Intermittent engine clicking

K

kaliona

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Sep 27, 2008
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1978 Mercruiser, 165hp 6 cyl. I'm getting intermittent clicking or chattering from what I think are the valves, or maybe lifters (I know nothing about valves and lifters, I just searched google and read this may be the cause of the noise). It will happen at both idle speed and cruising speed. I'll stop the boat, fish a little, and when I fire it up again to move, the noise is gone and engine purrs like a kitten. Stop to fish for a while, start the boat up, and it may or may not make that clicking noise. When I got home, I put the earmuffs on, started the engine...no noise. I recently changed the oil with 30 weight and the dipstick indicates proper level. First, am I hearing valve noise? Second, will I do damage to the engine if I keep running it in this intermittent chattering condition? I'm afraid to venture too far from the docks fearing the engine might quit on me.
 
Haut Medoc

Haut Medoc

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Re: Intermittent engine clicking

Hard to say without hearing it.....
Get a mechanic's stethescope to try & locate noise.....
Sometimes a bit of grit will cause a sticky lifter.....
How is the oil pressure?.....:confused:
 
T

TilliamWe

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Re: Intermittent engine clicking

I wonder if the "flapper" in your exhaust is making the noise. It's really called a shutter. And it's in the exhaust pipe that bolts to the inner transom plate. They can rattle intermittently.
 
K

kaliona

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Re: Intermittent engine clicking

The noise doesn't sound like in the area where the exhaust shutter is. so far I can't get it to duplicate the noise when I'm at home in my driveway. I'll bring my stethescope and try to isolate the sound the next time it does it. Again, if it is a lifter, is it bad to keep running the boat when its making the noise? Also, oil pressure is good while at cruising speed. Haven't made note of where it is at idle. What should it be at idle?
 
Haut Medoc

Haut Medoc

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Re: Intermittent engine clicking

Anything above 10psi would be OK at idle.....
I don't think I would sweat it if it is intermittant, but I would try to localize the noise.....
If it keeps recurring in the same spot, I'd look at the lifter....;)
 
ziggy

ziggy

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Re: Intermittent engine clicking

achris wrote up a post on this some time ago. although i can't find it. it was regaurding the L6 chevy engine. if i remember right. it was wrist pins clattering when cold. as it warms up and everything gets hot and expands, the noise will go away.

fwiw. i have this clicking noise too. i'm not overly concerned about it as it goes away after it warms up. just like yours, just like achris described.... achris?
 
chiefalen

chiefalen

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Re: Intermittent engine clicking

Vacuum test tells everything.

Lost art really most guys don't perform one.
 
R

rheine

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Sep 13, 2008
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Re: Intermittent engine clicking

Good luck and report back on your noise issue. I just learned a ton off that vacuum link. The more ways to track down the real problem before turning a bolt or trying a new part the better.
 
chiefalen

chiefalen

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Re: Intermittent engine clicking

The great part about the gauge is you can keep it on the boat, something unusual happens, you can pinpoint the problem, or was it just your imagination.

The dash mounted ones are a great idea.

That link i posted also had other links to other testing equipment, and how to use them.

Enjoy, glad i could be of a little help.
 
MikDee

MikDee

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Re: Intermittent engine clicking

CHECK THIS, The crankshaft pulley for the belt, make sure the bolts are not loose.
I had a Chrysler Lebaron 4cyl. a few yrs ago that had a noise like you describe. The engine ran like a top, but it had an intermittent clicking that drove me wild! It was hard to diagnose, especially being front drive with a sideways engine. I finally had a chance to get it up on a lift in the garage for tires, and I asked the guy to check it, Sure Enough that was the problem! he tightened the bolts, and all was fine. Let me know how you make out?
 
K

kaliona

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Re: Intermittent engine clicking

Replaced the plug on my intake with a fitting in order to hook up a vacuum gauge. I got a vacuum reading of about 16 psi. It wasn't holding "completely" steady, but had a slight shake between 15.5 and 16 psi. Based on the link chiefalen provided I'm going to consider that reading as normal. I'm still trying to isolate the noise, but with the vacuum reading I measured, does that rule out valves and lifters?
 
chiefalen

chiefalen

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Re: Intermittent engine clicking

A 30 year old boat i would say that it is in excellent health.

Go out and enjoy keep up with the oil changes and all you will be just fine.

To ease your mind a little i hope, it could be the fuel pump, oil pump.

If you wanted to, you could do a mild rebuild and have the heads rebuilt, but why?

Runs good, i bet it don't burn one drop of oil, does it?

Good luck.
 
MikDee

MikDee

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Re: Intermittent engine clicking

Did you check the item I said? Clicking could be one of many things, It's kind of hard diagnosing from afar, without hearing it, but I've heard alternators click, or power steering pumps, or water pumps, or distributors, or lifters, but chattering, I don't know what you mean?
Preigniton from advanced timing could sound like clicking to the untrained ear.
 
chiefalen

chiefalen

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Re: Intermittent engine clicking

Could be a pulley bolt came loose, seen it myself. Thats a good call. Very good call.

Why a very old motor i recommend not to start tearing apart is the danger of snapping off of bolts.
 
K

kaliona

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Re: Intermittent engine clicking

Thanks for the words of wisdom chief. I guess with my vacuum results and compression (130 to 145psi)should put my mind at ease. Getting stuck on the water is a lot different than getting stuck on the road in a car. You're right chief it doesn't burn any oil, I just have a slight oil leak I still have to find at the rear of the engine.

Mikdee, I'll check the crank pulley, and yeah I know it's tough to diagnose sounds over these forums so I do appreciate all yours and everyone elses suggestions. Maybe I'll just record the darn engine when it does it again and post an mpeg of the sound :confused:
 
chiefalen

chiefalen

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Re: Intermittent engine clicking

That slight leak high or low?

Reason i asked could be a few different things.
 
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