Sexton R975-C1 a mess

[LRDG]

At the Oshawa military museum, we got the front covers off a sadly neglected R975-C1 out of the Sexton. We were expecting pistons rusted into bores but it was much worse. 5 of the 8 articulated rods are broken at the big ends (which, to my surprise, are actually the small ends because the knuckle pins are much smaller diameter than the wrist pins). The master rod bearing is also toast with about 1/16" clearance.

A number of pistons are all smashed up and each broken rod smacked the bottom of its liner on both sides as it was thrashing around so that the liner is mushroomed out, making it a pain to pull the jugs. The crank is a mess but surprisingly the crankcase looks intact.

Very disappointing. It probably makes a rebuild out of the question as we need a complete rotating assembly and probably 9 jugs. It's probably best to part it out and install a Detroit diesel to make the old girl mobile again.

Malcolm (using Cliff's sign-on)

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[Hanno Spoelstra]

Malcolm,

That looks like serious damage, but for the C1 especially many spares can still be had. Maybe you spend more on the overhaul of the R975 than on a used diesel (ugh!), but you will save a lot in not having to convert the Sexton for the other engine to fit in. You will need to make engine mounts, cooling system, and change fire wall, prop shaft, fuel system etc. etc. - this is a huge job!

If I were you I would try to source the parts for the radial and find an aircraft / engine mechanics school and ask them to do the overhaul as a teaching project. I'm sure the students will like the ride in the Sexton afterwards!

Hanno

[David Dunlop]

It might also be worth checking the aviation market for a complete engine that has reached the point of being too expensive to rebuilt for flight purposes, but will spec out just fine for a land vehicle.


David

[jdmcm]

I would recommend you talk to Carl Brown of C&C Military in England, great guy to deal with and tons of radial and Sexton experience and probably parts, if not complete engines. Hanno is right, converting to a liquid cooled diesel would be on par with simply replacing the radial. You could also try Andy Sanclamente at Northeast Military Vehicle Services near Boston, another great guy with lots of radial experience. I am pretty sure he is not currently doing restorations or rebuilds but he would still know where to find what you will need.

John

[Perry Kitson]

Bob Phillips, and Staman Trading had lots of parts for the C1's. Radial parts in general are getting hard to purchase (notice I said "purchase", there are parts out there, but collectors have been stocking up).
Converting to a more modern engine is doable. About the only diesel that will fit (and give you decent power) without modifying the hull is a 6V53 Detroit, about 300 HP with a turbo. You can use the original drive shaft, rear engine mounts, and clutch linkage. You will need a custom built rad, custom front engine mount, electric fans, No. 2 bell housing, flywheel, clutch and numerous linkages built. This will all fit in quite nicely, but will require many hours of machining and fabricating

[LRDG]

So I sense some disapproval of the diesel swap. It's not our choice either, but I understand funds are a bit limited for what may be a $10-15,000 repair based on some prices presently on the North East Military site (and $23,000 for a C4 engine).

We have spare Detroit diesels here (although I need to confirm if any are 6V53's, Perry) and it sounds like a very interesting project to me. I really enjoy the design/fabrication stuff.

Anyway, I am working full time at a "real" job right now, but retiring in April so I will have more time then to follow up on the leads you all gave me above. In the meantime, we will continue dismantling to find out the full extent of the damage.

[Hanno Spoelstra]

Originally Posted by LRDG

So I sense some disapproval of the diesel swap. It's not our choice either, but I understand funds are a bit limited for what may be a $10-15,000 repair based on some prices presently on the North East Military site (and $23,000 for a C4 engine).

We have spare Detroit diesels here (although I need to confirm if any are 6V53's, Perry) and it sounds like a very interesting project to me. I really enjoy the design/fabrication stuff.

Anyway, I am working full time at a "real" job right now, but retiring in April so I will have more time then to follow up on the leads you all gave me above. In the meantime, we will continue dismantling to find out the full extent of the damage.

Malcolm,

It's not so much disapproval, we're just trying to change your mind.... Seriously, for a museum piece I believe one should try to keep it in it's original configuration. Frankly, the fact that you enjoy the design/fabrication stuff cannot be a decisive factor in the decision to fit it with a diesel. Unless the Sexton is your own, that is - you could even paint it pink
I think there are several options to repair or replace the radial nearer to the museum than having to go to the US or UK - please ask Cliff to check his PMs.

Good luck with your endeavours and I hope you get this Sexton running again.

Regards,
Hanno