After rebuild - running in

[sildene]

After the rebuild of my 3-cyl Bukh diesel, it has been suggested to me to use "Running-in Oil" for the first 50 hours.

Looking at the Pennzoil web site spec for Pennzoil Running-In Oil, it says "a non-fiction modified SAE 30 mono-grade motor oil designed for ‘running in’ of reconditioned motors".

My first question: since my manufacturer specifies a mono-grade 30 oil for general use of the engine, is there any point in considering a different "running-in" oil?

The rebuilt engine is currently in my garage while I make some cooling system changes. The engine is still quite stiff and the new rings have NOT been bedded in.
As we know, gasoline engines are loaded very lightly when running in.
But to run in the rebuilt diesel:

a) Should I run it in, in the garage under light/no load (and if so, at what rpm), or defer until installed in yacht loaded with prop?

b) I need to periodically run it in the garage while installing and testing my cooling system mods (probably minimum of one to two hours total) - any ideas on how to minimise ill effects of no-load, unbedded running?

Much appreciative of any comments or advice.

[Tom Spohn]

Some advice.
Universal Diesel Engine Owners Manual - Break In and General Running- Marine Diesel Direct / Torresen Sailing Site

[Alan Wheeler]

Running it is when in the boat is best. You do need it under a bit of load. However, you do not want too much load or too high revs, or you can over heat and maybe damage rings and in the worst scenario, seize.
You can run it in the garage OK. I suggest you have the Alternator connected and make it work on a good load, like some 12V lamps and a flattish battery or two or three. This will ensure the engine has some work while you test.
Any 30W running in diesel oil will be fine. Ensure you change the filter when you change the oil.

[Ex-Calif]

Originally Posted by sildene

Pennzoil Running-In Oil, it says "a non-fiction modified SAE 30 mono-grade motor oil designed for ‘running in’ of reconditioned motors".

Definitely use a non-fiction oil. Fictitious oil is hell on bearings.

[mudnut]

Originally Posted by Alan Wheeler

Running it is when in the boat is best. You do need it under a bit of load. However, you do not want too much load or too high revs, or you can over heat and maybe damage rings and in the worst scenario, seize.
You can run it in the garage OK. I suggest you have the Alternator connected and make it work on a good load, like some 12V lamps and a flattish battery or two or three. This will ensure the engine has some work while you test.
Any 30W running in diesel oil will be fine. Ensure you change the filter when you change the oil.

Hey Wheels,

This might sound like a dumb Q,but ,If the alt is allready hooked up,IE,belt conected,why would having batteries hooked up to charge put any more load on the motor anyway,since charging the battries is only a by-product of the alt's main function.Mudnut.

[seafox]

The power has to come from somewhere I suppose. I reckon my car engine works heaps harder when the wipers, lights and heater is going.

[mudnut]

Originally Posted by seafox

The power has to come from somewhere I suppose. I reckon my car engine works heaps harder when the wipers, lights and heater is going.

Seafox,

I carn't see how that happens.Example.1,take an engine with the alternator hooked up normal with a belt conected,but no wire's conected off the alt,idle motor,ex amount of load on motor.2,same as #1,but,with wire's conected to say a flat battery,idle motor.In both case's the belts were hooked up to the alternator,just because the alt is now putting out a current dosent put any more load on the motor.Is there something really technical happening here that I carn't see.Mudnut.

[rtbates]

Originally Posted by mudnut

Seafox,

I carn't see how that happens.Example.1,take an engine with the alternator hooked up normal with a belt conected,but no wire's conected off the alt,idle motor,ex amount of load on motor.2,same as #1,but,with wire's conected to say a flat battery,idle motor.In both case's the belts were hooked up to the alternator,just because the alt is now putting out a current dosent put any more load on the motor.Is there something really technical happening here that I carn't see.Mudnut.

Nothing too technical. Just the theory of electrical fields and magnetics. What you're missing is the knowledge of how electrical fields react to current flow. The 'power' required to drive any alt/gen is in direct proportion to the amount of current that it's required to deliver. You've never been around a big diesel gen set when the load is switched in? Or noticed that when the lights are turned on a car at idle the engine will react?

[sildene]

Mudnut, you should be able to demonstrate to yourself what Randy's saying by disconnecting your alternator belt from the engine and spinning it by hand. Compare the alternator's resistance when the battery is disconnected, versus when the battery is connected. You would 'feel' the electromagnetic field's considerable resistance.

[mudnut]

Ok,

The load is put on the alternator to produce the current,but surely not on the motor to TURN the alternator,as it would be doing this in any scenario.So are you saying that when the battery is fully charged up then the load on the motor decrease's,even though it is still spinning the alternator at the same rate,same tension on the belt it's self."Please explain" Sorry Pauline(pun intended)It's an Ozzy thing.Mudnut.

[sildene]

I think you're onto it with 'belt tension' - the moment the alternator needs to deliver (more) current to its load, it resists and the belt tension rises substantially (may even think about slipping). The engine may reduce rpm due to the additional load, unless the IP governor compensates by supplying more fuel.

Originally Posted by mudnut

Ok,

The load is put on the alternator to produce the current,but surely not on the motor to TURN the alternator,as it would be doing this in any scenario.So are you saying that when the battery is fully charged up then the load on the motor decrease's,even though it is still spinning the alternator at the same rate,same tension on the belt it's self."Please explain" Sorry Pauline(pun intended)It's an Ozzy thing.Mudnut.

[44'cruisingcat]

Originally Posted by mudnut

Ok,

The load is put on the alternator to produce the current,but surely not on the motor to TURN the alternator,as it would be doing this in any scenario.So are you saying that when the battery is fully charged up then the load on the motor decrease's,even though it is still spinning the alternator at the same rate,same tension on the belt it's self."Please explain" Sorry Pauline(pun intended)It's an Ozzy thing.Mudnut.

Unloaded, an alternator spins quite freely. It's harder to turn when it's working. The harder it's working (the more current it is producing) the harder it is to turn. Since the engine is the thing turning it, the more load on the alternator, the more load on the engine.

That's why you can't power a city with a big generator hooked up to a lawn mower engine.

[mudnut]

Originally Posted by 44'cruisingcat

Unloaded, an alternator spins quite freely. It's harder to turn when it's working. The harder it's working (the more current it is producing) the harder it is to turn. Since the engine is the thing turning it, the more load on the alternator, the more load on the engine.

That's why you can't power a city with a big generator hooked up to a lawn mower engine.

I just thought,"That could be a seperate problem",that since the shaft of the alternator was supported between two bearings and the magnetic thing-a-ma-jiggs never were in actual contact while spinning,that it should'nt cause anymore load to the motor just because it was sending current to,"What ever".I didn't realise there was that much resistance in making current.Is there some sort of percentage table to go with it all?Mudnut.

[Alan Wheeler]

Yep, work done is work done. If an alternator is producing 14V and a current of say 60A, then 14 x 60 = 840W. That's a little over 1 Hp.
Ever had one of those old dyno's on a bike tire. Swtich the light on and it damn near sends you to a stand still. That little light bulb is taking that much energy from your legs to illuminate it.

[mudnut]

Ok,I believe ya.
Still not sharp enough to know why,but I will work on it.Electrical ressistance= load,even though the two parts making the current are not touching each other.The bike light and dyno I can understand.Humor me a bit Wheels.If I had a switch inbetween the dyno and light,had the dyno on the wheel and the switch off,would turning the switch on increase the load to the pedals.Seeing that I was allready turning the dyno anyway.Mudnut.