weird noise in my mercruiser

[ryan04]

hey guys, I took my 91 bayliner with a 3.0L alpha one out today for the first time since I bought it in january. She drove like a champion, the only weird thing is after about 45 minutes the engine slowed down even with the throttle at 3/4, to a very slow speed. Out of the exhaust there was more than usual blue and black smoke, the engine stayed running and idled beautifully while this was going on, so I turned towards the dock, put it in gear and drove slowly back, along the way I opened it up again and it drove like nothing ever happened hitting speeds upwards of 55+. What would cause that? as well there was a slight "ting ting ting" noise at the back of the engine that seemed to come and go, but was very evident when the boat stopped then was pretty quiet after it picked up again. At WOT you can't hear the tinging at all. What might that be as well? thanks.

 

[watermellonI]

Re: weird noise in my mercruiser

Hey Ryan,
Ting Ting or Tic Tic, Tic Tic could be low oil pressure, thats why you don t hear it at higher speed, need more info here too, what was the temp runnin?
What type of oil are you usin? How much time is on the motor?
Ive been told that regular motor oil tends to air-ate gets bubbles in it from bouncin around this causes air to get into the oil pump which will also drop your oil pressure and cause a tic tic. The back of the motor is the #4 cyl and is the farthest from the oil pump and you ll notice a drop in oil pressure there first.
Hope this helps, the pros will be able to help you more but they ll need the info I mentioned above.

 

[ryan04]

Re: weird noise in my mercruiser

it was deffinately a tic tic tic sound, the oil pressure seemed to be a little low, and I don't know what kind of oil is in there because it was winterized at a marine shop before I picked it up by the previous owner so what ever marine places use I guess. I don't know what the numbers are but, the oil pressure gage read just over a quarter so I don't know what that is. It seemed it a bit low to me and I remember thinking it seemed a bit low, as well the temperature was nice and cool. Any idea's?

 

[cbavier]

Re: weird noise in my mercruiser

it was deffinately a tic tic tic sound, the oil pressure seemed to be a little low, and I don't know what kind of oil is in there because it was winterized at a marine shop before I picked it up by the previous owner so what ever marine places use I guess. I don't know what the numbers are but, the oil pressure gage read just over a quarter so I don't know what that is. It seemed it a bit low to me and I remember thinking it seemed a bit low, as well the temperature was nice and cool. Any idea's?

Didn't you check the oil level on the dipstick? That's what it's there for. It should be checked before every trip out as well as belts and hoses.

 

[Bondo]

Re: weird noise in my mercruiser

the only weird thing is after about 45 minutes the engine slowed down even with the throttle at 3/4, to a very slow speed.as well there was a slight "ting ting ting" noise at the back of the engine that seemed to come and go,

Ayuh,......

Just a Wild Guess,......

Change the Fuel Filters,.... It sounds like it's going Lean,+ Detonating.....

You might want to give it a Complete Tune Up as well....

 

[ryan04]

Re: weird noise in my mercruiser

the oil on the dipstick was at full and it looked brand new, and all the hoses are in great shape, now the fuel filter does look a bit aged so I'll swap that out and It's booked in for a service. I was just concerned of the tic tic and the engine slowings, was a sign that the engine itself was in terrible shape, but it ran so good!

 

[Don S]

Re: weird noise in my mercruiser

Since this seemed to happen after prolonged running, it may be a partially plugged fuel system. One way to test it is in the link below.
Hook it up and see what it does IF the problem occurs again.

http://forums.iboats.com/showthread.php?t=167561

 

[cbavier]

Re: weird noise in my mercruiser

the oil on the dipstick was at full and it looked brand new, and all the hoses are in great shape, now the fuel filter does look a bit aged so I'll swap that out and It's booked in for a service. I was just concerned of the tic tic and the engine slowings, was a sign that the engine itself was in terrible shape, but it ran so good!

The ticking may be the water running through the manifolds. I have the same thing with the ticking on mine. I pulled the manifolds and there was nothing in them. The ticking can't be heard when accelerating. Only at Idle on mine so after I asked several Mechanics that was their explanation. I also noticed on mine. Two spark plug wires on the Distributer cap are sparking slightly. That's only visible at night when it's dark. I was told to put a little vasaline on each plug wire boot until I could change the distributer cap and wires. I have that to do yet. I'll have it tuned up next fall. It was tuned two years ago. So that is a couple things you could check on yours. If you change anything be sure you use only OMC parts.

 

[ryan04]

Re: weird noise in my mercruiser

thanks alot guys I'll test what I can, you guys are a huge help. I'll let you know what I find. thanks