Discrepancies I find during tear down

[Tom-D]

most of these pictures are from 0-300/0-200 engines I have rebuilt. but are typical of why we rebuild engines.

picture
1, over heated rings on break in high oil consumption
2 pitted gear teeth cause by electrolysis from setting long periods
3 FOD rattling around in the case
4 The FOD, broken stud and nut from a thru case stud in a Franklin.
5 pitted cam
6 messed up generator drive
7&8 corrosion in front sump of a 0-300-A off a early 172
9 corroded threads on case thru bolt
10 fretting case at main bearing support web
11 broken spacer due to over torquing the case half trying to stop case seam leak.
12. sludge in sump from running W-80/100 with no filter.

 

[denverpilot]

Just asking.

7 & 8... What "bad" is going to happen? It looks like an opportunity for insane amounts of stuff in the filter, and if that stuff goes into bad places, worse will happen... But is that the danger there?

The sludge... Same question, but even less likely to go anywhere or do anything if it's been sitting there for lots of hours, right?

Just curious. I don't like any of them, but those looked "less dangerous" to my untrained eye. Especially the sludge.

Not ideal, as Mr. White would say.

 

[Apache123]

#12, is using 100W bad if you have a screen instead of a filter, or is it something else?

 

[Tom-D]

#12, is using 100W bad if you have a screen instead of a filter, or is it something else?

The picture shows a layer of sludge that is a mixture of lead, water and oil. the white stuff is the mag corrosion deposits made when the mag gets attacked by the water.

I simply blasted away the corrosion and will treat the mag with magnadine, and continue in service. this one is pretty mild they will corrode all the way thru until we see a leak.

 

[Tom-D]

Just asking.

7 & 8... What "bad" is going to happen? It looks like an opportunity for insane amounts of stuff in the filter, and if that stuff goes into bad places, worse will happen... But is that the danger there?

The sludge... Same question, but even less likely to go anywhere or do anything if it's been sitting there for lots of hours, right?

Just curious. I don't like any of them, but those looked "less dangerous" to my untrained eye. Especially the sludge.

Not ideal, as Mr. White would say.

the mag corrosion deposits are hard as a rock and will stay under the layer of sludge.

the sludge is what we want the filterless engines to do, W100 will allow the bad stuff to drop out into the sump, using a "D" oil we need a filter.

be care full when you flush an engine with out a filter, you can break this stuff loose and run it thru the oil system. That usually doesn't happen, but it could. It took over night in the tank, and a steam cleaner to get it out to see the white mag corrosion.

 

[Tom-D]

#12, is using 100W bad if you have a screen instead of a filter, or is it something else?

Using a W80/100 is a good thing with out a filter. it allows the heavy stuff to drop out to the sump rather than going back around the oil system again.

 

[Geico266]

Good stuff Tom.

It is easy for the untrained eye to look at some of that stuff and not see the problem. Broken stud, got that. Some of the others, not so much. Thanks for posting.

 

[SCCutler]

Tom, these are fascinating and, for the mechanically-inclined but untrained (like me), very informative.

Please describe better for me what I am looking for in the picture with the case fretting- not seeing what's there to see!

 

[Tom-D]

Tom, these are fascinating and, for the mechanically-inclined but untrained (like me), very informative.

Please describe better for me what I am looking for in the picture with the case fretting- not seeing what's there to see!

Note the worn area around the thru bolt hole in the bearing web. That area is supposed to be flat.

When the thru bolt broke, that allowed the case to move and wear, then they replaced it and over tightened all the thru bolts, that destroyed the bearing clearance due to the wear of the case, IOWs when the bearing web wore, there was nothing to stop the line bore from becoming oval rather than round. They came pretty close to having a bearing failure in this engine.

Note the crack in the front main bearing web, which is the thrust bearing??

 

[Tom-D]

Good stuff Tom.
Broken stud, got that. Some of the others, not so much. Thanks for posting.

That broken stud was in a Franklin 165 that I rebuilt several years ago. It's interesting to note the contamination in the insert bearing next to the stud. That got there by traveling thru the oil system and being stuck into the soft bearing material, which caused the crank bearing to get grooved requiring a regrind and under sized bearings.

Had that happened to a crank that was already as small as we allow you get to find another Franklin crank.