What do you think?

[bsh21wash]

I get my boat back with a new long block installed ( 4.3 OMC Cobra) I talk to the guy at the shop and ask him if he has a break in procedure. I know I have already got advice from you guys, but I was curious on what these guys thought. I told him about the running it for 20 min with no load to break in the cam. He said they already did that. So I say so then what should I do? He says just run it as hard as you can, the harder the better. Now this didnt sound right to me. I know they didnt have it out on the water. So basically what I'm asking is there a chance that the motor is already broke in? I took it out yesterday and ran it for 10 min varrying the RPMS and let it idle for 3 min and did that for about 3 hours.

 

[WAVENBYE2]

Re: What do you think?

How did she do?

 

[bsh21wash]

Re: What do you think?

Did fine... I felt a little vibration at about 2500 RPMS but other than that good. I was just babying it, not trying to over load it.

 

[Modified]

Re: What do you think?

Yeah, I don't know about running the motor hard from the get go. I've always run mine in the yard with water for a couple hours a day for a week before putting it on the water. But that's just me.

 

[HT32BSX115]

Re: What do you think?

Running the engine for a short period of time for cam break in is correct.

It's VERY critical to break in the cam correctly or you'll have a flat cam in short order.

Running it hard after that is actually a good thing for ring break in.

It keeps the cyl pressures up so the rings seat well.

Don't baby it.


Regards,

Rick

 

[Coors]

Re: What do you think?

Keep the rpm/load varied. No constant load. Slow and let it idle a lot, so the temp changes. No wot until 10 hours, then only at 5 minutes. Change the oil at 10 hours. More wot at times until 20 hours. Change oil, and you are broke in. (OMC Factory Manual)

 

[Wide Open]

Re: What do you think?

Running the engine for a short period of time for cam break in is correct.

It's VERY critical to break in the cam correctly or you'll have a flat cam in short order.

Running it hard after that is actually a good thing for ring break in.

It keeps the cyl pressures up so the rings seat well.

Don't baby it.


Regards,

Rick

I agree. I am new to boating but know that you want all your rotating parts to seat themselves and stretch early in the engines life. I am not saying go out there and hold it wide open for hours on end but don't worry about running it up through the rpm range now that the cam is broken in.

 

[Robj]

Re: What do you think?

When breaking in a new engine, short accelerations loading the engine up is a good thing. It increases combustion pressure and helps seat the rings. I am not suggesting running it at WOT, rathering varying thr rpm,s and don't be afraid to put a load on it. Babying it is the worst thing for trying to seat your rings. This is even more important if they used chrome moly rings. Cast iron is not so bad to seat.

Have a great day,

Rob.

 

[bjcsc]

Re: What do you think?

Well, there are 2 schools of though on this. 1) Go Moderate 2) Go hard. One thing both agree on is that long periods of idling are bad.

The theory is to break the rings in before the crosshatch wears off of the cylinder walls. If you idle a lot, or don't run hard enough, the crosshatch wears down before it cuts the rings (which is why it's there).