Should I be concerned? Cracked nut & washers on the top of O-300d

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U-turn

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U-Turn
Am considering purchasing a 1962 C-172c with the O-300D (KMYV) and upon checking over the plane I noticed the top of the engine had cracked nut and washers (see pic). I was planning to do a prebuy but am curious to know if this is indicative of a serious issue. The owner abruptly stopped flying the plane 3 yrs ago and its sat in a hangar ever since. I see no oil on the ground or inside the cowl. Any suggestions / advice is greatly appreciated.
 

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It looks like cracked paint on the nut and a split lock washer gap. Additionally, the engine data plate has been tampered with.

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It may not be particularly concerning but it is not unreasonable to ask oneself why it is cracked.
Sure stuff gets old and breaks. Maybe it was a defective nut.Should they all be changed or at least inspected?
How about this; maybe someone has overtorqued it. What about the others? What about the bolts, not just the nuts. Or what happens to the case flange when a nut if overtorqued; should one be looking for cracks there now?
You can go down a rabbit hole of worry. Why not have an A+P look it over?
 
jetiq said:
the engine data plate has been tampered with.
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It looks like it has been replaced, using new holes - are those not the original holes barely visible?
And it looks like differing cylinders, probably had a replacement at one point.
Are those intercylinder baffles at a wonky angle? I've seen them installed reversed, before.
 
Let'sgoflying! said:
It may not be particularly concerning but it is not unreasonable to ask oneself why it is cracked.
Sure stuff gets old and breaks. Maybe it was a defective nut.Should they all be changed or at least inspected?
How about this; maybe someone has overtorqued it. What about the others? What about the bolts, not just the nuts. Or what happens to the case flange when a nut if overtorqued; should one be looking for cracks there now?
You can go down a rabbit hole of worry. Why not have an A+P look it over?
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Mechanics aren't clairvoyant.
 
Are you sure that’s not cracked paint? I’ve never seen a cracked nut. Very unusual. Regardless, it wouldn’t concern me to simply replace it.
 
U-turn said:
I see no oil on the ground or inside the cowl. Any suggestions / advice is greatly appreciated.
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Is there any oil in the crankcase? Maybe it is like the old Harley's. If it isn't leaking oil, it is time to add some.
Did you start the engine?
 
After zooming in it doesn't appear like the "crack" in the nut goes all the way through. It doesn't look like paint. It almost looks like it was partially cut into. Weird. Nuts don't generally crack.

PREBUY.
 
Thats what happens when you use a cell phone during takeoff.
 
I do pre buys when it makes sense. What state is this located?
 
It does look like a split lock washer. Physically examine the nut and report back. The more I look at it, the more I agree with jetiq--it looks like paint.
Yes, the inter-cylinder baffle looks wonky or loose.
Look through the logs/ask about a cylinder replacement.
 
More than the nut, I’d have questions about the “abruptly stopped flying” part. Was it a pilot issue, or a plane issue? If the latter, what was it?
 
Domenick said:
It does look like a split lock washer. Physically examine the nut and report back. The more I look at it, the more I agree with jetiq--it looks like paint.
Yes, the inter-cylinder baffle looks wonky or loose.
Look through the logs/ask about a cylinder replacement.
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Yep, split loc-washer..
I believe the data plate was replaced a long time ago. (pretty common)
I see no discrepancy worth worrying about.
 
It definitely a split loc washer. Crack in the nut is hard to tell but I’m betting it’s paint.
I’ve seen a few data plates replaced like that but it’s been many years ago. Not sure why the engine shop would do that?
 
Plenty of legit reasons why an engine data plate may have been moved or altered.
 
That nut looks suspicious to me.

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Look at the gap between the nut and stud at the 2:00 position, too.

Besides that, the intercylinder baffle supports (in the original picture, on the other side of the engine, are badly tilted and about to fall between the cylinders.
 
Dan Thomas said:
That nut looks suspicious to me.

View attachment 91802

Look at the gap between the nut and stud at the 2:00 position, too.

Besides that, the intercylinder baffle supports (in the original picture, on the other side of the engine, are badly tilted and about to fall between the cylinders.
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Typical, no worries.

No one is worried with the bolt that is too long?
 
Checkout_my_Six said:
Replace the nut and bolt....and fly on.
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Agreed....the OP could just replace it and fly on...after he makes sure that his pre-buy includes a a startup and runup, then oil change with oil analysis and a borescope. A Continental sitting unflown for three years...worrisome.
 
Dan Thomas said:
That nut looks suspicious to me.

View attachment 91802

Look at the gap between the nut and stud at the 2:00 position, too.

Besides that, the intercylinder baffle supports (in the original picture, on the other side of the engine, are badly tilted and about to fall between the cylinders.
Click to expand...

Looks like paint to me, a simple scrape with a screwdriver would make it obvious.
 
My vote is, leave it alone and fly
 
That's a self-locking nut. I have seen nuts like that somewhere but I have no idea where.

Or, someone has been using a hillbilly torque wrench?

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Thank you all for the great discussion and tips. I'm planning to check out the airplane this coming week to confirm the nut situation and will report back to this thread. I noted in previous discussions the suggestion for the Real Gaskets Push Rod Seal kit and addressing corrosion in the sump pan. Are there other "gotchas" I should be looking for with this era of airplane and engine that has ~900 hrs on it?
 
U-turn said:
Thank you all for the great discussion and tips. I'm planning to check out the airplane this coming week to confirm the nut situation and will report back to this thread. I noted in previous discussions the suggestion for the Real Gaskets Push Rod Seal kit and addressing corrosion in the sump pan. Are there other "gotchas" I should be looking for with this era of airplane and engine that has ~900 hrs on it?
Click to expand...
The sump will have to wait until some one removes the engine, the sump will not clear the engine mount.
the sump is about 3/16" thick in the area we worry about.
 
U-turn said:
addressing corrosion in the sump pan
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I double checked this, very few of that year/vintage have corrosion problem.
the early 172, that set in a nose down attitude do. the 1962 sets noes up.
 
Do all O-300 data plates have the corners cut off?
My Lycoming O-320 has square corners pinned at the corners.
 
Tom-D said:
I double checked this, very few of that year/vintage have corrosion problem.
the early 172, that set in a nose down attitude do. the 1962 sets noes up.
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OP will find out for sure when he has the engine borescoped while it’s in annual or during the pre-buy.
 
MacFly said:
OP will find out for sure when he has the engine borescoped while it’s in annual or during the pre-buy.
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Show me how you borescope the sump without disassembling the engine?

Even when you remove a cylinder, you are not going to see what you need to see in the sump.

It is oily and caked with sludge.
 

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Tom-D said:
Show me how you borescope the sump without disassembling the engine?

Even when you remove a cylinder, you are not going to see what you need to see in the sump.

It is oily and caked with sludge.
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Concern for corrosion on cylinders and cam lobes would be my reason for the borescope. Obviously.
 
MacFly said:
Concern for corrosion on cylinders and cam lobes would be my reason for the borescope. Obviously.
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Do believe a seller would permit a buyer to remove a cylinder on a pre-buy?
because that is the only way you will see cam/lifters.
 
You mentioned the engine hours but how many years has it been since overhaul?
 
Tom-D said:
Do believe a seller would permit a buyer to remove a cylinder on a pre-buy?
because that is the only way you will see cam/lifters.
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Do you believe that this engine doesn't need to be borescoped?
 
I would be more concerned about a Continental with no oil on the ground.
 
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