Photos of 5E engine in question.   We THINK it may be from a grader, built in Australia by Steelweld, under licence to Caterpillar.   I know several machines or impliments were built under licence in Australia and New Zealand.    Still not 100% sure!

So from the NPR book down at the bottom D6600 power unit, is the D6600 the engine in the 4r and 5r D6's? If that is correct this would be a power unit engine used in a early Cat 12 grader, if the bits Cable Control has gathered are right. But at this time it is back to was the engine original or a replacement at some point.

Back to the mystery of what all happened during WW2. Thankfully they took the just get it done policy.

quote ? - During the 1930's to 1950's the Serial Numbers 2S5501 and up, were reserved for "Miscellaneous Engines". These were engines supplied to clients outside Cat factory production.
The largest consumer of these miscellaneous 2S5501-up engines was Waugh & Josephson, Caterpillar agents for the State of New South Wales, Australia - who used these engines in Australian-built Caterpillar Auto Patrol graders.
More than 500 of these Australian-built Cat Auto Patrol and Cat 12 graders were produced by W&J between 1936 and 1945.
,
Australian licence built Waugh and Josephson Graders have S/No's--according to Owen Triggell's actual W&J data-- ranging from 5E 5628 to 5E 5840.
These 5E S/No's of engines are for No 10 and No 11 Speed Patrols and are therefore D4400 and D6600 engines with S/No's mixed thru the 5E 5628 to 5E 5840 range of numbers.
As an example, a No10 listed has a D4400 S/No 5E 5792 and a No11 has a D6600 S/No 5E 5793---consecutive S/No's. This is repeated thru the range given with a few No12's in there as well.

Isn't a D6600 a three cylinder though?

Paul.

D6100 and D6600 are both three cylinder engines, the engine in the photo's is a six cylinder, at aguess it is the same engine that is fitted to a D6 4R or 5R series.

The radiator grill spaced out from the radiator makes me wonder if it has a sump oil cooler sometimes fitted to stationary engines.

Wombat

The radiator part number (9B2000) corresponds to the 9K 6 cylinder D4600

From the pictures I would guess the same engine as the 4r and 5r used. But don't know the number and saw power unit and asked.

Hi, Folks.
If my understanding is correct, Caterpillar had a policy of matching engine numbers to machine serial numbers back in those days, even with the built-under-licence machines so, if it was in a machine, it would likely have been a machine with a 5E prefix. There's notta lotta them.

My guess would be a stand=alone engine for stationary power or as a power plant in some other manufacturer's machine.

Doesn't do a whole lot to solve the mystery, does it?

Just my 0.02.

as you can see the serial mumber is 5E5990 is a D6600 power unit and 5E5990 dosnt fit in the number for australian built graders , serial number tag swapped from a d6600 engine to the d4600 engine ?

That is definitely a D4600