prb51 said:
Is it the original scroll seal that leaks so regularly or the bearing block beneath with the felt packing?
I believe it's the scroll seal; for several reasons :
1) Many rebuilders don't replace it at all, or don't set the clearances properly when installing a new one.
2) The dimensions shown in the book for the mandrel to set the clearances are apparently wrong. Reportedly the mandrel sold by some vendors is even worse wrong than the book.
3) Later TR4/A engines had "PCV" setups that were ineffective and allowed the buildup of crankcase pressure during WOT operation. The scroll seal is ineffective at holding back pressure.
4) The felt packing is still required even with the 'uprated' seal.
BTW, the tractor version of this engine actually did use a lip-type seal. Like similar seals of the day, it was relatively short-lived ... the scroll seal was an improvement!
Also BTW, I've always used Permatex #3 on the felt; and never seen any signs of oil leakage through it. Having a tiny bit or Permatex seep through the seam is an indication to me that there is enough inside; it won't hurt anything.