Retorque head bolts M18

[Club Cadet]

I recently finished a top end overhaul on the Kohler M18 twin cylinder in my 1810.

New rings, honed cylinders, lapped valves, flattened heads, new oil lines, with all new Kohler gaskets. I did not split the case. I followed the Kohler service manual and everything turned out very well.

Some of Kohlers other engines call for the engine to be run and then the head bolts to be re torqued, but not the M18 (at least from what I could find). I curious as to why? I will say it would be very difficult on the twin to do this cause of the engine tin and oil lines that are blocking access to the head bolts.

[West Valley G]

I think it is a good idea to re-torque. And you are correct it's a bit of a
pain. I did one a while back and put the engine back in the frame without
the tins and only a couple mounting bolts. Ran it through a couple heat
cycles, pulled the engine and re-tourqued. Put all the tins back on and
then re installed engine. I found that the torque had not changed as much
as other Kohlers I have done. But I guess its good piece of mind. Plus you
get quite fast at pulling and reinstalling the engine.

Ken

[Club Cadet]

You did it the smart way.

Im 100% buttoned up bolted tight. I just can’t figure what’s different about the magnums when it comes to this issue.

[ol'George]

Do it now, or later, when they need replaced because you didn't retorque them.
Many years ago I thought I could get by with just overtightening them a few extra pounds.
It worked well for a few mowing's maybe 10-15 hours, then I heard it "whistling" so I replaced the whistler, and thought I'd check the other head.
When I felt how loose those head bolts were, I replaced it also and when the head came off, it too showed signs of leaking, it just didn't get to the "whistling" stage yet.
I still remember Clint Eastwood saying "Do you feel lucky punk?

[Club Cadet]

Well I torn the engine back out and went over the head bolts. They all turned a bit before the torque wrench clicked. Maybe 20 - 30 degrees of rotation +/-. There is about 10 hours on the engine at this point. Took me about 4 hours.

So I guess Im in the retorque club now too. Something to consider when putting one of these twins together.

[1711Cub]

While I love the smooth torquey operation from these, they do have some quirks, such as the gov. gear , the ever loving thirst for gasoline, and the head retorque. I do like the separate jugs. It makes it easy to work on and replace if they do wear out or become damaged. I just wished they had used the more robust iron gov. gear from the K series singles, and pinned the shaft from the factory.

[Club Cadet]

Yes, I suppose its a compromise just like everything else on this planet. If you want the power and smooth operation of a twin then you will burn more fuel and have to put up with the quirks from that setup. I had a 12HP K301 before this in a 1210 and it had good power but nothing like this twin. The twin is much smoother and more quiet than the 12HP was.

The M18 had 1000 hours on it when it became mine and from what I can tell the internals had never been touched and it still ran great. That's 35 years of service so even if the M18 has some weak links internally they are still very strong.

The separate jugs are cool. I used to own a air-cooled VW beetle and I couldn't help but notice the similarities between the M18 and 1600cc VW engine. Horizontally opposed, separate jugs, split engine case....

[West Valley G]

I would think that is 4 hours well spent. Now a person can just enjoy
using the tractor instead of wondering it the head is leaking.
I love the M18, but come to think of it I kinda love the 301 and all other
stuff that gets torn into around here.

Ken