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Play in crankshaft pulley

Posted by Bill Greenwood

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Play in crankshaft pulley #1
Bill Greenwood Gahanna, OHIO, USA 1969 MG MGC GT 1972 MG MGB GT	Posted: May 20, 2012 06:41PM Registered: 4 years ago Posts: 241

I have about 1/8" play in the crankshaft pulley. The large nut does not move but I
noticed there are about 3/8" of exposed threads showing on the nut. Also I have another pulley wheel bolted to the outside of the harmonic balancer that does not appear to do anything except reduce the distance the big nut screws on to the shaft. Anyone have pic they could post?
Thanks Bill.

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Re: Play in crankshaft pulley #2
Bill Greenwood Gahanna, OHIO, USA 1969 MG MGC GT 1972 MG MGB GT	Posted: May 20, 2012 08:20PM Registered: 4 years ago Posts: 241

Pic of mine that might help to explain what my problem is.

Bill.

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2012-05-20 18.54.50.jpg (33 KB) –

Re: Play in crankshaft pulley #3
coloradomgc William Panos Colorado Springs, USA 1969 MG MGB 1969 MG MGC GT	Posted: May 20, 2012 09:00PM Registered: 5 years ago Posts: 195

Hi Bill,
I don't have a picture handy, but the front pulley is for the air pump. If your emissions system has been removed you can take out the four bolts and that pulley will come right off. With the pulley off you'll have better access to the nut. There is usually a locking tab washer that keeps the nut from coming loose. That might explain why you can't tighten the nut any further. Doesn't explain why your damper is loose in the first place.
Bill P.

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Re: Play in crankshaft pulley #4
kirks-auto robert kirk Davenport, Iowa, Rock Island, Illinois, Clearwater, USA	Posted: May 21, 2012 06:13AM Registered: 4 years ago Posts: 13,091

Bill
I hope William has sorted this...
I've had good luck having the harmonic balances rebuilt. If you are handy or know someone who is, I can get you a new unit capable of 12000 rpm...probably not good to test that claim on a stock engine.... smileys with beer

Regards,
Robert Kirk
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Re: Play in crankshaft pulley #5
Restoman Dana R amston, connecticut, USA 1959 MG MGA 1500 1967 Jaguar E-Type Coupe 1968 MG MGC GT 1969 MG MGC	Posted: May 21, 2012 08:19AM Registered: 2 years ago Posts: 333

Bill, all that I've seen have the threads exposed in the nut. Make sure the crank sprocket has the shims behind it, and the slinger installed, and as Bill sez the tabwasher. If these parts are missing then there could be the .125 you need.

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Re: Play in crankshaft pulley #6
Bill Greenwood Gahanna, OHIO, USA 1969 MG MGC GT 1972 MG MGB GT	Posted: May 21, 2012 11:24AM Registered: 4 years ago Posts: 241

Just to clarify, the 1/8" play is on the circumference of the pulley (not in/out movement) & the nut does not move at all.

I'll get the radiator removed then remove the pulley that's not needed & see what we've got.

Engine is recently making a noise like a rod bearing rumble so I'm hoping its just the pulley.

Thanks for the responses.

Bill.

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Re: Play in crankshaft pulley #7
kirks-auto robert kirk Davenport, Iowa, Rock Island, Illinois, Clearwater, USA	Posted: May 21, 2012 11:54AM Registered: 4 years ago Posts: 13,091

The pulley has a woodruff key. There "should" be zero rotational wobble/movement on the crank.
The rubber in the dampener, coming apart, could give rotational or lateral movement..that is what I suspect.

Regards,
Robert Kirk
kirkbrit@yahoo.com
563 323 1017
Moss distributor UK importer
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Re: Play in crankshaft pulley #8
Bill Greenwood Gahanna, OHIO, USA 1969 MG MGC GT 1972 MG MGB GT	Posted: May 21, 2012 12:05PM Registered: 4 years ago Posts: 241

Robert,

Suspect your suspicions are correct.
I will report the outcome in a day or so.

Thanks, Bill.

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Re: Play in crankshaft pulley #9
mhirsch13 Mike Hirschman Maple Grove, Minnesota, USA 1969 MG MGC GT	Posted: May 21, 2012 02:22PM Registered: 5 years ago Posts: 85

Bill,
If you remove the small pulley that runs the air pump from the harmonic balancer, as you mentioned you intended to do, be carefull with it. That small pulley chips rather easily, and a good pulley is hard to find. Mike

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Re: Play in crankshaft pulley #10
kirks-auto robert kirk Davenport, Iowa, Rock Island, Illinois, Clearwater, USA	Posted: May 21, 2012 03:08PM Registered: 4 years ago Posts: 13,091

In reply to # 2073436 by mhirsch13 ...and a good pulley is hard to find. Mike

Or near impossible...

Regards,
Robert Kirk
kirkbrit@yahoo.com
563 323 1017
Moss distributor UK importer
Beat or match any retail/delivered quote

How to advertise on this website

Kirk's Auto Parts for your classic British and Italian car. 30 years in business.

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Re: Play in crankshaft pulley #11
Bill Greenwood Gahanna, OHIO, USA 1969 MG MGC GT 1972 MG MGB GT	Posted: May 22, 2012 07:18PM Registered: 4 years ago Posts: 241

Well, it turned out to be nothing more than a loose harmonic balancer. Tightened it up & the engine noise went away. I feel like I dodged a bullet.
Bill.

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Re: Play in crankshaft pulley #12
Swamperca Swamper CA Nor Cal, USA 1969 MG MGB GT "Rat" 1969 MG MGC GT "A 69 MGC" 1970 MG MGB GT "Widow" 1971 MG MGB "Ruby" 1974 MG MGB "Groovy B"	Posted: May 22, 2012 09:43PM Registered: 8 years ago Posts: 7,659

In reply to # 2074704 by Bill Greenwood Well, it turned out to be nothing more than a loose harmonic balancer. Tightened it up & the engine noise went away. I feel like I dodged a bullet.
Bill.

WOW, you got very lucky.

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Re: Play in crankshaft pulley #13
Big6Mark Mark Miller Springfield, OR, USA 1960 Austin-Healey 3000 1968 MG MGC "Red Tail" 1968 MG MGC 1968 MG MGC GT "The Wreck" 1969 MG MGC GT "The Lump"	Posted: May 25, 2012 11:39AM Registered: 5 years ago Posts: 1,220

Bill:

If there is any play in the rotational direction at the harmonic damper it is because the nut is loose, however that also means that the damper/pulley assembly has been able to rotate a bit on the crank.

That rotaional movement will also damage the Woodruff key. This means you should remove the pulley and replace the key. If not, you can expect to have to do it again. Luckily the key is softer than either the crank or the pulley so any damage is limited to the key, but it needs to be replaced.

This is a common enough of a problem as I had this happen on my Healey Mk III and I think Steve had it happen on his GTS replica. When it started on the Healey it sounded almost like a loose rod bearing.

Sorry to have not gotten around to making a comment before this.

C Ya,
Mark

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