Valve stem seals, three choices

[dbensen]

I have an '86 with a stock 6.9 in it burning way more oil that it should. The heads were replaced with remanufactured ones about 60,000 ago. Mechanically they run well but I'm afraid (hoping) the oil could be slipping down the guides causing the high consumption. I was looking for the stem seals and it turns out there are three types. An umbrella style, a long and a short. From my research I have discovered the umbrella style goes on the exhaust valve but I have not been able to find anything on whether to use the long or the short on the intake. I did call the shop where I bought the heads and since they were remans he has no idea what was put on there when he gave them to me. I ordered all the styles so when I have everything open I can make a choice but I was hoping for some educated thoughts or real life experience on what would be best. I don't want to have to do this too often. Going to be under the hood this weekend plugging in a Moose Jr. pump, figured now is the time to start popping gaskets and fixing her up. Open to thoughts and suggestions.
Thanks, Doug

'86 F250 4x4, C6. 3.55s all stock
Sandy Spring, MD

 

[Kevin 007]

I don't have an anwer for you regarding valve seals but have you checked the CDR valve as a possible culprit for oil consumbtion? The tuna can looking thing bolted to the back of the intake manifold. If they are dirty or malfunctioning, they can let a TON of oil into the intake. With the air filter cover off, you will be able to tell with a glance if its bad or not. Everything will be damp with oil under there if the CDR valve ain't working right. Just food for thought, worth checking as it is a cheap fix if it just needs a cleaning.

I have seen or heard of some people using 7.3 valve seals on 6.9's becasuse they are tighter and don't let oil pass by. I would not go that route as "I" believe it is one of the culprits to the common 7.3 issues of early valve guide wear/failure. Again, food for thought.

Im sure someone will soon chime in with a correct answer for you.

 

[dbensen]

Thanks Kevin for the CDR cleaning thought. There is a film of oil on the intake screen so a good cleaning wouldn't hurt a thing. As far as the seals go I just ordered a set of both. Once the packages came it became clear on the application that the shorts are for the 6.9 and the longs are for the 7.3. I remember reading something somewhere that the 7.3 had premature valve guide wear due to a "better" intake seal to reduce oil consumption and emissions . That seal could be the "long" model. I think I will do the CDR cleaning and then pop the drivers side valve cover and take a look at the condition at the seals that are there. If they look good I'll probably button it back together and run it. I'll keep you posted. Thanks for the reply, Doug

 

[Kevin 007]

10-4 Doug. Good luck.

 

[Garbage_Mechan]

I don't have an anwer for you regarding valve seals but have you checked the CDR valve as a possible culprit for oil consumbtion? The tuna can looking thing bolted to the back of the intake manifold. If they are dirty or malfunctioning, they can let a TON of oil into the intake. With the air filter cover off, you will be able to tell with a glance if its bad or not. Everything will be damp with oil under there if the CDR valve ain't working right. Just food for thought, worth checking as it is a cheap fix if it just needs a cleaning.

I believe the CDR valve is treated as a big mystery and poported to do things it doesnt. Under normal operation it is no different than a tube connecting the crankcase to the intake manifold. The thing that cleaning it does is simply remove the accumulated oil and it takes a while for it to accumulate again.

The only purpose of the CDR valve is to close off the passage from intake to crankcase in the event of high vacuum caused by a plugged air filter . In this event the high intake manifold vacuum could cause oil to be drawn into the intake manifold casing a runaway. This is the only reason we have a Crankcase Depression (vacuum) Regulator is to prevent engine runaway from high intake manifold vacuum. It has nothing to do with seperating oil vapor from the blowby stream.

 

[Garbage_Mechan]

CDR Valve DOES NOT regulate oil consumtion

I believe the CDR valve is treated as a big mystery and poported to do things it doesnt. Under normal operation it is no different than a tube connecting the crankcase to the intake manifold. The thing that cleaning it does is simply remove the accumulated oil and it takes a while for it to accumulate again.

The only purpose of the CDR valve is to close off the passage from intake to crankcase in the event of high vacuum caused by a plugged air filter . In this event the high intake manifold vacuum could cause oil to be drawn into the intake manifold casing a runaway. This is the only reason we have a Crankcase Depression (vacuum) Regulator is to prevent engine runaway from high intake manifold vacuum. It has nothing to do with seperating oil vapor from the blowby stream.

Really suprised no one wanted to discuss this, it is a common misconception.

 

[TahoeTom]

This makes sense to me. I never understood the mystery tuna can. No one likes oil in their intake. I don't want to run a road draft tube (RDT) either. If you start a new thread with that title maybe there will be more discussion.