Harmonic Balancer

[mdmadlener]

Hello All!!<br />Would anyone know how to adjust the harmonic balancer on a 1991 Mercruiser V6? <br />I have some minor vibration when in neutral which might be the result is many problems. While operating the boat; the vibration goes away once I am on plane.<br />A gentleman I know was helping me perform a tune-up over the weekend and we were discussing the vibration. I said that the vibrations go away at higher rates of speed. He initially thought that the vibrations could be caused by an ailing "U" joint, but after he felt the vibration, he said with confidence that it is probably the Harmonic Balancer. <br />Thanks in advance for all assistance. Any and all help is much appreciated!

 

[LubeDude]

Re: Harmonic Balancer

I would have a hard time blaming a harmonic balancer for a vibration, and there isnt any adjustment on a Harmonic balancer. Unless it was found to have slipped on the rubber. You would know this because you couldnt time the engine with the original timing marks. I think I would look somewhere else. Take a compression test, Look at your spark plugs while they are out, check your sparkplug wires, Just a start.

 

[mdmadlener]

Re: Harmonic Balancer

I did a compression test when I purchased the boat last year and just replaced the plugs, cap, and rotor. Compression was like anywhere from 165 to 155 which is great from what I am told.<br />I don't know what could be causing the vibration and I am hoping that it is not an indicator of something larger. I am hoping that the Mechanic who winterized the boat did not align the motor correctly.

 

[LubeDude]

Re: Harmonic Balancer

Thats a posibility. I hate vibrations, they can be a real pain to locate.

 

[johnkc]

Re: Harmonic Balancer

do yourself a favor and pull the drive and inspect the u-joints and gimbal bearing and alignment.only then you can blame the engine.the v-6 of this era did not smooth out till approx 1400 rpm anyway.

 

[Bondo]

Re: Harmonic Balancer

Yep, What John Says...........<br /><br />A year or two after your engine was built,<br />They Added a Counter-Balance Shaft, under the intake, to Help settle down the Vibration Problems with the 4.3ls........<br /><br />BTW, There's NO Adjusting the Harmonic Balancer,<br />It's Either Good,..... Or JUNK..............

 

[DHPMARINE]

Re: Harmonic Balancer

mad1 If the balancer is causing the vibration,you'll most likely see it wobble when you crank the engine over,or turn by hand.Also lots of black dust on front of engine from belt wear.<br />DHP

 

[mdmadlener]

Re: Harmonic Balancer

No wobble on Start. <br />This motor is immaculate. I'm serious; you wouldn't believe how clean everything is. I have had it in Salt and everything and the motor just remains clean. When I was doing my maintenance, I removed the flame arrestor and wiped my hands along the intake manifold without even picking up anything. <br />You could white glove this motor without problems. <br />I am hoping that she is just a rought starter becuase an earlier reply stated that a motor of this vintage shakes until around 1400 rpm. That sounds like my girl!!<br />Thanks guys for all of your help!!<br />Mad

 

[Northern Eclipse]

Re: Harmonic Balancer

Have you checked if the prop is true, such has no bent ears or if in fact that it is in balance, and has been installed correctly with the correct hardware and has been torqued properly. If your not sure take it to your local prop shop, most of the time they will check'em for no-charge.

 

[mdmadlener]

Re: Harmonic Balancer

NE<br />Yes, we checked and trued the prop. <br />The vibration occurs whether the engine is in neutral or drive. The motor smoothes out as RPMs increase.