Post overhaul

[Bruce53]

Just completed a rebuild of a Stingray 195 SS Mercruiser 140 hp GM engine. Rebore, all new pistons, valve job, new bearings throughout, new manifold. I have run it at idle for about thirty minutes and plan to put it in the water next week. Question: what is the general agreement on breaking in a rebuilt engine? RPM, duration, etc.... Thanks.
Bruce

 

[Reel Poor]

Re: Post overhaul

Just take it easy on it for the first 20 hours. Dont' run full throttle till you have about ten hours on it and then only for short burst. Dont set the throttle and just let it cruise, vary the rpm's up and down a few hundred rpm's. Be sure to check the oil often as new motors may burn more oil than they will once they have been broken in. I would recommend changing oil and filter at the 20 hour period and also recheck the engine alignment. Good luck. 8)

 

[Haut Medoc]

Re: Post overhaul

Just take it easy on it for the first 20 hours. Dont' run full throttle till you have about ten hours on it and then only for short burst. Dont set the throttle and just let it cruise, vary the rpm's up and down a few hundred rpm's. Be sure to check the oil often as new motors may burn more oil than they will once they have been broken in. I would recommend changing oil and filter at the 20 hour period and also recheck the engine alignment. Good luck. 8)

Post up some hotties you slacker! ....JK

 

[bjcsc]

Re: Post overhaul

This topic is nearly as controversial as "what brand of oil" threads. I won't get into it, and the only thing I would add to RP's advice is many sources suggest not using synthetic oil during the break-in period. Remember, it's all about the rings. You have to get the ring surfaces to wear to the cylinder walls and seal before the cross-hatching on the cylinder walls wears off. Avoid running it without a load, you need pressure.

 

[f_inscreenname]

Re: Post overhaul

Ya, I have herd the same thing about synthetic. I will use SEA 30 to start and then move over to synthetic later.

 

[whywhyzed]

Re: Post overhaul

Whoever did the honing would be the one to ask about break in. Different hones (plateau, diamondhatch etc...) require different scenarios to seat the rings the best.
Use the lowest quality oil you can find for the first 25 hours. I would pull the filter after the first hour and cut it open with a proper filter cutter.
http://www.wesmarracing.com/images/catalo79.jpg

 

[Fishermark]

Re: Post overhaul

I have run it at idle for about thirty minutes

For what it is worth, if you installed a new cam and lifters, it is recommended NOT to let it idle upon start up, but to keep the RPMs up (If memory serves me correctly around 2,000 rpm or so) for the first 30 - 45 minutes. It helps the cam and lifters wear in properly, or something like that. Too late for you, but it may be helpful for someone else. :/

 

[Bruce53]

Re: Post overhaul

Many thanks guys.... Lots of good advice here it seems.......
Bruce