Onan CCKM-MS/2050G Engine Repair

[Ulma Doctor]

I have another engine to repair from my last client, this time an Onan twin cylinder engine.
the engine is difficult to roll over, there appears to be a valve that possibly may be bent
i took pictures of the engine and transmission.
this engine is being used in a garden mule , from the owners description
a Delco 65Amp Alternator was added





here is the first video in the series...

more to come as i get deeper in!

 

[cathead]

Thanks for the post and video too. I will be following along to see what happens here.

I like protuberance. By the looks of the accretions on the intake valve, the rings must be not in the best of shape.
As far as the engine not turning over freely, there must be something else at play here. Normally, an engine like that
with the heads off would be loose as a goose. I'm sure you will get to the nitty gritty of things. I wonder what the oil
looked like and did it look like it was cared for? Did the oil look like the ace of spades?

Good luck with your project.

 

[Martin W]

Hi Mike
Looks like you have your work cut out for you on that .
How are parts to get ?
My Father in Law picked up the same engine, only older . He was going to use it on an old Yazoo mower. When I pulled it apart it had water in the cylinders also. None of the valves that looked like that. LOL. He didn't want to put any money into it so we just honed the cylinders and cleaned everything up. The cylinders were scored pretty badly. Should have had it bored....
It runs, but it needs to be rebuilt.
Cheers
Martin

 

[Ulma Doctor]

Thanks for the post and video too. I will be following along to see what happens here.

I like protuberance. By the looks of the accretions on the intake valve, the rings must be not in the best of shape.
As far as the engine not turning over freely, there must be something else at play here. Normally, an engine like that
with the heads off would be loose as a goose. I'm sure you will get to the nitty gritty of things. I wonder what the oil
looked like and did it look like it was cared for? Did the oil look like the ace of spades?

Good luck with your project.

Hi Cathead,
The oil was very dark and smells like gas
The cylinders are not scored, no ridge is present at the top of the cylinders
Disassembly will for sure tell the issues with the engine!

 

[Ulma Doctor]

Hi Mike
Looks like you have your work cut out for you on that .
How are parts to get ?
My Father in Law picked up the same engine, only older . He was going to use it on an old Yazoo mower. When I pulled it apart it had water in the cylinders also. None of the valves that looked like that. LOL. He didn't want to put any money into it so we just honed the cylinders and cleaned everything up. The cylinders were scored pretty badly. Should have had it bored....
It runs, but it needs to be rebuilt.
Cheers
Martin

Hi Martin,
Yeah, the engine has seen better days
With a little luck, she’ll be back in action soon!
I have a spare engine the owner sent with this engine as a sacrificial offering
I have not tried to source parts yet, but i have seen remanufactured long blocks for about $500 if the SHTF

 

[Ulma Doctor]

i was able to teardown the engine yesterday
i hooked chain and a come-along to a hitch point on a huge glue-lam beam that spans my garage for a lifting point
i separated the oil sump from the block, by hoisting the block off the sump and rotating it 90° to sit on what is the transmission bell housing
the engine was locked up to where i couldn't gain access to the con rod bolts or the flywheel retention bolt
i was at a point of no return, so i went Neanderthal with a drift and 4lb single jack to firmly persuade the flywheel to rotate
after a few blows, swingin' from behind the ear
the force finally advanced the crank to where i could get a con rod bolt removed from both rods
after removing the 2 bolts, the engine seemed to loosen only slightly
so i kept at percussion.
after another 10 minutes of persuasion, i was able to just fit a socket and a strategically bent piece of 1/4" keystock to act as a low clearance breaker bar.
once i got the #2 cylinder rod cap off, the problem with the engine revealed itself
the engine suffered what would be the equivalent of a spun connecting rod bearing
the cause of bearing failure is almost invariably, lack of lubrication.
this was no exception.
since these Onan engines use aluminum connecting rods, Onan feels it is unnecessary to use conventional shell bearings
their lack of replaceable bearings requires rod replacement

the #2 connecting rod physically welded itself to the crankshaft as seen below
you can see a horizontal line where the oil port transverses the crank, this line is a 2mm wide band of aluminum,
which used to be integral to the connecting rod.


a look at the con rod journal


and the cap



otherwise the pistons and cylinders look serviceable
here is #1

here is #2

the crank may be done for ....

i was able to rotate the crank 360° without bind, so i wet to look for the flywheel retainer bolt
wouldn't you know, the previous shade tree masochist (my term for untrained mechanic) had broken the 3/8"-16 retention bolt off flush with the bore.

i'm gonna have to drill into a low clearance area, but i think i have enough room to do it

sit tight,
i'll post what happens next soon!

 

[cathead]

The crank may be salvageable if you can get the aluminum galling removed and put a micrometer on it...

 

[mattthemuppet2]

crikey! I wonder who thought bare aluminium as a bearing was a good idea? If you can get the crank journals into some lye/ sodium hydroxide (drano) that alu smeared onto the crank will disappear in a jiffy.

 

[Ulma Doctor]

crikey! I wonder who thought bare aluminium as a bearing was a good idea? If you can get the crank journals into some lye/ sodium hydroxide (drano) that alu smeared onto the crank will disappear in a jiffy.

that's great advise!
thanks for the tip!!!

 

[FOMOGO]

I agree with cathead, the crank will probably clean up fine. Just need to make sure it's straight, and not tweeked due to rod failure. New oil pump, measure up piston and bore to see if you can run the original piston. Sounds like you may be able to with no ridge showing. Hone, new rings, and off to the races. Maybe a 100 shot of NOS to make things interesting. Cheers, Mike