Proper break in of rebuilt Cub 149 motor
 

Gentlemen!

I've just had a Cub 149 motor rebuilt. I had the piston, rod, rings, governor gear, and gaskets replaced with all genuine Kohler parts. What are some tips for breaking in the motor properly and what things should I avoid like the plagued? Also, I've heard from one source not to run the motor wide open for awhile and from someone else that it is supposed to be run wide open. Because I've been without it for a year, I was anxious to cut with it, and I did cut some pretty thick grass for about an hour and a half at about 60 percent throttle. Also how soon should I change the oil? And does anyone recommend synthetic Lucas oil additive to prevent dry starts? Also I was told that there were some sort of 'bushings' or something in the motor that helps with vibrations...that should've taken out at the the time of the rebuild and I'm not sure that they were. Will these "grenades" go off unexpectedly in the future? I wish I had consulted with you experts before I ran the 149 at all, and hopefully no harm done... but I'm sure your advice can greatly benefit me from this day forward. Thanks for your help and expertise, and any other related tips are greatly appreciated.

Dan
"RebuildK321"

the counter balance gears should have been taken out because they are granades.

Well since you have already run it, it's time to retorque the head bolts following the Kohler manual specs. I plan to hook up a sled and load it with big field stone and pull my rebuilt 128 WOT to work the governor real good after I retorque the head.
Working the engine like you did at partial throttle while mowing is hard on the motor and can cause overheating. These motors are designed to run WOT all the time, especially if you are working them. Hopefully you don't have the balance gears in the motor. Those are the items that have a tendency to let go and make an inspection window in the motor.

Change the oil now, after 5 hours, and per the manual interval after that. Do not use anything other than 30W non- synthetic oil until the rings seat. As has already been mentioned, never run the tractor under load at anything less than full throttle, or you will overheat it and take the temper out of the rings.

Just curious.....running an engine wide open throttle under load, is that for all of these cub engines or just rebuilt engines? Thanks...

Cub Cadet 123

For "ANY" air cooled motor, especially these big Kohlers. WOT always. :beerchug: Your service manual and I think your owner's manual should tell you this also.

I used to rebuild several Kohlers every year ( no extra time now). The procedure I use is to vary the RPMs from idle to wide open for the first 45 minutes. I never leave a motor run very long at the same RPM. If the motor is in a Cub Cadet I will drive it after the first 10 minutes of running. After the 45 minutes run time I will drain the oil and refill it with fresh oil.

I will put a load on the motor/Cub Cadet for the next 2-3 hours. The load can be a weighted sled, moldboard plow or anything that works the motor. The RPMs are varried during the 2-3 hours pulling the load. I will vary the RPMs during the 2-3 hour load session. The oil is drained and replaced, head bolts are retorqued and valve lash is check and adjusted as needed.

The reason for varing the RPMs is to help to break in the rings. Different RPMs put different loads on rings.

The oil I use is Kohler brand dino oil. I used straight 30 above 32 degrees and 10W-30 when temps are below 32 degrees. I see no gain using synthic oil.

The majority of the time my Kohlers are run at wide open throttle. Depending on the task (cultivating, pulling trailers and spraying ) I only run motor 1/2 to 2/3 throttle. Hard uses such as mowing and plowing the motor is run at wide open throttle. Keep in mind wide open throttle is more than the Kohler spec.

The oil is change again after 5 hours of run time. After that the oil is change every 25 hours.

I haven't had any motor failures breaking in a new rebuild using this method.

Does the K241 have these balance gears in them? Should they be taken out?

Does this break-in process need to occur on one that was just re-ringed only?

Did you just replace the rings?
What where the cylinder bore measurements before rings were installed?
Was cylinder honed before new rings were installed?
What were the cylinder bore measurements after the cylinder was honed?

Did you measure the cylinder bore in 6 places per Kohler manual?