Thread: 3.9 v8 crankshaft pulley

I would love to tell you it's not a crankshaft issue, but.
These cranks are very strong, unlikely it is bent or such.
First thing I would do is;

1. Is the center Bolt that holds it on, tight? , has the whole thing become loose?
If so, then movement may have worn the key way in the crankshaft. If loose, remove the bolt
and clean/check it, these are stretch bolts, (about 24mm ) refit using blue locktite, if wobble has gone, leave it,
if wobble still there, remove, before locktite does it's thing.

2. The pulley is actually a vibration damper, inner and outer parts bolted together with 6 bolts. you can see or feel these from the front inside the rim.
I've never seen one fail as such, but it's known that the material in between can separate and the locating tabs break, (corrosion) causing the outer section to slip
and throw the timing marks out. If this material breaks down completely, it can cause the outer rim to wobble, again, I've never seen this.

3. Can you check if it's just the outer rim that is wobbling, and not the inner center one, an obvious sign here would be if the front timing cover oil seal is leaking badly.
that tells you it's the inner one as well and that's not good.

You are looking at at least replacing the pulley and while off, check the key way for wear and replacing front timing cover seal.
or simply a case of tightening the bolt.
hope this helps..

seal.jpgharmonic.jpg

Many many thanks Ronski, I went on in.... the bolt was every bit of the 200ft/lbs to remove. The whole assembly had the wobbles.

So here's the oil seal, pretty respectable for 24 years, without much muck/ leak - I will replace anyway.

The offending unit is the harmonic balancer, which particularly on the other side has cracks in the rubber, so I will replace. Everything else seems pretty schmick, phwew! After all these years of mechanicing I truly shouldn't default to the worst case but cant help it - then again I guess I am happy when it winds back from there and turns out to be maybe $300 not $3000. Thanks again appreciate your time - I am new to this engine set up so every help is massive, have a great Christmas.

Your welcome, a trick I use to clean around front seal, is to roll up some stiff cardboard into a tube, place over crank end and release.
It then expands to the seal lip and 'usually' prevents dirt and muck getting into engine when cleaning before fitting new seal.
You may have your own method,
merry Xmas.

Its common for these older rubber bonded balancers to de-laminate then separate. I once got about 200m from home when i lost all electrics and power steering, pulled off the road to inspect and found i had lost the crank bolt and the balancer was just hanging by the belts (81 RRC so had 3 ). Walked home and took the bolt off a P76 4.4 i have in the shed, remounted and torqued the bolt and carried on to work - only about an hr total for a roadside fix.