Thank you alldoge! I currently have a carb rebuild kit and will plan to start there. Then fuel line checking and main fuel filter at base of engine. Already changed the small filter screen at the fuel inlet to carb.
Engine idles fine and will run smoothly at lower rpm in neutral and in gear. After running smoothly on the lake for 15 min or so at 3500 rpm then running for 15 min at 1000 rpm smoothly all is good. Then i go to running at 3500 rpm again and it runs rough so i back the rpm's down to 1500 again...
Mercruiser 3.0 . bought a rebuild kit for my Mercarb. it runs well at lower rpm but higher rpm tends to run rough. I am thinking possible jets clogged and possible pump in carb the seal could be bad or going bad. Almost sounds like it is missing at higher rpm once the engine has ran a while...
Turns out it was the Water pump. Thank you all for your suggestions.
Ran it without the belt for a very short time to isolate the accessories.
Once belt was off the noise did not happen any more.
So took off water pump to see what was inside and making the noise.
Check out the video and see...
I will be doing a bit more checking with stethoscope and camera prior to any major removal of hardware. it sounds like it is coming from the left side of the engine. near the pushrod/lifter panel that can easily be removed. Do you know if the lifters are hydraulic lifters? I would think they...
The shift cable is set correctly as well. Initially it was set at 5.5 with a pinned barrel nut. no adjustment could be made. So installed new stainless cable sleeve with adjustable barrel nut. Now the cable is set at 6.00" on the money. Forward gear locks in place and reverse locks in...
Thank you for your suggestion about removing the drive. The sound could be transferring into the engine possibly. I will be scoping through the spark plug holes tonight just to take a peak.
I can run above idle speed and the noise does not always occur.
This is a tricky sound do to its...
Thank you for your input. I would never do that. I am not new to boating just this is a new boat to me. I do like your suggestion in taking off the lower unit and running then to see if it could be the problem.
