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Mercrusier 5.7 Making clunking noise

S

Stevo998

New member
Hello, I purchased a Cobalt 233 with a mercrusier 5.7 L and it started with the boot and ran good and quiet.
When I got it in the water and put it under load it started to make a clunking noise.
I was told that it ran good last time it was in the water 2 yrs ago.
I have since changed out the fuel and replaced it with high octane
Replaced the fuel filter
Replaced Spark plugs
Replaced the distributor cap and rotor
Replaced the bellows
Replaced the oil in lower unit
Greased and inspected the u joints
Starts up and runs fine but still makes a clunking noise under load.

Timing? Any ideas I will try to attach a short video clip. here shortly.
 

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AllDodge said:
That's pretty loud and doesn't sound good

How is the noise on plane?
Click to expand...
I didn't take it on plane as I did not to possibly risk serious damage.
I have since cleaned the throttle body and replaced gaskets and o rings along with o rings.
Also replaced the injectors.
Seems to run and idle smoother but still get the random clunking.
Could this be timing?
 
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