470 Harmonic Balancer issue

[Sundodger]

I am in most of the way through installing an alternator conversion from Hun-Finn on a 1977 Glasply with a Mercrusier 470 and ran into an issue reinstalling the harmonic balancer.

When I install the balancer it doesn?t ever fully seat against the crankshaft, it actually will keep getting pressed on until the outside ring of the balancer contacts the front engine cover. As you can imagine, that will not work.

I am considering machining the outer edge of balancer so it doesn?t contact the front cover or installing a spacer behind the balancer on the snout of the crank.
From my crude measurements I need about 0.30? to solve my issue.


Does anyone have any idea what?s going on here? The exploded diagrams I have reviewed don?t seem to have anything I am obviously missing (a spacer or something).

 

[stonyloam]

Re: 470 Harmonic Balancer issue

It sounds like the cover might have been slightly distorted when you bolted the kit on. If that is the case I am not sure I would fool around with the rather fragile cover (they can crack rather easily) and risk damaging it, the spacer might be the best way to go. Be careful when you put the belt on, it may change things again. Good luck.

 

[Sundodger]

Re: 470 Harmonic Balancer issue

Thank you for the response.

It doesn?t appear to be bent (the clearance between the front cover doesn?t change significantly as the engine is turned over).

One thing that I just put together (sad, I know), when I removed the balancer I noticed that there was VERY little breakaway tq required to loosen the crank bolt. I was very surprised by this given it is an old crusty boat that has spent a good amount of time in salt water. There was red locktight on the bolt threads.

This makes me think it could be a previous issue, and the last person to mess with this didn?t seat it all the way (for the clearance reasons) and chose to use Loctite to attempt to keep the bolt from backing out.

That is a scary thought given this boat has been in my family since the early 90?s and has spent a lot of time on the water fishing. I am almost positive no one since we owned it has taken the balancer off (I just sent a message to my father to confirm).
Obviously having effectively zero tensile load in the bolt and using a chemical thread locker violates all the best practices procedures in existence for bolted joints. But even though there is very little axial load on that joint, I am impressed it held together if this is the case.

Could this mean that the balancer I have is incorrect?

Does anyone have 470 balancer part numbers and interchange that can help me identify if this is the issue?

 

[Eric 3.7LX Alpha 1]

Re: 470 Harmonic Balancer issue

I guess the question is where is the stop suppose to be? Should it be on the balancer or the crank?

Something's definately not right. Maybe someone else with a 470 has one off, and can look for you.

The keyway slot on the balancer is all the way thru to the front?

 

[Sundodger]

Re: 470 Harmonic Balancer issue

I guess the question is where is the stop suppose to be? Should it be on the balancer or the crank?

Something's definately not right. Maybe someone else with a 470 has one off, and can look for you.

The keyway slot on the balancer is all the way thru to the front?

That is a very good point.

I was assuming that the back of the snout on the balancer seated against the first step in the crankshaft to form a hard joint, but maybe that is not true?

I will double check when I get home, but I am 95% sure that the keyway slot is all the way though the balancer.

If anyone knows for sure how this joint comes together, please post up. None of the manuals I have looked though show this very well.

 

[Sharp Shooter]

Re: 470 Harmonic Balancer issue

The outer ring of a balancer is rubber mounted to the innner hub of the balancer. Over time it's not uncommon for the outer ring to rotate because the rubber will eventually wear out. This often causes a vibration. In your case, maybe the outer ring has moved closer to the cover. You should be able to see it if this is the case. Just take a close look at the balancer looking at the outer ring in relation to the center or hub of the dampner.

Just a thought...

 

[guyaverage]

Re: 470 Harmonic Balancer issue

Go to the Breezeworks 470 forum and search on "Alternator rotor rubs front cover", there is a thread there about this. The thread dies without the original poster saying what the problem ended up being, but it gives some helpfull suggestions. I would post a link to the thread but I wasnt sure if that was permitted.

 

[Sundodger]

Re: 470 Harmonic Balancer issue

Go to the Breezeworks 470 forum and search on "Alternator rotor rubs front cover", there is a thread there about this. The thread dies without the original poster saying what the problem ended up being, but it gives some helpfull suggestions. I would post a link to the thread but I wasnt sure if that was permitted.

Thank you!

 

[Sundodger]

Re: 470 Harmonic Balancer issue

The outer ring of a balancer is rubber mounted to the innner hub of the balancer. Over time it's not uncommon for the outer ring to rotate because the rubber will eventually wear out. This often causes a vibration. In your case, maybe the outer ring has moved closer to the cover. You should be able to see it if this is the case. Just take a close look at the balancer looking at the outer ring in relation to the center or hub of the dampner.
Just a thought...

One thing I found odd, this harmonic balancer doesn?t seem to have any rubber in it. It seems to just be a single piece of cast ferrous metal (other than the magnets which I removed).

Go to the Breezeworks 470 forum and search on "Alternator rotor rubs front cover", there is a thread there about this. The thread dies without the original poster saying what the problem ended up being, but it gives some helpfull suggestions. I would post a link to the thread but I wasnt sure if that was permitted.

I just finished reading that thread, and I don?t think the issues they recommend investigating apply to me.
I did check (admittedly not a precisely) on crankshaft endplay and didn?t find anything that should cause this and I never removed the front cover.

Other thoughts?

 

[Eric 3.7LX Alpha 1]

Re: 470 Harmonic Balancer issue

I found a balancer for sale on ebay:
http://cgi.ebay.com/ebaymotors/Mercruiser-470-3-7-170-Harmonic-Balancer-Late-style-/130507543928

advertising as a "late style" not sure if there were ever changed or not, or what late style was referring to in the ad.

Looking at the one above, it appears that the stop would be built in on the crank. Wonder if at some time a magnet issue caused it to be replaced with a wrong one? That's saying that there was more than one spec on them for different years.

 

[Sharp Shooter]

Re: 470 Harmonic Balancer issue

One thing I found odd, this harmonic balancer doesn?t seem to have any rubber in it. It seems to just be a single piece of cast ferrous metal (other than the magnets which I removed).

It doesn't look like this?

Some are fluid filled....

 

[Sharp Shooter]

Re: 470 Harmonic Balancer issue

I found a balancer for sale on ebay:
http://cgi.ebay.com/ebaymotors/Mercruiser-470-3-7-170-Harmonic-Balancer-Late-style-/130507543928

advertising as a "late style" not sure if there were ever changed or not, or what late style was referring to in the ad.

I can see the rubber in that one...

 

[Eric 3.7LX Alpha 1]

Re: 470 Harmonic Balancer issue

It doesn't look like this?

Some are fluid filled....

The 470 is a whole nother beast. The balancer has magnets inside of it which are part of the charging system. They don't use a alternator, they have a stator inside of the "balancer" which when the magnets spin create current.

It is not like a regular balancer on any other engine.

 

[Don S]

Re: 470 Harmonic Balancer issue

Guys, the 470's don't have harmonic balancers, they have a rotor, Metal hub with magnets inside and a pulley cast on the outside. No rubber in them at all.

EDIT: Eric was posting while I was typing .......... and talking on the phone.

 

[fmalott]

Re: 470 Harmonic Balancer issue

i converted my 83 470 i left everything on my old voltage regulator and the rotor just because i was afraid of what you been saying lesson learnt

 

[Don S]

Re: 470 Harmonic Balancer issue

i converted my 83 470 i left everything on my old voltage regulator and the rotor just because i was afraid of what you been saying lesson learnt

The rotor does not touch the stator in any way, shape, or form. The rotor magnets rotate around the stator, no way could they touch so it has. The reason for removing the stator is to prevent damage if the magnets come loose ............... and they do.

 

[Sundodger]

Re: 470 Harmonic Balancer issue

I found a balancer for sale on ebay:
http://cgi.ebay.com/ebaymotors/Mercruiser-470-3-7-170-Harmonic-Balancer-Late-style-/130507543928

advertising as a "late style" not sure if there were ever changed or not, or what late style was referring to in the ad.

Looking at the one above, it appears that the stop would be built in on the crank. Wonder if at some time a magnet issue caused it to be replaced with a wrong one? That's saying that there was more than one spec on them for different years.

Hmmm?

That is interesting, I need to figure out the differences between the different balancers available for a 470. It is quite possible that a previous owner/mechanic installing the wrong one.

Does anyone have any recommendations where to find such information?

The rotor does not touch the stator in any way, shape, or form. The rotor magnets rotate around the stator, no way could they touch so it has. The reason for removing the stator is to prevent damage if the magnets come loose ............... and they do.

This is my reason for removing the stator and magnets.

 

[fmalott]

Re: 470 Harmonic Balancer issue

i have ask this question before some permantly remove stator and rotor to lessen the wieght of the motor and of coarse what Don S said and yes it will happen so maybe down the road i will permantly remove stator and rotor since i converted to alternator, so we don't need them unless there is someone out there says different

 

[stonyloam]

Re: 470 Harmonic Balancer issue

OK if you have magnets inside the rotor, they are all the same, no old or new same part number, so that is not it. On mine the rotor cones to a stop when the center contacts the end of the crankshaft. The center bolt is supposed to be torqued to 75 ft lb. obviously yours was not. I think your best option is a shim just thick enough to give you clearance and torque er down. The other possibility is that someone had the cover off and used a too thick gasket when they replaced it. You need the rotor for the pulley, so leave it intact. I removed the stator, and left the magnets in the rotor. Lots of misinformation here (except from Don of course). Good luck.

 

[Sundodger]

Re: 470 Harmonic Balancer issue

i have ask this question before some permantly remove stator and rotor to lessen the wieght of the motor and of coarse what Don S said and yes it will happen so maybe down the road i will permantly remove stator and rotor since i converted to alternator, so we don't need them unless there is someone out there says different

I am not sure what you are asking, can you please rephrase that?

OK if you have magnets inside the rotor, they are all the same, no old or new same part number, so that is not it. On mine the rotor cones to a stop when the center contacts the end of the crankshaft. The center bolt is supposed to be torqued to 75 ft lb. obviously yours was not. I think your best option is a shim just thick enough to give you clearance and torque er down. The other possibility is that someone had the cover off and used a too thick gasket when they replaced it. You need the rotor for the pulley, so leave it intact. I removed the stator, and left the magnets in the rotor. Lots of misinformation here (except from Don of course). Good luck.

Thank you for the very valuable information about balancer/rotor interchange. I am going attempt to space it out a bit, and let everyone know how it goes. If I have to space it too far out and the belt alignment starts suffering, I might have a bit machined off of the balancer/rotor.