DarZeelon

Quote:

ORIGINAL: togatoga

...[Thinner] literally leeches out any oil it is in contact with including the pores of the brass bushing. It also causes damage to any plastic it is in contact with.

Your engine was literally starved of oil as castor even though a very good lubricant is rather viscous and would need some time to work in while metal to metal contact was progressively destroying the con-rod especially running at high RPM. I suspect the lubricating hole and micro pores may have been inadvertently plugged up by a mixture of varnish and gunk dissolved and hardened by thinner.

Togatoga,


The bushing bearings in the con-rod are sintered bronze, rather than brass.

You are right about the theory... However, lubricant that has been absorbed into the all the cracks in the bronze is not a participant in the lubrication process, as long as sufficient oil is present on the surfaces. It is only in borderline lubrication conditions, such as the shaft bearings of an electric motor, that the lubricant lodged there will ooze out and provide surface lubrication.

In the presence of available lubrication, the total lack of oil within the sintered bronze, will not cause metal-to-metal contact...


...And the clean appearance of the crank-pin does not hint that the big end bearing has been spun.

togatoga

My Feedback: (42)

Thanks Dar, I stand corrected, it certainly is bronze.I was painfully misled by the OS rep. cum moderator in a moment of weakness in his earlier post! Nevertheless,the use of thinner solvent was the contributory factor in the demise of the engine. I've used paint thinner before in my younger days and they do make a mess of the engine by redepositing hardened gunk in the wrong places much to my chagrin!
I'm not well versed in metallury so I will not venture there,but i do understand that if there's no oil, there'll be scrubbing hence the presence of the hole in the conrod for oil lubrication.

DarZeelon

Togatoga,


I have no doubt no sliding joint will live for very long without lubrication...

Once you choke and turn the engine over to prime it, sufficient lubrication gets into the con-rod's lower end, for the engine to be started safely.


Regarding the redeposited debris, plugging lube-holes... You are correct!