View Full Version : Break in procedures for rebuilt engine

05-22-2012, 10:50 AM
New block, new heads, valves. Bearings were in good shape as were pistons. New rings etc.

What is the recommended break in time? My former partner in the boat broke it in last time and if I recall there were varying speeds and rpms and no loads until a certain time had passed. Maybe 5 hours, not sure.

I should be able to start break in on Friday.


05-22-2012, 02:04 PM
I would contact the engine builder and see what he recommends. Also find out what type of oil was put into the engine, as that will be a factor too.

05-22-2012, 04:05 PM
They put 15 40 in it. I just heard it run at the shop and should have it in the water on Thursday.

I'll look at my owners manual and see what it says for initial break in. The engine builder says varying speeds and rpms for the first 2-3 hours and no loads (skiers) until then as well.

From Indmar:

The three (3) most important aspects of new engine break-in
Avoid running engine at high speeds.

After the first 10 to 20 hours of operation, take your boat to
the dealer for its first oil and filter change

Do not carry a heavy load (passengers, gear, etc.).
Vary your boat speed during break-in.

Do not run at the same
RPM for a long period of time.

For the first hour, do not exceed 2,000 RPM.

For the second hour, do not exceed 3,000 RPM.

For the next five hours, do not exceed 4,000 RPM

Avoid fast accelerations and do not carry (or pull) a heavy
load during this period.

Always let engine warm up gradually before acceleration.
Check oil frequently.

During the first 50 to 100 hours, an
engine can use more oil than usual. Maintain oil at a proper
level at all times (do not overfill).

A little research goes a long way! ha

After the first 10 to 20 hours of operation change the oil.

Thanks for the reply, I'll report back after break in.

05-22-2012, 09:25 PM
Since they didn't add non detergent oil, you should just do as you have written up there.

05-25-2012, 04:31 PM
5 hours of break-in in the books, 2 more to go. No problems so far. Oil down less than half a quart. Topped it off. No leaks, all seems well.

Engine sounds a bit different than the old one. Can't wait to see how she jumps out of the hole.