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Ask Jeff Policky Your Own Question
Jeff Policky
Jeff Policky, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 2425
Experience:  Yamaha Gold, Suzuki Gold, Honda Bronze, Polaris Bronze, BRP
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My 2006 Harley fat boy 88b engine with 15k miles on it blew

Customer Question

my 2006 Harley fat boy 88b engine with 15k miles on it blew out the seal between the oil filter and the flange that it screws on to. I replaced the filter with a new one that i had which had been sitting for about 2 years and it blew that seal also. therefore I replaced it with a new one from Harley Davidson dealer and you guessed it. the same thing happened again. I have changed the oil on this bike before as well as many others. I hand tighten the oil filter and then add 1/4 turn more according to the manufacturers directions. Yes I apply a thin film of oil to the rubber gasket on the oil filter before installing it. have you ever heard of this problem before?
Submitted: 2 years ago.
Category: Motorcycle
Expert:  P.J. replied 2 years ago.
I've never heard of this on any twin cam since they've been around since '99. Are there any other odd issues going on like oil not returning to the tank, valve train noise, or excess oil showing up in the air cleaner. It would seem that there has to be a restriction somewhere or problem in the relief system. The first check would certainly be the oil pressure with a gauge. Thanks, P.J.
Customer: replied 2 years ago.
well oil is returning to the tank or else i would have had oil build up in the rocker area. no valve train noise at all. no oil in the air cleaner. restrictions are what I thought of but where? if the problem was in the supply side I would have got an oil light condition. I am concerned about the tightening of the oil filter however as this has been brought up by a few other mechanics. what are your recommendations for the tightening procedure? does it change as the bike gets older? by the way this happens at idle with the enrichener pulled out to full when oil pressure should be at its lowest. it also happened without the enrichener pulled out at all. again this should have been at a low oil pressure situation too.
Expert:  P.J. replied 2 years ago.
Tightening the oil filter is just spin it on until the gasket touches and it stops with little to no effort applied. Then 1/2 to 3/4 turn. I go just good and hand tight which usually ends up somewhere in the 3/4 to 1 turn. In 12 years I've never had an issue. You wouldn't have oil buildup in the rocker area but you would have in the sump if the scavenge side wasn't working properly. Twin cam oil flow is kinda strange as the oil exits the filter then returns to the top end before gravity sends it down the pushrod tubes to the sump. There is a top end screen behind the cam plate in the cam chest that can become blocked if debris makes it to it. This could cause an issue. I would think you would get a very noisy valvetrain if that was the case though.