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Listeroid Engines / So you think you've got no sand/dirt?
« on: September 03, 2006, 04:01:31 PM »
I pulled my bearing shells recently after 15 hours of break in on my Metro 6/1. I was running Delvac 1300 15W40 for break in hopes of catching more crud in my gravity filter. The break in was with a light load- a single 1/2hp submersible water pump. I will be switching to straight 40 weight. My Metro 6/1 has a small sump which does not allow settling.
This engine had a pretty clean sump on arrival, some crud but no signs of sand though the bearing shells were scratched from the factory test. (Shells replaced.) When I pulled the cylinder to have it planed and to hone it (it was not honed) I did poke and prod carefully inside the crankcase with dental picks and a mini spotlight and did not find any sand pockets or soft corners.
Bearing inspection at 15hrs of run time:
The lower shell was just slightly scratched, small particle type damage, with some pits where particles were embedded in the bearing. Without Hotater's advice to always check the upper shell, I might have stopped there thinking it didn't look too bad at all. There was no other sign of wear but the fairly minor scratch/pitting.
The upper shell has scratching and fine particles embedded near the oil holes, these scratches from the oil holes in the direction of rotation. There are also some significant, long scratches, and enough embedded (very fine) grit that putting them back in seems a bad idea. No other wear is evident.
So far, the crank isn't scratched up, the thick bearing material has done it's job.
I pulled my gravity oil filter box from below the breather door and pulled out all 7 bounty paper towels and the 100 tpi copper mesh screen at the bottom. The top two towels spread out showed a modest amount but wide variety of particles- some that might be fine sand, some fine metalic ones that look like brass, some clumps of soft gunk. The lower towels were clean but for the usual carbon soot. The screen just had paper fuzz and a few other specks of crud. The magnets in the filter box had very fine, soft metalic fuzz on each end. About the volume of two BB-s worth on each magnet.
I had previously changed the top of the filter media after just an hour of running, and saw mostly just a lot of fine dark green paint specks. These were not as apparent in the 15 hour inspection. Edit- I forgot to mention that I drained the sump and it was clean- the detergent oil and gravity filter do seem to work though not well enough to protect the rod bearing from some dirt.
I'll bet there are plenty of folks out there whose bearings and crank are being slowly ground away by internal dirt. Without Hotater's sharing his experience with his FuKing, I would have not known to check the upper bearing shell early, before damage to the crank.
I encourage other owners to check their upper bearing shell surface. Just because the sump is sand free on visual inspection does not ensure the lack of circulating dirt. I think Shipchief had a similar experience.
I'm going to be watching my bearing shells carefully in another 15 hours and see if my filter does the job, or if the contamination continues. I'm also interested in pursuing a filtered hollow dipper tube oiler.
Best Wishes,
Bruce M
Snowflake, AZ
Metro 6/1
This engine had a pretty clean sump on arrival, some crud but no signs of sand though the bearing shells were scratched from the factory test. (Shells replaced.) When I pulled the cylinder to have it planed and to hone it (it was not honed) I did poke and prod carefully inside the crankcase with dental picks and a mini spotlight and did not find any sand pockets or soft corners.
Bearing inspection at 15hrs of run time:
The lower shell was just slightly scratched, small particle type damage, with some pits where particles were embedded in the bearing. Without Hotater's advice to always check the upper shell, I might have stopped there thinking it didn't look too bad at all. There was no other sign of wear but the fairly minor scratch/pitting.
The upper shell has scratching and fine particles embedded near the oil holes, these scratches from the oil holes in the direction of rotation. There are also some significant, long scratches, and enough embedded (very fine) grit that putting them back in seems a bad idea. No other wear is evident.
So far, the crank isn't scratched up, the thick bearing material has done it's job.
I pulled my gravity oil filter box from below the breather door and pulled out all 7 bounty paper towels and the 100 tpi copper mesh screen at the bottom. The top two towels spread out showed a modest amount but wide variety of particles- some that might be fine sand, some fine metalic ones that look like brass, some clumps of soft gunk. The lower towels were clean but for the usual carbon soot. The screen just had paper fuzz and a few other specks of crud. The magnets in the filter box had very fine, soft metalic fuzz on each end. About the volume of two BB-s worth on each magnet.
I had previously changed the top of the filter media after just an hour of running, and saw mostly just a lot of fine dark green paint specks. These were not as apparent in the 15 hour inspection. Edit- I forgot to mention that I drained the sump and it was clean- the detergent oil and gravity filter do seem to work though not well enough to protect the rod bearing from some dirt.
I'll bet there are plenty of folks out there whose bearings and crank are being slowly ground away by internal dirt. Without Hotater's sharing his experience with his FuKing, I would have not known to check the upper bearing shell early, before damage to the crank.
I encourage other owners to check their upper bearing shell surface. Just because the sump is sand free on visual inspection does not ensure the lack of circulating dirt. I think Shipchief had a similar experience.
I'm going to be watching my bearing shells carefully in another 15 hours and see if my filter does the job, or if the contamination continues. I'm also interested in pursuing a filtered hollow dipper tube oiler.
Best Wishes,
Bruce M
Snowflake, AZ
Metro 6/1
? One thought I had was to concrete a piece of pipe into the ground which could be strapped/clamped to the exhaust pipe, and would then bear the weight of the exterior pipe and muffler assembly. Then the wall mounts (pipe is 6" away from wall to avoid blistering the paint) would only have to bear lateral loads from wind. I'm not sure how to isolate the pipe from some sort of support brackets... 
You can just see the oil filter inside and below the breather door opening. The oil level sight/sensor works great.
I cannot pull the engine through compression no matter how hard I try- I have to rock it backwards to get the exhaust valve lifter in. This is new for me.