional diesel in a light truck. That option had it roots in the story we are telling you today.

It all started in 1956 when International Harvester’s Melrose Park Plant began working on a lightweight, low-cost diesel engine. Melrose Park had been the center of International’s diesel work over the years and was commonly known as the Construction Equipment Division. We could not find exactly where the idea started but a new high speed, six-cylinder diesel was certainly on the wish list for every IH division. Most likely the biggest push came from the largest part of the company, the Agriculture Division. The Ag side was updating the tractor line in a desperate rush to beat John Deere to the draw with a six-cylinder diesel tractor in time for the ‘60s.

Ready for duty! This truck has worked all its life, but it wasn’t worked especially hard, nor rode hard and put away wet. It’s survived in remarkable original condition and the engine does not appear to have ever been apart. There’s very little rust it hasn’t been used as a battering ram like many old trucks. The odometer was showing 45,729 miles at the time these pics were taken in the fall of 2020.

At the same time, the Motor Truck Division of International was recognizing the increasing possibilities diesels might play in the medium duty truck markets. Product planning documents indicate a strong interest in the idea for the newly updated International medium duty trucks. Engines were available from outside sources, of course, but IH preferred to keep their own engine plants humming rather than write checks to other companies.

The idea coalesced into a diesel with the same packaging footprint as the Black Diamond 220, 241 and 263 cubic inch gas sixes and could be built on the same tooling. The Black Diamond engines were used in everything from half-tons into the lower-middle end of the medium duty lines and an engine of this size was perfect for the tractor lines as well. Seemed like a win-win project for multiple IH divisions.

The Master Plan

The original plan was for four displacements, two short stroke (3.688-in.) and two long stroke (4.39-in.) with the same bores, one sleeved (3.69-in.) and one non-sleeved (3.812-in.). In the sleeved category were the D236 and D282 and they were destined for ag use in tractors. The “D” indicated a diesel and the number the rounded displacement. The non-sleeved (A.K.A. “parent bore”) included the D252 and D301 and these were earmarked for trucks, marine and power units. Similar four-cylinder diesels were also designed, including the sleeved D188 and the non-sleeved D201. The D236 and D282 were manufactured, as well as the D301. It’s not clear if any (or many) D252s were built, or D201s, but the D188 was used in small tractors.


The grain bed came from Smith’s in Fargo and the sides are removable so it can be used as a flatbed when needed. The hydraulic lift apparatus is a 16,000 pound St. Paul unit powered by a PTO driven hydraulic pump.


The cab wasn’t plush but it had a padded seat and heat. In the ‘60s that was good enough. The AM radio was a dealer item.

The sleeved engines were announced in July of 1958 and began appearing in 1959 model year IH tractors and construction equipment almost right away. The non-sleeved engines were announced in October of 1959 but their introduction moved a little more slowly. The first automotive test engines were installed in 1958 and tried in a variety of truck types. This was followed by an initial 1959 production run of 228 engines that were installed into production 1959 and 1960 B-160 and BC-160 trucks that were carefully followed by IH Service, some after being sold to select customers. The IH Foreign Operations Division sent 58 of them went overseas, seeing a potential market offshore where the diesel market was strong. Along the same lines, the D201 four was contemplated for export versions of the newly introduced Scout, but rejected due to cost issues. The official announcement of D301 availability in medium-duty IH trucks came in April of 1960 but they were relatively slow to appear at dealers.

The D301 in Medium Trucks

You could order the D301 in the B-Series B-160 and BC-160 in the 16,000-18,000 pound GVW range. The B-Line had appeared in 1959 as a mostly cosmetic refresh for the much-updated A-Line that had debuted for 1957. The BC-Series was a similar evolution of the AC line, which featured a front wrap designed by the legendary International stylist, Ted Ornas, the driving force behind the International Scout. The BC line would evolve into the legendary Loadstar for 1962 and the B and BC-Series would quickly fade away.


This is the 2155th D301 engine built and is the originally installed engine. The D301 was indirect-injected with a Roosa-Master injection pump that popped the injectors at 1,600 psi. It was a four-main engine with a forged crankshaft made of C1046 steel and an 18.2:1 compression ratio. The engine weighed in at 960 pounds, about 120 more than the 304ci V8. The camshaft and injection pump were all gear driven. Interestingly, the camshaft profile was shared with the G301 gas version of this engine that debuted at the same time. IH engineers said a diesel-only cam didn’t make enough difference in power to justify the expense of producing it. Oil capacity was 9 quarts in most truck applications and a full-flow, water-to-oil-cooler was used. Because the trucks used a Hydrovac brake booster, a very large cast iron vacuum pump was used and a large dash mounted vacuum gauge was included.

With the Loadstar intro, the D301 was relegated only to 16,000 pound GVW trucks but became an option in the smaller Schoolmaster busses as well as the 1600 4×4 Loadstars. Beginning in 1963, it was offered as a Special Equipment option in the Light Line, the half to one-ton light trucks and the Travel-all. There were a few specialty installations as well, reportedly a few Metros and other panels. Palmer offered them in a marine conversion starting around 1963 and they were seen in IH combines as late as 1976.

Anatomy of the D301

The D301 was rated at 112.5 gross horsepower at 3000 rpm (92.1 net)  and  228 net pounds-feet of gross torque at 1600 rpm (211.8 at 1400 net). The VIN plate on early trucks often lists power at 107 at 2700 rpm gross and 91.5 net. Either way, that’s not a power house but it lived at the bottom of the optional diesel food chain and was recommended for short-haul, low-speed, moderate load situations. A 131 horsepower Perkins D354 was the next step up the food chain starting with the Loadstars in 1962. The Perkins was a hotrod compared to the D301 and therein lies the “issue” with the D301. Later in the ‘60s, International’s DV462 V8 diesel would be added to the Loadstar line (and others) and the smaller diesel sixes would fade away.

The power and torque graph from June of 1960 shows the modest output of the engine.

An SAE paper from November of 1960, “Diesel Engine for Medium Duty Trucks” (paper S269) listed a top speed for D301 powered trucks of 52 mph at 3000 rpm with a 6.33:1 axle ratio. They did not recommend an overdrive gearbox, presumably because the engine didn’t have the juice to push a loaded truck down the road in O.D. We couldn’t find an overdrive gearbox listed for the D301 trucks all the way to 1968.

This Old Truck

What you see featured here is a 1961 B160 truck, a B162 to be exact. In that year, there were actually several GVW levels in the B-160 range, the B-160 at 16,000 pounds, the B-162 at 18,200 pounds, the B-164 at 19,700 pounds and the B-165 at 18,200, plus five wheelbase lengths from 129 to 189 inches. There was a 4×4 B-160 on the 129 inch wheelbase with a 16,000 pound GVW. The books show the D301 as available in all those GVWs but it appears IH learned that the D301 didn’t have the suds for those higher ratings. Regardless of the actual GVW, all the trucks were badged “B-160.”

”Everything works on this place,” Bryan told us. Well it’s obviously not being flogged but it’s earning it’s keep. It’s showing a bit over 45,000 original miles and it’s still as hale and hearty as it was in 1961.

This B-162 features the 18,200 pound GVW on a 153 inch wheelbase. It was shipped to the Fargo, North Dakota, IH dealer in early September of 1961 and is among the last of the B160 series trucks built before the Loadstar debuted and replaced them. Beyond the D301 engine, it was ordered with the T15 4-speed transmission and 2-speed RA126 axle with 5.83/8.11:1 ratios. It came in #902 Whitecap White with a standard cab but with the better foam seat, armrests and visors ordered a-la-carte. Heaters were an option in that era and this has one. The dealer installed the roof-mounted radio.


For all these years the truck continued to wear it’s demonstrator graphics. They had faded but were a more distinct than the photography would lead you to think. Tim  took careful measurements and had decals made up to place over the old hand painted lettering. They are slightly offset so you can still see the outlines of the original hand painted lettering. Yep, this is definitely the longest demonstration we seen… 60 years and counting. So far so good! Two thumbs up from Tim.

When it arrived at the dealer, it was fitted with a fuel oil delivery tank and used as a demonstrator for some period of time, hence the “International DIESEL ENGINE” on the hood. Apparently it took a while to sell but ended up with a Page, North Dakota, farmer who installed a flatbed with a grain box and hydraulic lift. It was later sold to another local farmer who mounted a water tank on the flatbed. It ended up on a vegetable farm in Michigan in 2003, still used as a water truck. Current owner Tim Bryan bought it in 2018. It lives a dual life as a “working collectable” on the Bryan’s small farm.

The Line Setting Ticket is still attached to the sun visor on the truck and clearly shows the build configuration. If you have an old IH truck and the vehicle copy is missing or illegible, you can order a copy of the original sheet that ran down the line with the truck from the Wisconsin Historical Society. Not only will it tell you what components were used, it will tell you the day it was built, and where it was shipped. It’s the blueprint for a restoration.

There have been a few interesting changes made over the years. At some point early on, the T-15 4-speed was replaced by a 5-speed transmission. Tim isn’t sure which 5-speed, but we think it’s a NP540 unit. Tim doesn’t know when it was installed but it’s clear it was installed a long time ago and maybe when the truck was still fairly new. Along the same lines is a later fuel tank, a type found on various models of trucks in the ‘70s and mounted on the opposite side of the original tank.

The 1961 BC-160 top, the role model for the later Loadstar line, and the B-160. Both had the D301 on the options list.

As you might have guessed, the D301 was not a popular option. The standard 264 Black Diamond gasser outpowered it by nearly 50 horsepower and while the diesel delivered 12 mpg vs 8 for the gas, the price premium for the diesel (about $100-120, roughly a grand in 2020 money) too a long time to pay off on top of the severe performance penalty. In light and moderate use, the D301 was a good engine. Because of it’s low  output, it had to be flogged constantly and that will have negative reliability effects on any engine. To the extent the end has a “bad rap” in any of the venues it was used, that is the root cause.


Wisconsin Historical Society
McCormick-International Harvester Collection 

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