M18 engine ya or nay?

1811woody · #1 12-25-2021, 01:16 PM

I put this in the general topics and not just kohler, I wanted to hear feed back from all sides. All of my cubs have kohler engines 2 m18 and a command. As far as the m18s my 1811 needs at the very least a ring kit and my 1872 a gasket set and maybe rings. id like to know your thoughts as far as longevity on the engines good? bad? worth rebuilding? Special precautions when rebuilding? Suggested rebuild kits? Any input is apreaciated.

R Bedell · #2 12-25-2021, 08:09 PM

My suggestion is to rebuild the M-18's. IM0, the Magnum series were excellent engines. Advice????, take you time and do it right.

Farmall450 · #3 12-25-2021, 09:35 PM

Quote:

Originally Posted by R Bedell

My suggestion is to rebuild the M-18's. IM0, the Magnum series were excellent engines. Advice????, take you time and do it right.

What he said ^

ol'George · #4 12-25-2021, 10:37 PM

I agree 100%, the m-18 was the latest and best of the opposed twins.
The KT17 series II is also a good engine.
As far as a "gasket kit" well they used a sealant rather than gaskets, other than the head gaskets.
Some used a gasket on the PTO end cover plate, later ones used a sealant.
As far as a "ring kit"
You open them up and check the clearances on the crank/rods and check cylinders for out of round, egg shaped, taper, and scoring, using precision measuring tools. (Dial bore gauge is ideal) second best it a telescoping gauge/micrometer.
in experienced hands, both give accurate results.
Anything else is an approximation.
If within specifications a re ring is acceptable, if out of specifications a bore/hone to over size is required.
Also the valves need addressed as to their condition and action taken if needed.
The valve lash is set by grinding the valve stems as they have no other adjustment.
Also crank seals are replaced.
Reading the genuine kohler service manual covers everything needed and it is a free download.
Apologies if you are in the know of these things.

Best to have a machine shop check measurements, if you are not experienced or have the tools.
I hope this gives you some idea of the repair approach.
By all means order nothing till you see what is needed.

1711Cub · #5 12-26-2021, 07:12 AM

Two detractors to the M18, since I own 2 and a M20...

They are thirsty, but smooth and torquey.

They have a weak governor gear, which can ruin the engine either by overspeed or damaging the block when they break.

Other than that, I love them. Just change the oil and filter, keep the cooling fins clean and run them for several thousand hours..

Oak · #6 12-26-2021, 08:22 AM

I agree with the others, rebuild the Magnum if needed.

1811woody · #7 12-27-2021, 05:17 PM

Thanks for the input guys, so be it rebuilds are the route ill go.

jsoluna · #8 12-30-2021, 07:12 PM

I would add that depending on who you talk to, a lot of people advocate for repower with a Command vs rebuilding the Mag twin because internal parts are more expensive and getting hard to find. I personally would rather own the Magnum over the Command just because I think they are great workhorses and very simple and reliable. They are less finicky about overheating as well. They are thirsty though.

If the M18 just needs a rebore and/or hone and set of rings, pistons, and valve work, it shouldn't be too bad. Make sure to pin the governor shaft so it stays in place before putting it back in service.

I find them enjoyable engines to operate and work on.

1811woody · #9 01-01-2022, 09:32 PM

I hear the govenor is a real engine killer. Is the pin the reason?

ol'George · #10 01-02-2022, 08:11 AM

The governor shaft is in a plug, that is pressed into the case.
A limited number of these plugs were on the small limit of tolerance and a few of the case bores were on the high limit of tolerance.
If the engines were run overheated because of plugged cooling fins, or other reasons, some would drop the plug into the crankcase, or it would fall outside of it, with various results, none of which were good.
Kohler, out of caution and warranty repairs, issued a service bulletin to pin the plug to the case with a small roll pin, so they would not move, if oil leakage appeared at the gov. plug area.--------- a easily preformed fix.
if the plug has remained all these years, it ain't going anywhere now.
Like a lot of problems reported of manufactured goods, one only hears of the ones that failed, not all the ones that preformed as expected.