Harmonic balancer slipping on Lehman

I have a twin engine, and on the starboard side I can grab the outside of the crankshaft pulley and slide it around the crankshaft bolt. Does this mean it's broken, or is this normal? I know for cars when your harmonic balancer slips, you need a new one. The port engine does not seem to do this, and the starboard side is also a bit wobbly. The center of the pulley pulley is not loose (the bolt is rock solid), just the outer part, indicating the rubber is cashed. These are Ford Lehman 135s.

Does this need to be replaced, if so, any good ideas on how to remove the bolt? I tried cranking on it - no dice. Also tried cranking the starter for an instant with a wrench on it, no dice... (as a side note, I drained all the oil from the engine, is there any problem with trying this again, or is it bad to crank it once or twice without oil? I don't want to refill, because I might replace the crankshaft seal in the timing cover if I have to pull the pulley)

Also, I almost always follow the rule that if something goes bad on one engine, replace it on the other, but $400 just for the part.... What do you guys think, will the 35-year-old rubber be kaput on the port-side engine too?

The harmonic balancer plays a very important role, I’ve seen broken crankshafts in cases when a bad balancer was ignored.
I would replace it immediately.
Make sure that the engine is running perfectly, a weak cylinder can contribute to the wear on the balancers rubber.

I am thinking of replacing mine as it was once mentioned the lifespan was only 2500 hrs.

While that seems low, I may go ahead as I am now over 3000.

So I roo am curious, any tips or tricks to that replacement?

Sometimes a "slugging wrench" or big closed end industrial wrench hit with a 2lb hammer will get the big bolt.

One trick on checking the damper rubber ring is to sharpie mark across it and if the marks move relative to each other, rubber is slipping. If rubber is not slipping or otherwise deteriorated, probably ok.

I had to replace the dampener on my 120. The new design is different than the old as it does not have the rubber Hub. Honestly look just like a solid pully. There is a place that can rebuild your current one if you would rather that

Rebuild?

There is a company in Redding, Ca. which rebuilds them for much less$ Damper Doctor. No affiliation, you can request a quote on their web site.

Last harmonic balancer I replaced could only be removed by using a rattle gun. Replace the same way.

Based on engine rotation, opposite tighten/loosen?

Just using compression to counter act based on the sledge or rattle gun need?

Holy crap! I had no idea they could be rebuilt - that's amazing. Email sent. Now to remove them beasts. I guess I'll probably have to head to home depot and pick up an impact wrench and harmonic balancer puller.

Yes engine compression should be enough when using rattle gun, taking it off and putting back on. You may consider checking with torque wrench when finished, check with engine torque specs as they are quite high settings, you will probably need to lock the motor to stop it turning when using torque wrench.

kapnd said:

The harmonic balancer plays a very important role, I’ve seen broken crankshafts in cases when a bad balancer was ignored.
I would replace it immediately.
Make sure that the engine is running perfectly, a weak cylinder can contribute to the wear on the balancers rubber.

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Question, what do you mean by a 'weak cylinder' and how would this be diagnosed? The girls have 4500 hours, and they seem to run great.

Greetings,
Mr. W. IF you are going to purchase a "rattle gun" rather than rent one for this one time job, I would suggest you check out the prices at Harbor Freight compared to HD.

Maybe I give up too easily. I would start by calling a tech. There may be other problems in involved.

At the very least, call a tech, get a diagnoses and an estimate.
Chances are, he will complete the job much faster than you.

Do you want to spend your time rebuilding or cruising?

Sonds like the retention bolt is still righty tighty then if you check with a normal torque wrench.

You may be able to rent a electric impact gun. That would save you needing to bring a air compressor to the boat. Not sure about theses engines turning opposite directions. I believe that is handled via the transmissions. Check with American Diesel.

I think tbey all turn the same way, left hand, but on the balancer side of the engine you would expect a bolt to tighten the opposite way of rotation for security sake.

Pretty sure the big bolt is standard thread.

Just got the bolt off. Starter motor and breaker bar. The trick was to have the end of the breaker bar in the air, about a foot off the engine support stringer. When the starter motor fired, the bar slammed into the engine support and the bolt freed. Checked out impact drivers but there's not enough clearance between the front of the engine and the bulkhead. Now for the balancer puller, the one I got from autozone is too small... Nothing is ever easy on the boat.

crankshaft pulley

The hard part will be reinstalling and torquing the bolt. Probably will need to remove the starter motor and jam the flywheel with a crowbar. 2 man job. And you need a big wrench - 240 ft lb.

Dan

Slightly off topic for SKI. Do you need to do similar for Perkins 6.354? I could not find anything in the manuals.

High Wire said:

Slightly off topic for SKI. Do you need to do similar for Perkins 6.354? I could not find anything in the manuals.

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I think most Perkins use a viscous damper, which tends to be more reliable than the rubber bonded ones. If you can post a pic, I can tell which it is.

Westiculo said:

...The trick was to have the end of the breaker bar in the air, about a foot off the engine support stringer. When the starter motor fired, the bar slammed into the engine support and the bolt freed...

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I’ve been following this thread, we also have a SP 135. Wes, “you’re better man than I am, Gunga Din”! I have heard about doing something similar but you are the first. Holy ****!!! By the way, congrats on getting the bolt loose.

Ski in NC said:

I think most Perkins use a viscous damper, which tends to be more reliable than the rubber bonded ones. If you can post a pic, I can tell which it is.

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I found a DAMPER on the parts list #32 but nothing in the service manual about replacement.

I didn't see anything in my manual about the balancer (though it might be in there), I just noticed the crankshaft pulley was wobbly and apparently it definitely needed replacement. If your engines are over 30 years old, I wouldn't be surprised if yours are shot too; what kind of rubber really lasts that long? Mark the inner and outer ring and see if they're slipping. I could make mine slip by hand...

I was also worried about the installation; called Brian at American Diesel and he said that was the easy part, just tighten it up - looks like there's a few ways to keep the crankshaft pulley from spinning while you do it.

Ended up sending the balancers to Dale at Dale Manufacturing. The guy responded to my email immediately, is very nice, and enthusiastic. He's done a few different Lehman pulleys before. He is charging $130 per, for appx 8-inch pulleys. USPS flat rate shipping, and I should have them back next week. Pretty pumped you guys told be about rebuilding them.

The bolt is standard, right handed thread. Don't think it matters which way it tightens since it's so freakin tight; also, the pulley is keyed. Word is, don't scratch the oil sealing ring. Also ordered new seals from American Diesel even though mine weren't leaking - I hope to never do this again so am making sure my ass is covered.

Proof!
You can tell I've been doing engine maintenance by the bruised thumbnail.
The seals look easy to pry out (indicated by the blue arrow) though I haven't tried yet.
My auto-sized balancer puller was too small for the job, so I had to 'adapt' it with a bunch of other hardware lying around the boat.

Westiculo said:

Question, what do you mean by a 'weak cylinder' and how would this be diagnosed? The girls have 4500 hours, and they seem to run great.

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Quick check is to loosen each injectors HP fuel feed line, one at a time, while the engine idles. It should slow the rpm and cause the motor to run rough.
If loosing a particular injectors fuel line has no effect, that cylinder has a problem, then all you have to do is figure out what that might be!