Noise in top of motor, Mercury I-6 1000

[Doug Watson]

I just bought a Mercury 1000, 1968 model. At slow idle there is a noise either in the #1 cyl or in the flywheel area. It doesn't sound like a rod. It goes away if I increase the RPM by about 100rpms. The motor sat for about 4 years before I aquired it. It runs out good. Thanks for your help

 

[Reel Appeal]

Re: Noise in top of motor, Mercury I-6 1000

Wacky,<br /> If possible,please describe the noise you hear so members may better understand.Is it a squeal,knocking,clicking etc?High pitch?

 

[Solittle]

Re: Noise in top of motor, Mercury I-6 1000

Wacky, Have you run it on a boat in the water. If so describe what you hear and rpm at WOT. Might also be a good idea to do a compression check.

 

[mellowyellow]

Re: Noise in top of motor, Mercury I-6 1000

after sitting that long, did you do anything to<br />the motor before you cranked it over? a little<br />wd40 in the cylinders, hand crank etc??<br />could be a sticking ring, might want to try to<br />decarb it. a compression check is definately your<br />first step though.<br />good luck!<br />M.Y.<br />'70 merc 1150

 

[Gold Bear]

Re: Noise in top of motor, Mercury I-6 1000

Wacky <br /><br />Pull the flywheel and see if the stator is loose, or hitting the flywheel. If it is loose and hitting the flywheel, tighten it down, and test to make sure it is working ok.<br /><br />If it is tight and hitting the flywheel, the top crankshaft bearing is worn and needs replacing.<br /><br />Good Luck, Gold Bear

 

[Doug Watson]

Re: Noise in top of motor, Mercury I-6 1000

The engine had been cranked over before I got it. All cyls. have #1-145,#2-150, #3-142,#4-145,#5-105,#6-150. I ran it 3hrs. on water. It ran out excellent. The carbs are a little rough at idle. Probably need rebuild from sitting so long. The noise is kinda like a knock but doesn't sound like a rod knock. It only does this at slow idle. It does it in gear or out of gear. I ran a 25:1 mixture when I tried the engine since it had been sitting so long. Thanks for your help.

 

[dkondelik]

Re: Noise in top of motor, Mercury I-6 1000

#5 -105 Sounds LOW! Rule of thumb. All cylinders should read within ~10% or so, of each other<br />Suggest decarb (to free stuck ring). <br />If compression doesn't come back, might be more serious. Might pull exhaust cover, check piston/cylinder for scoring or other damage.<br /><br />Good Luck!

 

[Waterbugtoo]

Re: Noise in top of motor, Mercury I-6 1000

With that compression, its probably #5 piston skirt slapping the cyl wall.<br /><br />