Proper Break-In Procedures

[thirtydaZe]

I'm sure it's been discussed to death around here, but not being able to readily find the topic in the search I thought I'd ask.

What break-in procedures are preferred? Seems everyone's method is different, and I'm equally sure that when I'm able to get my hands on the manual that will tell me something too.

At any rate, the engine in question is a 350 mag. BIII if that matters.

 

[avguy]

I think the main thing is to not run at a constant speed/RPM for any length of time. I also didn't run at WOT until I had (I think) 20 hrs or so on the engine.

 

[Tonka Boater]

Here you go:

MerCruiser Engine Break-In Procedure:

Note: Perform the break-in procedure any time internal components of the engine are replaced. During the first few hours of running, many of the engine components must avoid full load until fully seated. Failure to properly break in the engine can result in engine failure, decreased performance, short engine life and increased oil consumption. An engine needs approximately 20 hours of running time to be fully broken in. Increased oil consumption can be expected during this period. Check the oil frequently during break-in.

1. Check the tightness of all external fasteners during the break-in period.
2. During the first 5 hours of the break-in period, DO NOT exceed 3500 rpm OR half throttle. Do not run on any given throttle setting for more than a few minutes.
3. During the second 5 hours of operation, advance the engine to full throttle for 2 minutes or less. Otherwise run the engine at 3/4 throttle (3500 rpm) or less during the second 5 hours.
4. During the final 10 hours, operate the engine at full throttle for a maximum of two minutes at a time. Otherwise run the engine at any throttle settings below full throttle.



Break-In Procedures for MerCruiser Sterndrives

1. Make certain the drive is filled to its maximum level with the appropriate gear lubricant.
2. Make certain that all bolts and screws are tightened according to factory installation specifications.
3. To ensure a balanced break-in, engage the reverse gear approximately 25-30 times during the first 10-hours of drive operation.
4. DO NOT gradually engage into gear. Grinding the gears will result in premature gear failures.
5. DO NOT perform full-throttle starts.
6. DO NOT operate at one constant speed for prolonged periods for the first 10-20 hours of drive operation.
7. DO NOT exceed 75% of full throttle during the first 5-hours. After the first 5 hours it is acceptable to operate at full throttle intermittently.
8. Clean the drive and transom assembly after each use to reduce the potential for corrosion. Especially in salt or brackish water.

 

[BonBini]

One very important thing that I don't see in the Merc. recomendations is. Let engine warm up good before putting much of a load on it... You want that oil warm! Also ease into your intended load range. ie: get it up on plane quickly then back off, then ease your speed up to where you want to run. Best of luck with your new boat. ...Ron

 

[thirtydaZe]

Thanks guys, great read.

 

[sbw1]

For what it's worth, Crusader pretty much recommends the Merc approach for its 8.1s. The WOT is critical to seating the rings and avoiding oil use after break in. This topic suggests there are various approaches. The only way to do it in my view is per the owner manual for your specific engine.

 

[Tonka Boater]

The only way to do it in my view is per the owner manual for your specific engine.

Agreed. The above procedures are for the 5.7 - 8.1 and BIII....I should have mentioned that.