Main Rear Seal Intallation Problem?

[termin8or]

I have a persistent rear main seal leak. My mechanic is stumped. The trans was dropped and seals (trans & main were both changed.) The leak is back after just 500 miles. The crank area were the seal sits seams pretty smooth and the bearings seam tight. I thought that it could be the PVC not working but that has been recently changed. HELP. It's up in the air again waiting for yet another new part and I am starting to get the feeling that my mechanic is loosing the battle. Am I missing something here?

[92Lex]

Your mechanic is "missing something", not you. What is he/she replacing this time? How far was the seal driven in? Is the bottom end balanced?

[termin8or]

My fear is that there is excessive blow-by and that's causing an increase in the crank pressure thus blowing the seal. The seal worked fine for 200 miles then started a drip again. Mechanic said that crank surface is smooth. I wonder if there is an upgraded seal for the 4.0. No the bottom end has not been balanced. I have known the mechanic for a while so I don't think he would lie to me.

[92Lex]

Is the front crank seal also leaking? Has your mechanic checked the PCV system?

[termin8or]

No front seal leak. PVC was replaced a month ago, before this leak started. Do you know anything about that EGR vacuum modulato?

[92Lex]

What about it?

[termin8or]

Never mind. On second thought the EGR won't have anything to do with an increase in crank case pressure.