Mercruiser 3.0 Engine noise

[kf4nvm]

I have had this 1998 Stingray 180RS with a mercruiser 3.0 engine since March 2010. Bought the boat as a fixer up, but little did I know the engine block was cracked.

When I took the boat out on the lake for a test drive I noticed pinging or valve chatter, very light, but pronounced. This is the same time I noticed water in the oil and realized I had a cracked block. I had the block replaced and the engine rebuilt. When I took the boat back out after the engine was rebuilt I noticed the valve chatter was more pronounced at idle. This does not appear to be hampering the performance of the boat, still gets about 43 mph out of her.

I was wondering could it be the fuel, 87 octane (10% ethanol) from the local gas station? I have not had it long enough to try anything else in it, but have run two tanks of the same fuel through it?

I have checked oil pressure, 40 psi, checked the rocker arms to assure they are torque to specs. The noise appears to be valve chatter, almost sounds like a diesel.

 

[boat127]

Re: Mercruiser 3.0 Engine noise

sounds like a typical 3.0 to me

 

[Fordiesel69]

Re: Mercruiser 3.0 Engine noise

Please make a video. Thru text, we cannot help you diagnose noise issues.

An octane ping will sound like the engine is injesting pieces of glass. The 2.5L and 3.0L engines are not a quiet engine and never have been. There is alot of noise that can come from sloppy cam bearings, timing gears, valve train, piston slap, and most known piston pin (wrist pin)+ noise. Can you be certain the rocker lash is set correctly, all chevy's get done the same way. Many just snug them to one torque spec and call it a day. This is not correct!!

FWIW, when i was boat searching, every single 120 and 140 sounded like a diesel.

 

[kf4nvm]

Re: Mercruiser 3.0 Engine noise

I am out of town at the moment, but later this week I will get that video and upload. I have done a lot of goggling online and found that many say this engine is noisy. I have worked on car engines for many years, more as hobby not a career and I have noticed this type of noise from older engines, usually cam issues or worn lifters. The noise is definitely coming from the valve cover area, so I am leaning toward wear on the cam or lifters.

 

[cedarjunki]

Re: Mercruiser 3.0 Engine noise

checked the rocker arms to assure they are torque to specs. The noise appears to be valve chatter, almost sounds like a diesel.

1. Run engine until it reaches normal operating temperature, then remove valve cover.
2. With engine running at idle, loosen valve rocker arm nut until valve rocker arm starts to
clatter.
3. Turn rocker arm nut down slowly until clatter just stops. This is zero lash position.
4. Tighten nut 1/4 additional turn and pause 10 seconds until engine runs smoothly. Repeat
additional 1/4 turns, pausing 10 seconds each time, until nut has been tightened 3/4 turn
from zero lash position.


i havnt seen one yet that i havnt had to readjust this way.

 

[kf4nvm]

Re: Mercruiser 3.0 Engine noise

Completed the valve tightening and it appears to have worked, the valve chatter is gone. When I first started to tighten the valves they appeared loss? Can you tighten them too tight?

 

[cedarjunki]

Re: Mercruiser 3.0 Engine noise

yes you can go too tight.....only go the 3/4 turn past zero