I just have to share this with you. The wife let me buy a new boat last year in February. We decided on a Bayliner 242 with a 5.7 Mercruiser. It has burned oil ever since we started using it. We put about 150 hours on it since taking delivery. I finally convinced the dealer that it should be broken in and not still using oil. Long story short, #3 cylinder had no comprssion. The dealer pulled the head and the rings were shot along with the cylinder in general. Mercruiser is sending a new motor and it will be installed next week. The part I do not look forward to is breaking in a new motor again with the price of gas as high as it is. They want you to only drive it no faster than half speed for the first 20 hours. Is this reasonable or is there a faster way?
New Motor
- Thread starter herronjoe
- Start date
5
5-Salt Fever
Guest
No single event in a motor's life can better determin longevity than a proper break in. What ever they recommend - follow it to the letter and increase the time to 30-40hours total.
General rules for marine engine break in:
First ten hours:
-No trolling or extended idling
-Never more 50% rpm
-Never same rpm for more the couple of minutes.
-Varied RPM's are critical.
-Lighter fuel/pax/gear loads if at all possible
Next Twenty:
-No Trolling or extended idling
-Begin to operate at RPM over 50% but avoid 80% plus rpms for more than 2-3 minutes at a time.
-Never same RPM for more than 3-4 minutes at a time.
-Heavier crew/fuel/gear loads
After Thirty hours:
-Change oil
-Operate per normal factory recommeded RPM's and loads.
The only motor I ever had oil consumption problems with was the one I abandon break in procedures after 10hrs. It's painful and its temping but, stick with it for full 30hrs.
General rules for marine engine break in:
First ten hours:
-No trolling or extended idling
-Never more 50% rpm
-Never same rpm for more the couple of minutes.
-Varied RPM's are critical.
-Lighter fuel/pax/gear loads if at all possible
Next Twenty:
-No Trolling or extended idling
-Begin to operate at RPM over 50% but avoid 80% plus rpms for more than 2-3 minutes at a time.
-Never same RPM for more than 3-4 minutes at a time.
-Heavier crew/fuel/gear loads
After Thirty hours:
-Change oil
-Operate per normal factory recommeded RPM's and loads.
The only motor I ever had oil consumption problems with was the one I abandon break in procedures after 10hrs. It's painful and its temping but, stick with it for full 30hrs.
Little Hawk
Active Member
Howdy from Canada HJ!
I'm going through the break-in on my new Merc 4.3/MPI/Alpha. The unit was installed by a Merc mechanic here in Victoria.
You should have gotten a Merc owners manual with your new engine; if you didn't - get one, and read it.
My mechanic's advise more or less mirrors the break-in advise in my manual with one notable exception - he recommends doing an oil change after the first 'ten-hours'.
"Why?" you ask.
He points out that during the break-in and up to the point that the new rings are fully seated (some oil consumption is normal here) that a considerable amount of fuel seeps past the rings and contaminates the oil. His contention is that an additional oil change during this period will only prolong your engine life.
Makes sense to me.
Merc manual says:
First 10/hours:
-do not idle below 1500 rpm.
-do not operate at consistent speed for extended periods.
-do not exceed 75% throttle. (in the case of my engine, that's about 3800/rpm)
Next 10-hours:
-operation at full-throttle permissable for no more than 5-minutes at a time.
After 20-hours, change oil.
Hope this helps.
Good luck with your new mill.
Cheers,
Terry
I'm going through the break-in on my new Merc 4.3/MPI/Alpha. The unit was installed by a Merc mechanic here in Victoria.
You should have gotten a Merc owners manual with your new engine; if you didn't - get one, and read it.
My mechanic's advise more or less mirrors the break-in advise in my manual with one notable exception - he recommends doing an oil change after the first 'ten-hours'.
"Why?" you ask.
He points out that during the break-in and up to the point that the new rings are fully seated (some oil consumption is normal here) that a considerable amount of fuel seeps past the rings and contaminates the oil. His contention is that an additional oil change during this period will only prolong your engine life.
Makes sense to me.
Merc manual says:
First 10/hours:
-do not idle below 1500 rpm.
-do not operate at consistent speed for extended periods.
-do not exceed 75% throttle. (in the case of my engine, that's about 3800/rpm)
Next 10-hours:
-operation at full-throttle permissable for no more than 5-minutes at a time.
After 20-hours, change oil.
Hope this helps.
Good luck with your new mill.
Cheers,
Terry
westcoast advneture
Member
Have to agree with what has been said. I a mechanic by trade and the only thing I would add is that after your break in keep up the oil changes maintainence etc. Marine engines are a special breed where you are basically asking your engine to work underload at all times with varying speeds and loads ie running through a chop. Marine horspower is a bit of a funny thing as it is not a true rating. It is measured at peak hp on a dyno for a short period of time. If you ran your engine at that it would pop in a short time. To put it in perspective a highway tractor trailer is generally about 425hp and pulling huge loads. My pickup is rated at 345 and would not even move a highway trailer. Another example would be a diesel generator that is always running at a constant speed and running only at 3/4 most of the time. It is not uncommon to see these engines with 25,000 hours on them before a major rebuild. Loosing one cylinder in your engine probably was not from lack of break in but a bad engine from the factory not to say that break in is not important. Every now and then every manufacturer has a dud come of the line. Lucky for you the dealer is going good for it.
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