Top End Overhaul - Questions

[MyNameIsNobody]

Data Point: I bought a '66 that had 1,000 since overhaul...Not really.  It had 1,000 since an AD to inspect the crankshaft.  This was in 73 or 74.  I bought a plane with 1850 total time on airframe and engine.  At 1950 I Gupped the plane.  Elected to overhaul.  All accessories/hoses etc. at that time.  The cylinders had NOT EVER been overhauled.  I elected to oversize the cylinders vs. replacing.  I am now 14 years and 700ish hours post overhaul on those cylinders.  I am happy that I went the oversize vs. replace with new Lycoming route.

I hope you have success.  I would assume NOTHING on an overhaul.  Especially one that does NOT have detail in logs.  My logs on the engine overhaul are VERY detailed on what was replaced/re-built to include parts list with serial numbers.  I too had "none of that" on the first "overhaul" that WAS NOT.

[cliffy]

7 hours ago, Shadrach said:

I'm curious, why would you bother re-ringing 500hr cylinders?

In my opinion rings are the highest wear item in the engine. Sliding friction on the cylinder walls. It's cheap and easy to hone and re-ring and start off with new specs in this case if everything measures out good. I have never re-used rings. Wasn't taught that way 50 years ago and still follow what I was taught. I feel better doing it that way. 

 

[Shadrach]

3 hours ago, MyNameIsNobody said:

Data Point: I bought a '66 that had 1,000 since overhaul...Not really.  It had 1,000 since an AD to inspect the crankshaft.  This was in 73 or 74.  I bought a plane with 1850 total time on airframe and engine.  At 1950 I Gupped the plane.  Elected to overhaul.  All accessories/hoses etc. at that time.  The cylinders had NOT EVER been overhauled.  I elected to oversize the cylinders vs. replacing.  I am now 14 years and 700ish hours post overhaul on those cylinders.  I am happy that I went the oversize vs. replace with new Lycoming route.

I hope you have success.  I would assume NOTHING on an overhaul.  Especially one that does NOT have detail in logs.  My logs on the engine overhaul are VERY detailed on what was replaced/re-built to include parts list with serial numbers.  I too had "none of that" on the first "overhaul" that WAS NOT.

I think all of the early A1As went through the AD. When they did ours it was pretty close to an OH.

[carusoam]

When did the exhaust valves change on many Mooney engines?

Diameter of one of the parts in the chain...valve or push rod...

Just another thing to know what you have before deciding what to replace.

Best regards,

-a-

[Shadrach]

4 hours ago, irishpilot said:

Shadrach, the log showed 480 hrs when it was overhauled. It makes no mention of specifics accomplished. I will assume that the cylinders were overhauled and not replaced. The engine currently has 1180. So the cylinders have 1180 SMOH and 1660 TT. Am I doing the math right?

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I think your math work is correct. Does the 1660TT calculation match the total airframe time? If you can determine with reasonable confidence that the cylinders have 1660TT on them, then OH is certainly a viable option.

Edited February 6, 2016 by Shadrach

[Shadrach]

20 minutes ago, carusoam said:

When did the exhaust valves change on many Mooney engines?

Diameter of one of the parts in the chain...valve or push rod...

Just another thing to know what you have before deciding what to replace.

Best regards,

-a-

Early 60s I believe.

 

[irishpilot]

4 hours ago, irishpilot said: Shadrach, the log showed 480 hrs when it was overhauled. It makes no mention of specifics accomplished. I will assume that the cylinders were overhauled and not replaced. The engine currently has 1180. So the cylinders have 1180 SMOH and 1660 TT. Am I doing the math right?

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I think your math work is correct. Does the 1660TT calculation match the total airframe time? If you can determine with reasonable confidence that the cylinders have 1660TT on them, then OH is certainly a viable option.

Yes, it does match.

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[Guest]

Here is the copy of Lycoming SI1009AW which lays out TBO.  Note 5 covers various changes in TBO by year and mod level.

http://www.lycoming.com/portals/0/techpublications/serviceinstructions/si1009aw_recommended_tbo_periods.pdf

Clarence

[N601RX]

In addition to the 7/16 valve stem, there was also smaller bearing  dowels used up until the early 70's that reduced TBO to around 1200 hrs.  When we overhauled our engine a few years ago we were surprised to find we still had these. 

 

[M20F]

1 hour ago, Shadrach said:

Early 60s I believe.

 

My 67 had the 7/16 valves so at least till then.

[Shadrach]

1 hour ago, M20F said:

My 67 had the 7/16 valves so at least till then.

Interesting. I do not think ours did, but it went back to Lycoming in the early 70s for an AD. What's more interesting is reading the Lycoming service instruction that Clarence posted? It does not appear (at least in how I read it) that "Note 1" which covers the 7/16 valve and 1/2"valve is applicable to the "A" series IO360. Am I missing something or is this service instruction suggesting that all IO360 A1A engines came with 1/2" valves?

[carusoam]

When I bought the 65C in Y2K it seemed that making sure you have 1/2" stems was an important PPI issue of the time.  Most planes had been through an OH by then having them replaced.  The 2000hr TBO was the key.  Especially when buying it with 1000+ hours on it already.

Best regards,

-a-

[Shadrach]

1 hour ago, carusoam said:

When I bought the 65C in Y2K it seemed that making sure you have 1/2" stems was an important PPI issue of the time.  Most planes had been through an OH by then having them replaced.  The 2000hr TBO was the key.  Especially when buying it with 1000+ hours on it already.

Best regards,

-a-

That corresponds with the SI as almost all the O360s are listed as potentially having 7/16 valves, IOs, not so much.

[irishpilot]

I found those notes as well. So, just to make sure I understand, if the engine has 7/16 valves TBO is 1200 and 1/2 TBO is 2000? Also, any way to tell if it is a wide deck or narrow? I've read conflicting info. 

[N601RX]

If it uses regular hex nuts to hold the cylinders on then it is wide deck.  Narrow deck uses an internal Allen wrench style nut. 

[bonal]

13 minutes ago, N601RX said:

If it uses regular hex nuts to hold the cylinders on then it is wide deck.  Narrow deck uses an internal Allen wrench style nut. 

So now I know I have a narrow deck and I have seen these terms used on other threads what are the differences?

[cnoe]

Internal hex NUT? Like this?

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[N601RX]

14 minutes ago, cnoe said:

Internal hex NUT? Like this?

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Similiar, but it's either a 12 point or some kind of spline.  I think Lycoming quit producing narrow deck engines back in the 70's or 80's. The same models are now available in wide deck.

[Shadrach]

32 minutes ago, N601RX said:

Similiar, but it's either a 12 point or some kind of spline.  I think Lycoming quit producing narrow deck engines back in the 70's or 80's. The same models are now available in wide deck.

IIRC most of the case overhaulers will not overhaul a narrow deck case.

[bonal]

Not an internal hex nut but an internal hex bolt. Would these be used on a narrow deck exclusively or if OH within the last ten years would they use internal vs normal hex bolts

[Shadrach]

3 hours ago, irishpilot said:

I found those notes as well. So, just to make sure I understand, if the engine has 7/16 valves TBO is 1200 and 1/2 TBO is 2000? Also, any way to tell if it is a wide deck or narrow? I've read conflicting info. 

Yes, but "Note 1" (which relates to 7/16 valve size) in the Lyc SI does not appear to apply to the IO360A1A. Please let us know what is in your engine.

[irishpilot]

The engine is a wide deck and 1/2" valves. Took a while to get all the aluminum housing off as well as the lower cowling. Mooney aircraft do not have a lot of free space! Going to pull the jugs off tomorrow.

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[irishpilot]

I pulled the jugs off and found evidence of blowby on the pistons as well as evidence of where rust formed on the cylinder walls. Pistons were pretty wet with oil and carbon buildup. Initial inspection of crankcase and cam looks good. No excessive wear. Here's a few shots. I'm dropping off the cylinders tomorrow. I'll be interested to see the engine shop's assessment. What do ya'll think?

[Andy95W]

Seen worse, but that first piston- yuck.

IRAN with new rings for all 4 would probably be a nice option to keep the price down instead of actually overhauling all 4 cylinders.

[carusoam]

Any missing or broken rings?

Did all four do the same thing evenly?

Best regards,

-a-