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SmallBlockMuscle

KB 6.1 Oil Leak

This has probably been discussed before but I figured I would see if anyone has any insight. I have had a nagging oil leak on my 6.1 the past couple of years and honestly I originally thought it was the rear seal so I was just living with it. I dont drive the car a ton so it's been more of just an annoying thing. Finally got some time to look at it this weekend and found the valley under the blower manifold was full of oil. My assumption is the manifold gasket is leaking so I started taking it all apart. I seem to remember this being somewhat common but would appreciate any insight. Any recommendations on better gaskets or install methods to help? Also I run a two catch can setup. First one is off the blower manifold port to a catch can and then to the spot behind the throttle body. Second is off the oil fill port to a catch can and down to the intake tube after the filter. I did find that the hoses I used off the blower manifold port were very flimsy and could have definitely been collapsing. Would that cause the gasket to fail? I don't run a PCV, should I be with this setup? It does smoke a bit on startup, probably from oil getting past the gasket and will puff a little at throttle hit.  Thanks for the help, I want to get this figured out once and for all. 

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The early KB's did this.  Mine does it.  They fixed the issue after they learned about it.

Mine leaks out the supercharger, at the rear, where the intake plenum mates with the rear of the blower.  Mine leaks the PVC system recirculated engine oil.

If you still had it together . . . you could put a paper towel between the blower and the intake manifold and see if the oil appears there.  

When I called KB about it years ago they said they reworked that area and now use a better mating surface and o-ring.  They said if I sent them my blower they would machine mine for the new surface and o-ring for free.  I have just lived with it.  I put a paper towel there when I park it and the manifold stays dry.  I bought my KB in 2011.  If yours is from about that time frame, that may be your issue.

If you have the original KB oil separator from that era - it is useless!  I did a bunch of measuring and it is completely useless.  I added a 2nd Arrington can (first generation) in-line with the KB and it helped somewhat.  Then, KB made a newer one and I bought it.  I kept the Arrington in-line.  The new KB slowed the PCV oil recycling down a lot!  I still get PCV oil in my can (and engine), but much, much, much less.

The PCV valve adds a good amount of airflow restriction to that PCV system.  Restriction = less airflow = less oil vapor making its way back into your manifold.  I've always run the PCV valve.  Many on here have completely removed the PCV system's return to any port on the engine.  I chose not to do that.  

 

 

IMG-0723.jpg

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Ps.

"Second is off the oil fill port to a catch can and down to the intake tube after the filter."

I also installed another can there.  I've never had any oil in that one.  

Rick 

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17 hours ago, rick s said:

The early KB's did this.  Mine does it.  They fixed the issue after they learned about it.

Mine leaks out the supercharger, at the rear, where the intake plenum mates with the rear of the blower.  Mine leaks the PVC system recirculated engine oil.

If you still had it together . . . you could put a paper towel between the blower and the intake manifold and see if the oil appears there.  

When I called KB about it years ago they said they reworked that area and now use a better mating surface and o-ring.  They said if I sent them my blower they would machine mine for the new surface and o-ring for free.  I have just lived with it.  I put a paper towel there when I park it and the manifold stays dry.  I bought my KB in 2011.  If yours is from about that time frame, that may be your issue.

If you have the original KB oil separator from that era - it is useless!  I did a bunch of measuring and it is completely useless.  I added a 2nd Arrington can (first generation) in-line with the KB and it helped somewhat.  Then, KB made a newer one and I bought it.  I kept the Arrington in-line.  The new KB slowed the PCV oil recycling down a lot!  I still get PCV oil in my can (and engine), but much, much, much less.

The PCV valve adds a good amount of airflow restriction to that PCV system.  Restriction = less airflow = less oil vapor making its way back into your manifold.  I've always run the PCV valve.  Many on here have completely removed the PCV system's return to any port on the engine.  I chose not to do that.  

 

 

IMG-0723.jpg

This is good info thank you. I bought the blower used so it very well could be from that era. I never thought about the back of the blower. I did pull it off and ordered a new blower seal and cometic intake gaskets from mmx. I haven't pull the intake manifold off yet so I'll see what everything looks like. I'm not using the KB catch can, its a UPR which is similar to the usual Billet tech style and I am going to put new hose on it. Still can't decide on running a PCV or not. I originally planned based on the Arrington CCV article. 

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As long as you have the blower off - I would call KB, give them the serial number, and ask them about.  If it needs their fix, I would have them do it.  

I would hate to see you put it all back together and find that you still have the same problem.  

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20 hours ago, rick s said:

As long as you have the blower off - I would call KB, give them the serial number, and ask them about.  If it needs their fix, I would have them do it.  

I would hate to see you put it all back together and find that you still have the same problem.  

I will definitely give them a call with the serial number. My original thought was the amount of oil that leaks couldn't be going through the blower but maybe. Doesn't hurt to check 

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