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engine noise

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marylou
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engine noise

Post by marylou » Sat Jun 03, 2017 3:11 pm

I have a 1960 ChrisCraft Continental. It has a 283cc chevy with about 100 hours.
We took it out today and were cruising about 2500 rpm and a loud knocking sound occurred.
It was about once a second. When I backed off the rpm to 1500 the noise went away for awhile, then stated again.
I slowed it down to idle speed and no noise for a little while, then the knock again, never more than once a second.
Drove it back to marina after an hour wait and no noise at idle cruising speed, until 20 minutes, then the knock.
The knock is still there in neutral with output shaft not spinning.
Any ideas?
Sounds like the noise is coming from cylinder head area.

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island time
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Re: engine noise

Post by island time » Sat Jun 03, 2017 6:46 pm

I know you mentioned a time interval but I have to ask; does the noise speed up or slow down with engine speed?

Craig Wilson
Craig Wilson
Churchville, NY
Alexandria Bay, NY

1968 23' Chris Craft lancer
1971 31' Revelcraft
1988 25' Fourwinns
1972 19' Chris Craft Lancer
1957 18' Chris Craft Sea Skiff
1958 18' Chris Craft Sea Skiff
1968 23' Chris Craft Commander

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robertpaul
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Re: engine noise

Post by robertpaul » Sat Jun 03, 2017 7:50 pm

good question. if it varies, I'm thinkin' head gasket. Easy fix if it is.
1937 35' Double Stateroom Enclosed Cruiser

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island time
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Re: engine noise

Post by island time » Sun Jun 04, 2017 8:38 am

The sound you describe doesn't say head gasket to me. You mentioned that the engine only has about 100 hours on it since rebuild but it hasn't made the noise until now?
Is it a light "tick tick " kind of sound or is it a heavy knocking sound and is it just sound or do you feel it in the frame of the boat?
Is there any water in the oil? (oil looks like a milkshake)?

Craig Wilson
Craig Wilson
Churchville, NY
Alexandria Bay, NY

1968 23' Chris Craft lancer
1971 31' Revelcraft
1988 25' Fourwinns
1972 19' Chris Craft Lancer
1957 18' Chris Craft Sea Skiff
1958 18' Chris Craft Sea Skiff
1968 23' Chris Craft Commander

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Captain Nemo
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Re: engine noise

Post by Captain Nemo » Sun Jun 04, 2017 9:01 am

It is very hard to diagnose something like this w/ out putting an ear to it. By your description, (and I am guessing here) it could be a collapsed lifter if you have hydraulics. If they're solids, could be just an adjustment needed? Perhaps a slightly bend pushrod? IDK.
Boats are to be made of wood, otherwise, God would have grown fiberglass trees.

joanroy
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Re: engine noise

Post by joanroy » Sun Jun 04, 2017 9:26 am

I'd check the oil for water, pull the plugs and check to see if there all carboned the same, do a compression test and take it from there. If all that checks out OK I'd pull the valve covers and have a look or get an experienced mechanic to have a listen.

How's the oil pressure?

jfrprops
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Re: engine noise

Post by jfrprops » Tue Jun 06, 2017 8:28 pm

I don't like that story. Once a second? hummmm? not that often really? water pump? Chunk taken out of a belt and hitting something? Take a listen with a wooden dowel pressed to the engine and at your ear....get you close to the source maybe.
All other things related to that sound will likely be pretty serious and not fun. It seeming to be absent at first and then when it heats up it knocks.....scary.... I think the valve suggestion would be more of a clik than a knock. Do pull the plugs and compare.

good luck, keep us posted.

John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

charlesquimby
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Re: engine noise

Post by charlesquimby » Sat Jun 10, 2017 12:45 pm

Could be pushrod. Had this happen on my 68 Chev with new heads. Pushrod will bounce off of the lifter and hit inside of the valve cover... CQ

jfrprops
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Re: engine noise

Post by jfrprops » Sun Jun 11, 2017 2:33 pm

Hey, yeah....I like the push rod idea.....should have suggested that myself....investigate along those lines....

John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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Bilge Rat
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Re: engine noise

Post by Bilge Rat » Mon Jun 12, 2017 6:28 am

I had a bent pushrod on my Gray 327 and didn't even know it. No noise, no performance issues that I could detect. I was going to do a valve lash check/adjustment on the engine after 100 hours running and as a check, you get each cylinder at TDC with both valves shut and rotate the pushrod in your fingers. Found one that wobbled and removed the head. The pushrod had witness marks where it rubbed against the casting of the head but no other damage. Rocker, lifter and cam okay. While the valve was pulled had the machinist polish the valve stem and guide as it may have been too tight in the guide. Never will know what happened or when for sure.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

jfrprops
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Re: engine noise

Post by jfrprops » Mon Jun 12, 2017 8:15 am

yeah...you never did know what happened or when...but you were smart enough to know what FOR SURE was going to happen if you didn't fix it. Good advice/lesson there.

John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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