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43 merc harmonic balancer

L

Lee Merrill

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"I have twin 97 4.3 litre merc

"I have twin 97 4.3 litre mercs on my 30 ft Maxum. The port engine developed a rattle at idle this weekend on an extended trip. Upon inspection I noticed what I think is the harmonic balancer "spinning" around the main pulley shaft. On the starboard engine, the balancer is firmly attached to the shaft. The port engine one appears to have come disconnected and due to the friction with the shaft as it spins has either worn the shaft or "stretched" the balancer ring? There is probably an 1/8 inch space between the balancer ring and shaft now. Also developed a fairly substantial oil leak in the same area. The engine ran fine otherwise for the 3-plus hours I ran it at 3400 rpm's (I had no choice - was 3 hours offshore!).

Any ideas or comments on why this would happen and what I should do next?"
 
"Lee
Get the balancer off the

"Lee
Get the balancer off the shaft and inspect the shaft for damage, normaly the balancer hub will chew out without damaging the crank but you need to get it apart and see what is going on.

Balancer was probably a bit loose on the shaft to start with and your problems have started from there.
If the hub is that badly flogged you will need to install a new crankshaft oil seal as well because that will be the cause of your oil leak.

By the way my option at 3 hrs off shore would have been to come home on 1 engine and turn the 3 hrs to about 4.5. An extra hour or so is much better and cheaper than pulling an engine and installing a new crankshaft if you have damaged it.

Cheers
Peter C"
 
"Peter,

Thanks a ton for th

"Peter,

Thanks a ton for the post. You're obviously right on. My follow-up question is How does the balancer connect to the shaft? I can't see any bolts or anything that indicates that the balancer clamps onto the shaft. How is a new balancer installed?

Regarding the offshore trip back, I tried just the one engine but was only making 8 knots vs. 25 with both engines. So I was looking at a nine hour trip instead of three, well beyond what I had left in the starboard fuel tank!

Thanks again."
 
"Lee

They are aligned with

"Lee

They are aligned with a key but on a slight taper, you will need to replace the key and you will have to drive the balancer on with a hammer.
If there is some crank damage and the balancer just falls on you may need to use a shaft grade loctite like 609 and let it sit for 48hrs before starting her up.

Cheers
Peter C

Fair enough call on the time to get back."
 
"[b]"you will have to driv

""you will have to drive the balancer on with a hammer."

That's a Great Way to Destroy a motor.......

Balancers are Pulled with a Puller,+ Installed with a Press..........."
 
"Bondo

With all due respect

"Bondo

With all due respect to you, in an ideal world when ever we removed and installed a pulley or a bearing we would use a puller and a press.

Unfortunatly we do not live in a ideal world and you cannot always get a puller or a bolt up press into the situation required to use them.

Now, I probably should have said, "Carefully tap the balancer back on", as is stated in many engine service manuals, so I will plead guilty to a poor choice of words, its not the first time and it wont be the last.

Yes, there is a possibility of doing damage when ever you apply any sort of force to the ends of a crankshaft, but to say I have replaced over hundreds of balancers in my time is conservative and out of those, there may have been only a handfull that the balancer could have been installed with a press when the engine was in situation.

Now , if the crankshaft end is threaded you can try using a bolt to pull the balancer back on but from experience this is only succesfull a portion of the time.

Unless Lee gets in there with a large lump hammer and bashes the crap out of it there is very little chance of him doing any damage to his engine.

How many engines have you stripped down and found damage caused by "Tapping" a balancer back on ?

Put it in an Automotive situation and ask yourself is a handfull of taps on a balancer going to do the same damage as thousands and thousands of applications of a clutch pushing load on the back of a crank ? very unlikely.

I certainly havent found one yet but I will make a point of looking for it in the future.

Respectfully
Peter C"
 
"peter
you hit the nail on th

"peter
you hit the nail on the head , good comeback.[i should have said damper]"
 
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