Break in procedure

[bcguy]

I have a new Isuzu 54 hp 4 cyl LE 1. My boat is 36' 12 tons steel sailboat. Shaft is 1.25 inches. The manual provided with the engine is for the "engine" nothing is mentioned in the manual about the engine ultimate use (example a boat). For break in they state (Jananese Translation) about not harsh treatment for 100 hours. If anyone has this engine could you please suggest some break in procedures.

... thanks

[bruce smith]

In general, keep the load below two thirds, vary the rpm occasionally, change the oil after 100 hours.

[Hud3]

Also, check valve clearances and adjust if necessary, and re-torque the head bolts to specs. It would be a good idea to change the transmission oil, too.

[Dennis.G]

Also, no excessive idling. Take it easy, but don't baby it - you want to get up to normal operating temperature.

[rtbates]

what the others have said is 100% correct.

I can only add that the most important thing to breaking in any engine is to VARY the load/throttle position/rpms as much as possible.

good luck

[Jim Cate]

Originally Posted by rtbates

what the others have said is 100% correct.

I can only add that the most important thing to breaking in any engine is to VARY the load/throttle position/rpms as much as possible.

good luck

I agree that the advice given agrees with common practice.

And Randy, I know that the "vary the load and speed" bit is conventional wisdom, but I have never heard WHY it should be so. Not overstressing, overspeeding, overheating or overloading is a no brainer, but why is this varying speed, etc, required?

Can anyone supply factual knowledge explaining this advice?

Cheers,

Jim

[bruce smith]

I dunno about factual, but uncle told me,
There is a lot of brand new metal down there , it will have more wear in the first 10 hours than the next 1000.
So, rings wearing into the cylinder liners, valve stems wearing into guides, not to mention the valve seating them selves. Oh, mains, and rods.
Varying the revs will move these things, molecules at a time. Thus , that early oil change.

[Ex-Calif]

Originally Posted by bcguy

I have a new Isuzu 54 hp 4 cyl LE 1. My boat is 36' 12 tons steel sailboat. Shaft is 1.25 inches. The manual provided with the engine is for the "engine" nothing is mentioned in the manual about the engine ultimate use (example a boat). For break in they state (Jananese Translation) about not harsh treatment for 100 hours. If anyone has this engine could you please suggest some break in procedures.

... thanks

In 30 plus years as a mechanic I have heard everything. I have overhauled aircraft engines and car engines. I have heard, run mineral oi, run it at full throttle, vary the speed, etc. etc. etc.

Mostly old wives tales. I would follow the manufacturer recommendation of no harsh treatment.

To me that means no WOT for 100 hours, no throttle "bursts", no towing, no "short" operations such as just in and out of the marina (get the temps stablized) and no long idling periods. 100 hours is a long time in a boat. I would set up some motor sailing trips, set the throttle at about 75% and get as many of the 100 in as possible.

After that I agree with others to change oil and filters.

[GRIT]

+1 to Ex-Calif

Paul.

[Jim Cate]

Originally Posted by bruce smith

I dunno about factual, but uncle told me,
There is a lot of brand new metal down there , it will have more wear in the first 10 hours than the next 1000.
So, rings wearing into the cylinder liners, valve stems wearing into guides, not to mention the valve seating them selves. Oh, mains, and rods.
Varying the revs will move these things, molecules at a time. Thus , that early oil change.

Bruce, this is exactly the kind of "information" that I was referring to!

Yes, there is some wearing in of new parts and abusing the engine, or even using it up to max ratings may exacerbate the wear, but why does VARYING the RPM change that situation, and why is it better for the engine?

An inquiring mind wants to know! (And tends to agree with the above posts that hint at old wives tales).

Cheers,

Jim

[Tellie]

At times, I've found some of those old wives are married to old diesel mechanics.

[Ex-Calif]

Originally Posted by Jim Cate

Bruce, this is exactly the kind of "information" that I was referring to!

Yes, there is some wearing in of new parts and abusing the engine, or even using it up to max ratings may exacerbate the wear, but why does VARYING the RPM change that situation, and why is it better for the engine?

An inquiring mind wants to know! (And tends to agree with the above posts that hint at old wives tales).

Cheers,

Jim

The idea of varying the throttle was related to something called glazing.

When a cylinder is new it is usually honed with a stone. Honing set up very small cross hatching in the cylinder walls. Depending on who or what you believe the "rough" surface of the cylinder wall interacted with the rings and over 100 hours or so the rings and cylinder wall cut into each other in perfect harmony for a perfect seal.

It is said that running the engine at a constant speed causes oil on the cylinder wall to glaze into the tiny honing grooves. This made the cylinder wall too smooth, the cutting/seating of the rings did not occur and high oil consumption would result because the rings did not seat.

There are different materials for rings and cylinders and oil is different than it used to be, You can second guess your manufacturer and vary your throttle throughout break in. I personlly don't think you will harm anything but why go contrary to the manufacturer recommendation? He is offering a warranty that is partly based on the break in instructions.

[Wotname]

Originally Posted by Jim Cate

I agree that the advice given agrees with common practice.

And Randy, I know that the "vary the load and speed" bit is conventional wisdom, but I have never heard WHY it should be so. Not overstressing, overspeeding, overheating or overloading is a no brainer, but why is this varying speed, etc, required?

Can anyone supply factual knowledge explaining this advice?

Cheers,

Jim

No to factual knowledge but of course I have an opinion and this is as good as any place to sprout it!

Best guess is that by recommending VARYING the rpm, one covers all bases. Even an idiot should know what that means and if he does it, the engine shouldn't be subjected to prolonged "harsh treatment".

Having said that, I know as soon as one makes an item idiot proof, an improved idiot comes along to break it.

Another "wife tale" - Run it in the same way as you intend to use it.