Hi There,

i discovered an oil leak on my last run from the front left side of my engine, much more of a splash only whilst i was WOT.

since it was the other side of the oil cooler and seems to be splashing onto my fuel filter i figure it might have been from the crank oil seal.


after removing the damper to change the oil seal, i noticed that the part of the damper which fits into the oil seal seems a bit rough, so i guessed i should get a new one installed "since i believe was the reason of the oil seal to leak oil on high rpm"

now! my local dealer does not have a damper available, however i managed to get hold of a damper 3963532 number embossed on the back of it, seems to be the right one however has a different number to my previous one
# 10216339.

has anyone used same damper ( 3963532 ) on a 502 mercruiser before? should it be OK?

please help!

3963532 is for a mark 4 454.10216339 is for a gen 5&gen6 454/502,they are different due to the difference in the back of the crankshaft.i would not interchange them.

They seem really the same, weight distribution and diameter.
Should I not fit it?

If I remember correctly the gen 6 and mark 4 have a slightly different external balance to them. If your balancing your crank either will work, If your just bolting it on use the correct one.

I purchased new aftermarket harmonic balancers, to replace my GM/Merc external balanced units. I brought them to a shop that specializes in balancing, and had them weight matched.

The only available harmonic balancer I found is the 3963532.

Can I use it? What if I do? Any damage?

http://www.gmpartsdirect.com/oe-gm/10216339

i just ordered a gen6 block from them thursday.7 to 10 day delivery,no tax,free shipping.same price as summit but they wanted 111 bucks for shipping.

My balancer balancing .

I had a buddy order a pair of GM perf 502 partial engines from them. Fast shipping , and free shipping, and good price. Pretty sure it was from them. Ill have to double check to be sure