Stupid question?

I had an idea for engine break-in and thought I would ask if it might work. The idea is to mount a new engine on a device that is capable of turning the engine at normal speeds and drip the appropriate lubricant (at required intervals) into the glow plug hole. After a determined amount of time would this break an engine in?

You need heat and pressure to get the engine broken in. If it has rings, they won't seat without that pressure; they'll instead glaze themselves and the cylinder wall and leak forever after. The engine needs to be run.

Dan

Needs to be run. mk

On ABC or ABN engines the cylinder sleeve is designed to account for expansion in the presence of combustion heat in the upper part of the bore (the so-called "tapered bore"). And the piston is designed for optimal fit at operating temperature. Your scheme takes combustion heat out of the equation. I suspect only bad things could happen...

/daytripper

Thanks for the input guys. Heat/compression didn't even cross my old fart mind. AND another thing is setting mixture etc.

On Thu, 23 Nov 2006 08:45:55 GMT, "Mark Daughtry, SR" wrote in :

It was an interesting question and it elicited some interesting answers. Way to go, Mark!

Marty

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I also wonder how heat cycling in the metals may be involved.

Some metals have their characteristics change, quite drastically, when going though cycles of heating and cooling, usually to the benefit of strength and hardness of the metal. I'm thinking this may be involved, also.

Absolutely. Stresses built up in casting and machining are relieved, so the combination of heat and well-lubricated friction are both critical to a good break in. Maybe a better term is "running in," a term that was once common, but seldom heard nowadays.

And remember, there are no stupid questions, just stupid answers! :-)

Geoff

That's a myth ;-)

I'd say no for several reasons:

1. That oil isn't "dripping" into a chamber thrashing around at 10000+RPM, it's being sucked and blown out via the exhaust and the glow plug hole. A lovely oily mess that replicates nothing the engine does when operating.

1. There is no combustion and thus no equivalent pressure levels,. heat, loads etc to replicate typical engine conditions. You're relying on bare friction of the cylinder and piston (modified by your mess of oil) as the sole means of running in the engine.

2. Explain how a typical two stroke engine using a ported crank is going to wear with no lubricants passing through the carb, shaft, crankcase, bearings and, schnurel (sp?) ports. Your method only lubes the upper cylinder and nothing else.

1. Your driving a load into the engine via the crank, which is backwards to how an engine normally runs (drive comes out the crank). Hence, you're not replicating how the engine really operates and thus not how it would typically run in.

The easiest and proven way of running in an engine is to actually run it, ideally according to what the manufacturer has found to work best for their engines.

You had an interesting idea, but I wouldn't use it.

Back in my U/C days it was not an uncommon practice to "motor" a Fox .35 in a drill press with light oil supplied to the venturi for 12 - 24 hours. Reduced the normal 5 gallon break-in to 1 or 2 gallons. There was also a product called lustre something that would supposedly accomplish the same thing but it was easy to over do. Alas this was a lapped iron piston & sleeve. I wouldn't recommend it with any other type engine.

You're thinking of Fox "Lustrox", which was a mildly abrasive powder that you mixed with castor and dabbed into the venturi of a running lapped piston engine.... Too much and you were in the market for a new piston and liner..........

Bill

Yep, That's the stuff. My LHS used to keep it behind the counter and give out stern warnings to anyone who would dare to use it. I never tried it. Lots of good memories have been brought to mind by this thread.

I watched two fellows use Lustrox to seat the ring in a large block Fox .45 BB engine. Guess what else they "seated"?

I warned them, but was not so politely told to mind my own business. So I didn't feel so bad when I couldn't stifle the laughter at the results of trashed bearings and a ruined crankcase/crankshaft fit.

Ed Cregger