Lycoming O360-A4M CLicking/Ticking

idahoflier

idahoflier

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idahoflier
Hi,

I just noticed that my engine has a clicking/ticking sound. It's not loud, but it is noticeable especially during idle. I believe it's there at takeoff/cruise power but it's harder to detect due to the increased engine noise.

My thoughts are the source is probably related to:
1) Valve train on a cylinder.
2) Leaking exhaust gasket.
3) A bearing going bad.

I had a clean oil filter at the last oil change about 10 hours ago. My biggest concern is a possible bad bearing. If it is a bad bearing how long does it click/tick before it makes metal and/or fails? How reliable is oil analysis at predicting bearing failure?

Any other thoughts/opinions?

Thanks!
 
Have your A&P do a tappet clearance check. this is a symptom a cam lobe problems.
 
Tom-D said:
Have your A&P do a tappet clearance check. this is a symptom a cam lobe problems.
Click to expand...

Thanks for the insight, trying to touch base with my A&P now...
 
Unit74 said:
3 hours of soak time on the thread and you are smitten about no replies? :frown2:
Click to expand...

Well, at the time my question was 12 minutes old and I received some advice from a knowledgeable person that covered the first potential issue on my list, so yes, I was happy with the feedback.

I have since spoken with the IA that performed my annual and he suggested the same check...
 
Do O-360's not have a hydraulic lifter assemblies?
 
Went through some video and recorded a couple of samples if this helps to identify the source...
Chip Sylverne said:
If the noise lessens with rpm, might be a suspect.
Click to expand...

Yes, that's what the suggested tappet clearance check will check...
 
Chip Sylverne said:
Do O-360's not have a hydraulic lifter assemblies?
Click to expand...
They do, but their range of adjustment isn't that large. If, as Tom says, a cam lobe is wearing down, the lifter can only expand so much until it tops out and now we start seeing lash in the valve train, and we hear clicking.

A sticking lifter can do it, too.
 
I don't see how a worn cam per se would likely cause lash. Cam wear typically is at the nose (pointy) end of the lobe where the valve is open and the spring pressure high. The hydraulic lifter gets reset to zero lash at the base circle end of the lobe. There is no valve spring pressure at this time, only the relatively small pressure due to oil pressure and the internal spring of the lifter. This pressure is insufficient to cause significant cam wear.

OTOH, if the cam lobe nose is worn it is quite likely that the lifter is also worn and that could certainly cause lash.
 
flyingbrit said:
I don't see how a worn cam per se would likely cause lash. Cam wear typically is at the nose (pointy) end of the lobe where the valve is open and the spring pressure high. The hydraulic lifter gets reset to zero lash at the base circle end of the lobe. There is no valve spring pressure at this time, only the relatively small pressure due to oil pressure and the internal spring of the lifter. This pressure is insufficient to cause significant cam wear.

OTOH, if the cam lobe nose is worn it is quite likely that the lifter is also worn and that could certainly cause lash.
Click to expand...
Yup. You're right. I'd lean more to a sticking lifter. The internal piston doesn't move up as the cylinder expands and the lash increases, so clearances result and make noise.
 
When the lifter looks like this, it doesn't take long before the cam gone.
 

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Clicking could also be a leaky-bad/blown cylinder-to-exhaust gasket. On the ground during takeoff they sound like almost like a clicking. IOW could be a mis-diagnosis
 
Chip Sylverne said:
That's not a lifter. That's a cam follower. A stuck or collapsed lifter is inside that thing, and is a MUCH easier fix.
Click to expand...
Doesn't matter which nomenclature you put on that piece, your not going to have much lifter with out it..
I believe every one except you know it as a lifter.
And OBTW very few Hydraulic units can be changed with out removal of the lifter assembly
 
Chip Sylverne said:
That's not a lifter. That's a cam follower. A stuck or collapsed lifter is inside that thing, and is a MUCH easier fix.
Click to expand...
The lifter assembly is comprised of a cam follower and a hydraulic unit.It isn't called a lifter until it is assembled.
What you call a lifter is actually a "Hydraulic unit"
 
Well, here's hoping it's the "hydraulic unit"! ;-) I hope everyone has a Happy Independence Day!
 
I just had a similar issue on my Tiger that got resolved just this week. Everybody has their own way of describing a sound coming from an engine, but mine was kinda like what you describe...and most noticeable at idle. On top of that my #3 EGT was 250 lower than all the others. After compression and boroscope seemed fine, we found that the exhaust riser coming from the #3 was cracked right at the top where it attaches to the cylinder. 2 hours of labor to replace and everything is back to normal. Good luck.

9:00 into this video I made shows the repair:
 
Tom-D said:
Doesn't matter which nomenclature you put on that piece, your not going to have much lifter with out it..
I believe every one except you know it as a lifter.
And OBTW very few Hydraulic units can be changed with out removal of the lifter assembly
Click to expand...

Eau contraire! Nomenclature matters...a lot. Everyone may think what you pictured is a lifter, but it ain't. Replacing those is a major job. Replacing the hydraulic lifter is minor. It's easily removed from the Lycoming assembly by removing the pushrods and pushrod tubes. Just don't use a magnet and magnetize the check ball. I would check the dry lift at the valve, and if it's in spec, suspect the hydraulic lifter.
 
Chip Sylverne said:
Eau contraire! Nomenclature matters...a lot. Everyone may think what you pictured is a lifter, but it ain't. Replacing those is a major job. Replacing the hydraulic lifter is minor. It's easily removed from the Lycoming assembly by removing the pushrods and pushrod tubes. Just don't use a magnet and magnetize the check ball. I would check the dry lift at the valve, and if it's in spec, suspect the hydraulic lifter.
Click to expand...
The vast majority of Lycoming engine have lifters that can not be removed with out splitting the case.
 
Don’t they have what they call “mushroom “ lifter bodies ? Which means they won’t come out from the pushrods side, they have come out from the cam side and that is the reason splitting the case?
 
Mooneys R Quicker said:
Don’t they have what they call “mushroom “ lifter bodies ? Which means they won’t come out from the pushrods side, they have come out from the cam side and that is the reason splitting the case?
Click to expand...

Again, nomenclature. The tappet bodies cannot be removed without splitting the case. Hydraulic lifter asssemblies, which fit inside the tappet bodies, can be easily removed with a dental pick or hooked piece of safety wire. The tappet body (or cam follower) and hydraulic lifter are not one and the same.
 
Chip Sylverne said:
Eau contraire! Nomenclature matters...a lot. Everyone may think what you pictured is a lifter, but it ain't.
Click to expand...

Your nomenclature is just as incorrect, per the Lycoming IPC. But who’s counting right?
 
mondtster said:
Your nomenclature is just as incorrect, per the Lycoming IPC. But who’s counting right?
Click to expand...
Yeah, they call them plungers. But I found that nobody knew what I was talking about when I used lycomings terminology
 
Salty said:
Yeah, they call them plungers. But I found that nobody knew what I was talking about when I used lycomings terminology
Click to expand...

The correct name is tappet body. Chip finally called it by that name in his last post, after chastising Tom for incorrect nomenclature.

Although the term “cam follower” is reasonably descriptive and accurate (and what I usually refer to them as), it is not what Lycoming calls them.
 
mondtster said:
The correct name is tappet body. Chip finally called it by that name in his last post, after chastising Tom for incorrect nomenclature.

Although the term “cam follower” is reasonably descriptive and accurate (and what I usually refer to them as), it is not what Lycoming calls them.
Click to expand...
I was referring to the hydraulic part that can be replaced without splitting the case, not the follower that can’t.
 
I don’t get why everyone jumps on Tom.

He offers to help in many threads and then 3-4 of you just start picking at his posts and not helping the OP.

I don’t get it. Used to not be like that when I first came here years ago.
 
Terry M - 3CK (Chicago) said:
I don’t get why everyone jumps on Tom.

He offers to help in many threads and then 3-4 of you just start picking at his posts and not helping the OP.

I don’t get it. Used to not be like that when I first came here years ago.
Click to expand...

Nobody jumped on anybody until this post. And who posted it? Prior to that it was simply sharing information.

Tom-D said:
Doesn't matter which nomenclature you put on that piece, your not going to have much lifter with out it..
I believe every one except you know it as a lifter.
And OBTW very few Hydraulic units can be changed with out removal of the lifter assembly
Click to expand...
 
Salty said:
I was referring to the hydraulic part that can be replaced without splitting the case, not the follower that can’t.
Click to expand...

I know. The plunger, aka hydraulic unit, wasn’t what I was referring to in the post of mine you quoted.
 
Terry M - 3CK (Chicago) said:
I don’t get why everyone jumps on Tom.

He offers to help in many threads and then 3-4 of you just start picking at his posts and not helping the OP.

I don’t get it. Used to not be like that when I first came here years ago.
Click to expand...

Based on older posts I’ve read, I think Tom’s posting style has changed a bit in recent times, and he has brought at least some of the ire on himself. But I think people have taken it a bit far at this point, and for some reason made it personal.
 
mondtster said:
The correct name is tappet body. Chip finally called it by that name in his last post, after chastising Tom for incorrect nomenclature.

Although the term “cam follower” is reasonably descriptive and accurate (and what I usually refer to them as), it is not what Lycoming calls them.
Click to expand...

Actually, smart guy, I'm still incorrect. It's technically a hydraulic spherical tappet body, according to the Lycoming SI 1011N on such matters. So there, take that.
 
Terry M - 3CK (Chicago) said:
I don’t get why everyone jumps on Tom.

He offers to help in many threads and then 3-4 of you just start picking at his posts and not helping the OP.

I don’t get it. Used to not be like that when I first came here years ago.
Click to expand...

I'm not jumping on Tom. I have a lot of respect for his experience and opinion. The problem may well be spalling between cam and follower. All I was trying to point out was there is a name for the intermediate part between that is a cheap, easy check before pulling a jug.
 
Update: The shop looked at my engine and found a few pushrod tubes that had dents, one of which that was severe enough that the pushrod was contacting the tube. The shop was unable to definitively identify where the ticking noise was coming from using a stethoscope but felt the noise was loudest on #1 which had the previously mentioned pushrod/pushrod contact issue. #1 cyl had been replaced in the past about 450 hrs. ago. #1 cyl shows scoring, but the shop is unable to determine how bad with the borescope. All valve/lifter clearances checked out to be well within spec. Magneto impulse coupling has been ruled out. I have put on about 150 hrs on this engine since I have owned it and have performed all the oil changes during that time and have never found any metal in the oil filter. The shop examined the current oil filter which had about 10 hrs on it and found no metal.

The pushrod tubes were replaced and everything put back together. The shop believes the ticking is reduced but still present.

I go through a qt of oil ever 5 - 6 hours and keep the sump at 6 qts. I have found that any more than 6 qts gets blown out rather fast, so there is some blow by, but it’s not horrendous.

Soooo... At this point the thought is that the noise is likely due to piston slap, perhaps due to an oversized cylinder when it was replaced. They feel that because there is no history of metal it is probably safe to fly and monitor the situation. The engine is 26 years old at approx 1807 TT with a TBO of 2000 hrs.

So it seems if it’s not piston slap the other candidates are a worn wrist pin or a bearing, although it seems a bearing would go rather quickly. None of this bodes well so I think I’m going to fly and monitor for the next few months while I get things lined up for an overhaul.
 
Piston slap generally has a slightly metallic, bell-like resonance to it from the piston skirt, not really a sharp tick, and usually goes away when engine temps warm up. Don't like the finding of cylindr scoring, but no metal is filters is good.

Sorry there's nothing definitive.
 
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Agreed, doesn’t sound like piston slap.

EDIT: Oops, I was thinking this was a different thread. Can’t comment on this one.
 
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