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Topic-icon Cherokee 6/300 engine issue

  • Lachlan Oliver
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4 months 1 week ago #1396

Hello "everyone"
I am in a bit of a situation and wanted to get some advice. I bought a 1974 Piper Cherokee 6/300 in Oklahoma from a farmer. He was the second owner and the last overhaul on the engine was 20 years ago. He said he flew it once a month to keep the engine going, but not at all the last 2-3 years. The engine (IO-540-K1A5) has 412 hours on it and the Airframe only has 2,200 on it. I had it flown by a ferry pilot to Tulsa for a pre-buy inspection and annual. Long story short, the pre-buy didn't turn up anything and the annual took 3 months (at a FAA repair station) I also had the avionics all updated to a 750, but then had it flown out here to San Diego were I live. Now number 6 cylinder is flat, number 5 cylinder doesn't show one the EGT monitor and 4 out of the remaining cylinders are only producing 64% power on the Cam test which I was told is considered a failure for Lycoming engines. My mechanic out here is saying that I need to overhaul all 6 cylinders "or" get a complete engine overhaul since the engine is 30 years old and sat.

Any thoughts on what questions I can ask or which path forward as far as engine overhaul versus just the cylinders?

Last Edit: 4 months 1 week ago by Lachlan Oliver.

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4 months 1 week ago #1399

OK,please define some terms for me.
When you say the cylinder is flat, what does that mean?
# 5 doesn't show on EGT; that could be a probe or loose wire
I am not familiar with the term Cam test. Can you explain further?
What do you think? Does anything about the engine cause you worry?
Is it using a lot of oil?
Is it hard to start?
Do you have an oil filter? If so, has the shop removed it and cut it open? If they did, was there metal in the filter media?
Is it using more fuel than the book says it should at each power setting?
I'm trying to get enough data to determine if the engine is in trouble.
It's entirely possible that it is; inactivity does tend to cause problems in lifters and camshafts in Lycoming engines.
Please get back to me with a few answers and I'll do my best to help you further.
Steve

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  • Lachlan Oliver
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3 months 4 weeks ago #1410

Hello Steve,

I apologize for the late reply, I had to go on military duty for a bit. I am a medic. Thank you for your questions. I have answered the best I could below. Currently I have taken off the cylinders in order to inspect the lower half. The crank looks good. I was going to have the cylinders looked at with a place called "One Stop" in Oceanside.

When you say the cylinder is flat, what does that mean?
My mechanic said he hasn’t seen a “flat” cylinder in over 30 years. Meaning it wasn’t working at all. During a compression test is didn’t even hold and showed zero.

I am not familiar with the term Cam test. Can you explain further?
I apologize it was a compression test.

What do you think? Does anything about the engine cause you worry?
It would fly with a nose high attitude and I had to fly at night with colder air to get over some mountains in NM. I thought with 300 hp it should be no problem getting over the mountains even during the day with 90 degrees out.

Is it using a lot of oil?
I haven’t had it long enough to really know. Only had it for 10 hours now.

Is it hard to start?
Starts up fantastic!

Do you have an oil filter? If so, has the shop removed it and cut it open? If they did, was there metal in the filter media?
Only black specks which the mechanic said was burnt fuel / carbon.
Is it using more fuel than the book says it should at each power setting?
Flying it back from Oklahoma the fuel burn was good.

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3 months 4 weeks ago #1411

Thanks for your service.
Does your mechanic have a borescope? If he does ask him to take a look at the #5 and #6 cylinders. I expect he will see burnt exhaust valves. Cylinders must be removed if a burnt valve is found.
Ask your mechanic to pull #5. While it's being repaired get him to take a good look inside the engine at the camshaft and lifters to see if there is any evidence of rust, cam lobe erosion or lifter face pitting.
If everything looks good, re install the refurbished cylinder, follow the break in instructions and fly.
Change the oil after 10 hours, remove the filter and cut it open. If the only thing you find are a few small metal particles, you should be good to go.
If you find an eroded camshaft or lifters, the engine will have to be removed and repaired, or exchanged.
Letting one of our aircraft engines sit is "engine abuse" and often the engine doesn't recover without a lot of "therapy."
Lycoming engine's Achilles Heel is the camshaft and lifters. If they don't show any evidence of rust, pitting or erosion then refurbing the cylinders that need work will most likely get you going again.
Your mechanic is correct; a compression reading of 64 is below the serviceable level as defined by Lycoming. I don't like to change cylinders if my borescope inspection does not reveal mechanical damage such as a burnt valve or obvious cylinder wall scoring. If the compression is low due to gummed up ring lands, which prevent good sealing my experience is that change the oil a couple of times at short intervals and flying often will clean up the gumming that is restricting the ring sealing.
A very good borescope is available at Amazon for $200. It's the Oasis VA-400. Connect it to a laptop via a usb cable and get a good look at the inside of your engine.
Let me know what you find.
Steve

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