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Run in period

B

burls

Contributing Member
As you know it getting close to testing.

l was pondering how long should the run in period Ben and what should l do or not do?

rev limits?

load limits?

Skiing or tubing maybe or not?

how long at idle?

that sort of thing
 
Ayuh,..... Whatcha workin' on,..??

A flat tappet cam break-in is different than a roller tappet cam,.....
 
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burls said:
As you know it getting close to testing.

l was pondering how long should the run in period Ben and what should l do or not do?
The OEM would very likely recommend something in the range of 10 hours of variable Run-In speeds and variable loads!
See the OEM recommendation.


rev limits?
Yes.... limit RPM but DO NOT prevent the engine from reaching moderate RPM for short periods.
Again..... see the OEM recommendation.

load limits?
Yes.... limit loading!

DO NOT attempt break-in/run-in unless you know that the gear reduction and propeller selection will allow this engine to reach the OEM specified WOT RPM.

Also, the hull must be clean, the prop must be in good tune and you must be using the correct over-all gear reduction!
If any of these are incorrect, you will risk over-burdening this engine at any RPM.
You DO NOT want to over-burden this new Engine..... and in particular during the break-in/run-in period.



Skiing or tubing maybe or not?
NO!

how long at idle?
With roller cam followers there is no real run-in time to speak of ...... however, your cylinders/piston rings are splash lubricated.
Personally, I would avoid operating at idle speeds for any duration until after the break-in.



Bottom line:
Crankshaft bearings, connecting rod bearings, camshaft bearings and roller cam followers do not really require run-in.
Piston skirts, cylinder walls and piston rings do.
We want to load the engine in order to create pressure behind the piston rings so that in turn "seating" occurs.

At the same time, we do not want to over-pressure the cylinders, and/or much worse........ over-pressure the cylinders for any long durations.
Click to expand...





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Last edited:
Thank, it was kind of what l thought but l haven't done a mercruiser before.

what oil should l use for the run in period?
 
I was recommended to use Rotella 15-40 diesel oil (non synthetic) for break in. Did the same vary rpm light loads for 10 hrs, not brief WOT until after 7 hrs, worked fine. Changed the oil after 1 HR and 10 hrs.

This was on a new base engine from Michigan Motorz, was surprised they recommended diesel oil, said it drops out particulates. Best parts is its $13/ gal at Walmart. Bottom line engine runs great.
 
Slightly off topic...... but when adjusting your cam follower plunger depth (what some call adjusting valves), be certain to use the 8 stop procedure.... not the 2 or 3 stop.

Begin with #1 cylinder at TDC C/S (must be on Comp Stroke).
Adjust both intake and exhaust cam follower plungers by finding ZERO lash and then using the OEM suggested additional fraction of one adjusting nut rotation.

Roll crankshaft 90* and adjust same for #8 cylinder.

Keep going right down the firing order until you're back to #1.

If your cam and followers are new, make this adjustment before you prime the oiling system.



This GIF demonstrates the plunger's function.

https://www.youtube.com/watch?v=lorANZ1Tptw


I have been using the 8 stop for well over 45 years. It is much more accurate, and if done correctly you will not need to go back through them dynamically.


 
Thanks Ricardo
I found a lot of conflicting information here but finally did it via the method you discribed
 
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