I have replaced the front crank seal 3 times on my 99 4.0 and still can not keep it from leaking. And it leaks really bad. I believe that it is the seal leaking because there is oil, drips, on the underside of the water pump but no signs of oil above that point. And of course lots of oil below that point and spread out all the way to the front fender well on the driver side. With lots of oil on the power steering fluid cooling fins below the front of the engine etc.
I replaced the harmonic balancer instead of using a repair sleeve because I have not been able to determine where the seal should set in the timing cover and the sleeve does not extend the full length of the balancer shaft. Another thing that seems to happen is as I place the balancer on the crank it seems to be pushing the seal in instead of slipping through it. I’ve oilded both the inside of the seal and the balancer shaft. This last time I set the seal in about three eights of an inch, and noticed that as the balancer went on the seal moved back.
So I’ve been thinking next time I will leave the seal flush with timing cover and let the plastic ring around the balancer seat the seal. I don’t like the idea of the plastic ring rubbing on the seal, but just don’t know what else to do? Does anybody know what that plastic ring is for or just how to do this?

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1999 Ranger 4.0 4X4 Auto XLT Air four door extend cab
145000 original miles/600 miles on rebuilt engine

Man I have had a similar problem on a rear main seal on an S10 but finally figured it out. Did you pull the timing cover off? What I had to do on the rear main seal was put a littler sealant around the outside of the seal before I drove it in. That solved my leak after pulling the tranny 4 times. The seal should be flush with the cover. Also make sure the cover does not have a crack in it.

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1999 Ranger 4.0 and extreme Snap-on tool fetish

So it appears I found the problem. The crank is not centered in the timing chain cover. This would explain why the balancer is pushing the seal in as it goes on. There was a reply in the thread about a tool for inserting the seal (good info thanks). Its called a Front Cover Aligner Set 303-093 T74P-6019-A . The name of the tool gave me the idea to measure the crank for center and sure enough it was off. I ordered the tool at http://www.shopfreedomracing.com/Fro...-A-303-093.htm. Hopefully I can get the cover back on and center it with no leaks in the oil pan to timing cover gasket!!!!!!

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1999 Ranger 4.0 4X4 Auto XLT Air four door extend cab
145000 original miles/600 miles on rebuilt engine