New Engine Break in

New motor break in – a simple process?

Well in reality, yes it is. Motor break in is actually the process of making sure all of the engines many parts are in place and ensuring each individual engine
component is properly interacting with its neighboring component. In this article, we’ll look at the how’s, why’s, and when’s of engine break ins. To begin, we’ll
consider the reasons why new engine break ins are necessary.

In applications using any sort of flat tappet camshaft (solid, hydraulic, or mushroom lifters), break in is needed to “establish rotation” of the lifter. The engine break
in period allows the cam lobes and the lifters to begin establishing their own unique and individual wear patterns. A flat tappet camshaft is ground with a very slight
angle to the lobes, and one of the reasons for this angle is to cause the lifter to rotate slightly within its bore on each stroke. Over time, this rotation will create a
wear pattern at the lifter/cam interface that is unique to that lobe-lifter pair . Consequently, this is why whenever lifters are removed and reused, extreme diligence
must be practiced to ensure each lifter is paired up with its original camshaft lobe. Mismatching a lifter with an established wear pattern to a different camshaft lobe
brings with it substantial risk of damaging both the cam and the lifter, and possibly ruining the entire engine!

Another reason for new motor break in is to begin the ring seating process. Similar to the lifters, over time, each piston ring develops it own one-of-a-kind seal with
its engine cylinder wall. Properly establishing this seal at the engine’s “birth” (or “re-birth” in the case of a freshening or rebuild) is vital to the engine’s performance,
as it will affect power, fuel efficiency, emissions and longevity.

As we move to the “how” chapter of the engine break in book, procedures vary as widely as the authors doing the writing. Ask ten different engine builders and you
will get ten different procedures. Whatever the precise procedure, it is important to follow YOUR engine builder’s recommendations exactly. Each engine shop uses
a procedure it has developed and refined based on years of experience that is individualized to that shop’s techniques and tendencies. For the purposes of this
article, we will focus on the procedure developed here at Mora Motorworks. This same procedure is printed on the cam card that comes with every Mora Motorworks
engine build.

1) Fill crankcase with Rotella 15w40 diesel engine oil to recommended
2) Add one pint of STP engine oil additive.
3) Use only a Napa Gold or WIX brand oil filter.
4) Make sure coolant level is full, and timing close to correct for your
5) Fire engine and immediately bring engine RPM up to 2000.
6) Keep at 2000 RPM for a minimum of 10 minutes.
7) Closely monitor the water temperature to ensure the engine does not overheat.
If the water temperature reaches 240 ºF, shut down and rectify the cooling system issue before continuing.
8) Monitor the oil pressure. It should never drop below 30 psi during break in.
If oil pressure drops below this, shut down, check oil level and determine pressure
problem before continuing break in.
9) After 10 minutes at 2000 RPM, increase the engine speed to 2500 RPM for one minute, then back down to 2000 RPM for one minute. Continue doing this for 15
more minutes.
10) After the initial 25 minute run in, shut the engine down.
11) Allow the engine to cool for a full 24 hours before firing again. Do nothing with the engine during the 24 hour cool down, this will allow the gaskets to seal and
give the new engine one complete heat cycle.

The reasoning for using certain procedures and products is something we’ve gained knowledge of after years of building and breaking in engines. We will not list
out all
of our reasons for this because we don’t want to freely give out secrets to everyone with an internet connection. If you’re really interested you can call or stop by
the shop and we can explain certain aspects of our procedure in greater detail.

Finally, we come to the “when” part of the equation. The procedure outlined above is based on flat tappet style engines. If you’re using a roller cam you need not
worry about a break in procedure this precise. In a rebuild application where you’re reusing a flat tappet cam, you don’t need to worry about the cam break in either.

However, if you’re using new lifters on a used flat tappet cam, or installing a new cam, you will need to properly break in the motor. The same thing goes for a
simple rebuild in which just the piston rings have been replaced and the block has been honed; you should use the procedure above to properly seat the rings.

On a fresh build with a roller cam, you just need to worry about your rings and gaskets, not cam and lifters. Again, this is Mora Motorworks’ recommended
procedure and others WILL vary. Check with your engine builder for their recommendations so as to not void any warranty you may have with your new motor. If
anything is in question, cam type, the type of rebuild done, etc., call your engine builder and they MUST be able to tell you.

We hope you have found this article on engine break ins helpful and informative. If you have any questions or would like further clarification, please feel free to call
or stop by the shop. And periodically check out the website for future Mora Motorworks technical articles.

For More Information Contact:

Mora Motorworks
2184 Prokosch Road, Mora, MN 55051
Tel: 320-225-0075
Send mail to with questions or comments about this web site.
Copyright © 2011 Mora Motorworks