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04-15-2018, 09:47 PM
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#1
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Veteran Member
City: Boston
Country: US
Vessel Name: Rose Mary
Vessel Model: 42 Grand Banks Motoryacht - 1985
Join Date: Feb 2017
Posts: 55
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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?
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04-15-2018, 11:14 PM
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#2
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Senior Member
City: hawaii
Country: usa
Vessel Name: #31
Vessel Model: ex-Navy MUB 50 fish/cruise
Join Date: Aug 2013
Posts: 370
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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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You can lead a horse to water,
But you can't make him ski...
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04-16-2018, 05:43 AM
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#3
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Guru
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 16,832
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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?
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04-16-2018, 06:12 AM
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#4
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Guru
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 4,124
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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.
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04-16-2018, 06:19 AM
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#5
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Guru
Join Date: Jan 2010
Posts: 763
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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
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04-16-2018, 06:19 AM
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#6
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Member
City: Leland, NC
Country: USA
Vessel Model: Still looking
Join Date: Jan 2015
Posts: 13
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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.
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04-16-2018, 06:43 AM
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#7
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Member
City: Goldcoast
Country: Australia
Vessel Name: Moana
Vessel Model: 1996 M40 Riviera aft cab
Join Date: Jun 2014
Posts: 23
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Last harmonic balancer I replaced could only be removed by using a rattle gun. Replace the same way.
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04-16-2018, 07:06 AM
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#8
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Guru
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 16,832
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Based on engine rotation, opposite tighten/loosen?
Just using compression to counter act based on the sledge or rattle gun need?
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04-16-2018, 07:12 AM
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#9
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Veteran Member
City: Boston
Country: US
Vessel Name: Rose Mary
Vessel Model: 42 Grand Banks Motoryacht - 1985
Join Date: Feb 2017
Posts: 55
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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.
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04-16-2018, 07:13 AM
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#10
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Member
City: Goldcoast
Country: Australia
Vessel Name: Moana
Vessel Model: 1996 M40 Riviera aft cab
Join Date: Jun 2014
Posts: 23
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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.
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04-16-2018, 07:14 AM
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#11
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Veteran Member
City: Boston
Country: US
Vessel Name: Rose Mary
Vessel Model: 42 Grand Banks Motoryacht - 1985
Join Date: Feb 2017
Posts: 55
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Quote:
Originally Posted by kapnd
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.
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04-16-2018, 07:23 AM
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#12
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Enigma
City: Slicker?
Country: Bumpkin?
Join Date: Oct 2007
Posts: 10,408
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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.
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RTF
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04-16-2018, 09:40 AM
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#13
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Guru
City: Aventura FL
Country: USA
Vessel Name: Kinja
Vessel Model: American Tug 34 #116
Join Date: Oct 2017
Posts: 1,460
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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?
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No longer do I waste time reading the news.
Way too much to learn here.
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04-16-2018, 09:43 AM
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#14
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Guru
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 16,832
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Sonds like the retention bolt is still righty tighty then if you check with a normal torque wrench.
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04-16-2018, 11:49 AM
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#15
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Senior Member
City: Anacortes Wa.
Country: usa
Vessel Name: Sea Fever
Vessel Model: Defever 49 RPH
Join Date: Sep 2012
Posts: 350
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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.
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04-16-2018, 12:03 PM
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#16
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Guru
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 16,832
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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.
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04-16-2018, 12:09 PM
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#17
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Guru
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 4,124
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Pretty sure the big bolt is standard thread.
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04-16-2018, 12:12 PM
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#18
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Veteran Member
City: Boston
Country: US
Vessel Name: Rose Mary
Vessel Model: 42 Grand Banks Motoryacht - 1985
Join Date: Feb 2017
Posts: 55
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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.
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04-16-2018, 06:28 PM
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#19
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Veteran Member
City: Channel islands ca
Country: Usa
Vessel Name: Lillie Ruth
Vessel Model: 78 Grand banks 36 classic
Join Date: Apr 2012
Posts: 33
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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
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04-16-2018, 07:01 PM
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#20
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Guru
City: Cape May, NJ and Englewood, FL
Country: USA
Vessel Name: Irish Lady
Join Date: Dec 2007
Posts: 1,853
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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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Archie
1984 Monk 36 Hull #46
Englewood, FL and Cape May, NJ
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