Break-in

FreeBeeTony

Captain
Joined
May 15, 2002
Messages
3,991
Plan on splashing my rebuild this w/e.....
Last time I broke-in an engine I ran it 20hrs @ varying RPM's then changed the oil.
What is the consensus now?
Thought about making sure it's fully warmed and running it like I stole it!!

Any thoughts?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,297
guessing you have a flat tappet cam, so 20 minutes at 2000 RPM to break in the cam. then from there, varying loads for the first 20 hours, then run it like a rental.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Ayuh,..... I like atleast 10 hours under heavy load, varyin' throttle,..... lookin' things over, Often,....

Then run it like it's Yer's,.......
 

FreeBeeTony

Captain
Joined
May 15, 2002
Messages
3,991
FYI............it's a roller cam.
Not sure if I can wait 10hrs to test the cam!!......:rolleyes:
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
FYI............it's a roller cam.
Not sure if I can wait 10hrs to test the cam!!......:rolleyes:

The most important things on break-in are flat-tappet cams and breaking in rings! Since you have a roller cam, there's nothing to break in but the rings.

Hi power settings/heavy loads break in rings! So I'd run it like I stole it!!

Watch the temps and look for leaks! I would even take my IR temp "gun" and check the stat housing and risers frequently just to know the cooling water is going where it should
 

FreeBeeTony

Captain
Joined
May 15, 2002
Messages
3,991
Update: have about 6hrs on it...........most of it running ~3000-4000RPM's.
Checked the oil yesterday........seems to be a qt low.
Is this normal during break-in. Plan on running another 5-6hrs and changing it.
Going to use synthetic. I usually use conventional 20W-50, haven't seen anything this heavy in synthetic........

Don't want to post another thread on oil suggestions!
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Ayuh,.... All the boats I take care of are runnin' Rotella T, 15W-40,.... includin' my own barge,....

Glad to hear it's runnin' Good,.....

Are the fish bitin',..?? :)
 

FreeBeeTony

Captain
Joined
May 15, 2002
Messages
3,991
Hi Bondo.........

Yes, seems to be running good......curious to see what my WOT will be. Would like to go up in pitch if I can to get more speed!
Is my oil consumption normal?
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Hi Bondo.........

Yes, seems to be running good......curious to see what my WOT will be. Would like to go up in pitch if I can to get more speed!
Is my oil consumption normal?

It appears that your rings have not broken in yet. I probably wouldn't run any 50wt oil either. (great for aircooled aircraft engines though)

15W40, 25W40, straight 40 or even straight 30 (or 10w-30 syn) (IMHO) would be just fine....
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Oil consumption during run in is normal and to be expected. ...
 

FreeBeeTony

Captain
Joined
May 15, 2002
Messages
3,991
Thanks Mike..........I learned that today.
Why do you use the conventional?
Think I may try the blend.
 

Scott06

Vice Admiral
Joined
Apr 20, 2014
Messages
5,542
Conventional is less expensive and I don't put enough hours on the boat between oil changes to take advantage of synthetic. A gallon of Rotella at Walmart is the best deal going in oil
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Thanks Mike..........I learned that today.
Why do you use the conventional?
Think I may try the blend.

Particularly for run-in, use conventional oil, without friction modifiers.

Chris.....
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,800
Also if you can get at it, take an IR temp gun reading of the temp of your oil filter after running on plane. If you have high oil temps then after break in there may be some advantage of using syn due to the superior high temp characteristics of it vs conventional. Which brings up a question, what is normal oil temp on these engines? I'm thinking it should be at least 180-200 to burn off contaminates and fuel dilution but not more than 250* I'd guess....thoughts?

BTW before switching to the Merc conventional 25/40 I used both straight 30 and 40 with no problems in starting as cold as 45 * F. So the straight weights are still a viable alternative, given the narrow air temp range for marine engines, unless you are fishing in the winter. Personally I'd like to see a direct comparison between the Merc 25/40 and the Rotella/Delo/Pennzoil 15w/40 to see if there is really any benefit to the slightly more expensive Merc stuff.

and as far as I know, the only ones that do not use friction modifiers, are the straight weights and the Merc 25/40.
 
Last edited:

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,023
Conventional is less expensive and I don't put enough hours on the boat between oil changes to take advantage of synthetic. A gallon of Rotella at Walmart is the best deal going in oil

^^^this. If I upgrade to a newer engine, I'll probably switch to a standard synthetic.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
I would do straight 30 for breakin 20 hrs or so and then switch to your preferred secret sauce
 
Top