1990 350 Sundancer engine knock....

QT1

Active Member
Oct 20, 2016
644
Belair, MD
Boat Info
1990 350 Sundancer, "Quality Time II".
Engines
454 Mercruisers, performance parts modified by PO.
. title is 1990 Sea Ray Sundancer 454 engine knock.
I don't know if this link will work, but having the same engine knock on the starboard engine with less than 100 hours on each repowered engine. Would love to hear any suggestions. Thanks.
 
Doesn't sound loud enough to be a rod or piston knock. It seemed to get louder when you moved to the starboard side. Sounds related to the valve train. If you had a stethoscope you could narrow it down but try removing the starboard valve cover to inspect the rocker arms and pushrods.
 
The surveyor gave the same suggestions. I will have to wait until open season to run the engine and perform this diagnostic. Thanks for the input.
 
If I remember correctly, it's the same in either temperature. That is a good idea about collecting a oil sample. Thanks
 
It sounds to me like a rocker is too tight -- I don't claim to be a mechanic -- but in adjusting hydraulic rocker, we tighten down until knocked and back off (assuming these are hydraulic) this sound like that type knock. ---

Good luck
 
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Doesn't sound loud enough to be a rod or piston knock. It seemed to get louder when you moved to the starboard side. Sounds related to the valve train. If you had a stethoscope you could narrow it down but try removing the starboard valve cover to inspect the rocker arms and pushrods.
Tonight I will take a pic of the survey page showing the compression reading. Thanks Socks for the info. I'm taking all advise to work on this. I must say, the boat runs fine.
 
Surveyor?
Are you buying or selling this boat?
Or have you had it for a few years?
Bought the boat. Picked it up in November. Sold my 300 Weekender.
 
I agree, sounds like valve train noise. I'm not familiar with your particular application, but if its an adjustable valvetrain, one or more valves may need to be adjusted.

If it's non-adjustable, you may have a bent push rod, collapsed lifter or even a worn camshaft.

Remove the valve covers and look for excessive play in the rocker arm/push rod. You'll need to rotate the engine by hand, as you need to check each valve when it is completely closed.
 
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I agree, sounds like valve train noise. I'm not familiar with your particular application, but if its an adjustable valvetrain, one or more valves may need to be adjusted.

If it's non-adjustable, you may have a bent push rod, collapsed lifter or even a worn camshaft.

Remove the valve covers and look for excessive play in the rocker arm/push rod. You'll need to rotate the engine by hand, as you need to check each valve when it is completely closed.
Keep in mind, the engines were reconditioned with about 100 hours on them as of 9/17.
 
Congrats on the new boat. I would reset all valves. Are you planning on adjusting the valves?
I. will wait until the boats back in the water, then I plan on making an appointment to the place the po had the motor work done.
 
I had an engine with that sort off knock ! it was a fractured cracked rocker !
 
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