I have a 9k grader with low compression and blue smoke. I’m thinking about a D318 engine swap vs rebuild the old motor.

Looking for a little info:
1) can someone outline the changes I’ll need to address? For example: is swapping to a new oil pan
2) What should I expect to pay for a used power unit? I see cores selling for $500 but I don’t see any running engine out there in this class
3) is it worth considering to find a “good” D4600 to put in.

Dave

I would say it won’t be easy. I would start with a parts book for the early 8T graders and the one for your 9K and compare gasket part numbers for block to clutch housing and oil pan to block. If those match up, then you’re down to physical dimensions like distance from clutch housing back to the bolt holes in the chunk in the middle of the rear axle. For sure you need a grader oil pan to support the engine.

I have seen a mention here of a 212 that had been swapped from the D3400 to a D311 or the other way around but don’t really know how comparable the #12’s were across that 1947-1948 model change. The oil pan may be the only difficulty. That said there should be some grader engines out there as many of them as were made.

Thanks for the suggestions. Sounds like I have some research to do.

If you got a D318 out of a grader it wouldn't be that bad. The oil pan and bell housing are the main mounting points that you need to be concerned with so a crawler or stationary engine would be a bit more work to fit up. The tin will bolt up easily. It is a bit of work, but it would make a nice grader when you were done for sure. I was pretty lucky that my D4600 was in good shape, may have to fire it up today and listen to it run now that I have read this.

"JoeG" wrote:

If you got a D318 out of a grader it wouldn't be that bad. The oil pan and bell housing are the main mounting points that you need to be concerned with so a crawler or stationary engine would be a bit more work to fit up. The tin will bolt up easily. It is a bit of work, but it would make a nice grader when you were done for sure. I was pretty lucky that my D4600 was in good shape, may have to fire it up today and listen to it run now that I have read this.

Is the distance from the bell housing to the axle mount the same between the D318 & D4600 (on a grader engine)?

You’ll have to find out and let us know!

Like I said earlier I’ve heard of an old/new engine transplant in a 212 but never in a #12.

I may have found a power unit for a 12 grader but it may be October before I get to see it I’m person.
I’ve been promised it’s a “runner” but I’ve heard that before.

Hey just curious about what serial number your machine is ! Thanks Alan

If you are asking me my Cat 12 is 9K 9071 and was a government owned unit, I bought it on the GSA auction. It needed a ring gear and the pony was full of water, well ice really, it was February here. I also put the decompression rod seals in the valve covers and new gaskets there but other than that, it is in great shape. it was rebuilt in 1968 at Schenectady Army Depot according to the metal plate on the cab, and the hour meter shows 1,400 hours, which may be correct. It came off a federal wildlife refuge near here and surely didn't see much use.

My Cat 12 is 9K8140.



My understanding is that makes it from 1944. Bought it about 14 years ago from the widow of a guy who called it lucy. I'm thinking you can guess why. I've done a bit of work to get it a bit more reliable:
Rebuilt the Pony & starter (my understanding is the PO pulled start it with a truck for years)
Replaced the Radiator
Replaced some fuel, brake lines, Fuel linkage and other bits and pieces

it's a hard starter. Seams to have low compression and I'm debating if this motor should be rebuilt or replaced. any advice on running a compression test, or a leakdown test?

BTW: I back near the Grader, and its 17" from bell parting line to the center of the oil pan bolts on the final drive.

Dave