Engine Break-in Procedure

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PTWannaHave
Posts: 295
Joined: Wed Apr 11, 2012 12:39 pm
First and Last Name: Ben Michaud
Location: Richmond, Ontario

Engine Break-in Procedure

Post by PTWannaHave »

Hi all,

I searched the forums quite a bit to find this info (that I'm pretty sure is here), without success. Should make a good How-To thread... I'm sure there is very useful collective experience out there to be added to what may have been printed in a manual...

In my case, I am getting ready to fire and break-in a total (stock) rebuild. Perhaps this thread can be split in two for 'total rebuild' and 'freshened'? (I.e.: If only connecting rod, piston and rings are changed, perhaps break-in procedure need not be as comprehensive...?) Might need a third section for non-stock (hopped-up) rebuilds?

Everyone seems to have their favourite oil recommendation, so I wasn't going to go there... (For the record, I am using Walmart SAE40 detergent-free oil.)

I seem to recall a procedure such as 'run 5mins while adjusting carb; change oil; re-torque head bolts; run 10mins fluctuating engine speed; change oil; run 10mins under load (driving around); re-torque head bolts'.

I torqued the head bolts to 25ft/lbs, and was planning to add 1-2 ft/lbs every time I re-torque... Bad idea? (Spec is 25-30ft/lbs.)

Thank-you in advance for your collective wisdom,
PTWannaHave

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Merk
Posts: 150
Joined: Mon Sep 06, 2010 9:24 am
First and Last Name: Dale Merkle
Location: Middle Point, Ohio 45863

Re: Engine Break-in Procedure

Post by Merk »

This is the way I break in a rebuilt engine ( Cub Cadets-Kohler engine).
I will vary the engine RPM for the first 25 to 30 minutes. I will leave the RPM at a the same speed for a minute. I will drain the engine oil and replace with new oil. The next 30 minutes I will drive the tractor around. The RPM will vary the same as the first 25 to 30 minutes. I will drain the engine oil and replace with new oil again. The next 3 to 5 hours I will put a load-work the engine. I will drain the engine oil and replace with new oil again. Them I will drive like a stole it......plow days are a good place to break in a rebuilt engine. I will retorque the head bolts around 25 hours run time at 30 ft/lbs. Break in procedure is the same for stock and modified engines.

Kohler manual says to use straight 30 weight oil with temps above 32 degrees and 10W-30 below 32 degrees. I use Kohler brand conventional oil. I'm not a fan of synthetic oil.
Kohler manual says to use a detergent oil.

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chzuck
Posts: 320
Joined: Tue Sep 07, 2010 2:51 pm
First and Last Name: Charlie Zuck
Location: Elizabethtown, PA

Re: Engine Break-in Procedure

Post by chzuck »

Engine break in is a little like brands of oil -there are lots of them. I have always used a 30 wight non-detergent for the first 5 hours after a rebuild. I use Rotella 15w40 in all of my air cooled engines year round. I am not a fan of synthetic oils either. I am not saying my method is better or right. Merk's method seems like a whole lot of extra work for me. I am sure it has given him good results. One thing to consider - the science of lubrication and additives has come a long way since our beloved K motors were first made. Rotella 15w40 is a heavy duty oil, great for the summer heat and with a multi-viscosity oil I can use it year round. You will have to read what all posters say and decide which you think is best.
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BigMike
Posts: 1296
Joined: Mon Sep 06, 2010 8:45 pm
First and Last Name: Mike Andrews
Location: Niles,Michigan

Re: Engine Break-in Procedure

Post by BigMike »

I have not done a scientific study of engine break in but it is very close to what Merk does. I feel that that the sooner you can flush the loose metal particles and assembly lube the better. Once that's done running under a good load will puts pressure and lots of oil on the rings and well seated rings = happy engine.
I have never run synthetic oil in my Cubs....just good ole Dino type :beer: . I figure they lasted 40+ yrs with conventional oil they will last the balance of my life.

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