Question about engines in General.

[biggs85]

Ok I was just thinking about this today on the way home from my Grandparents house. As you can see in the picture I've circled the valve stems. I was wondering if there were ever any problems with engines leaking oil where the valve stems have to come through the cylinder head. It seems like you would have oil leaking through on both the exhaust and intake valves. I don't know if this isn't a problem at all or if it can be and I've just never heard about it.
Thanks and Merry Christmas!

 

[Texan01]

Yes any engine can leak oil through the valve stems if the seal is bad and there is enough oil to seep past the stems. usually the symptoms are a cloud of blue smoke on startup and a blue cloud after prolonged idle.

 

[biggs85]

How does it seal though? It seems like it's just metal to metal.

 

[BradE.]

The valve stems have rubber seals, as they degrade over the years, you can get oil past them causing, as Texan said, blue smoke at idle.

 

[jsun]

Originally posted by Texan01
Yes any engine can leak oil through the valve stems if the seal is bad and there is enough oil to seep past the stems. usually the symptoms are a cloud of blue smoke on startup and a blue cloud after prolonged idle.

Correction... Bad valve seals will aid in more of a greyish colored smoke rather then blue.

But yes exteded idle will show signs of worn valve stem seals. For instance, Idle at a red light for some time, take of...cloud of grey smoke. Then gone until your next extended idle.

j

 

[dogfriend]

I've owned a couple of engines that leaked past the valve guide seals. Its fairly common.

I once owned a Toyota Pickup which left behind clouds of smoke when idling - I was going to replace the valve guide seals when I discovered that it had a broken valve guide on one of the exhaust valves.

 

[Charlie's_93EB]

I have been told by my dad that I have bad valve seals.
He is boat mechanic, and says it would be something like 10 to 14 hours to replace them all.
But anyway I am going to take my truck to my car mechanic anyway because the 4X4 and OD do not work, and there is a large CLUNK when I hit any bump.

I have read my Haynes and it looks ez but I think I might as well have them do it too, does any one know hours of labor or replacement cost of the seals??

thanks Charlie

 

[mrboyle]

The valves are sealed in two ways. First and most important is the valve guide. This is an insert that is origionally cast into the head, but can be replaced by cutting out the old one and pressing in a replacement.
Here's an article about valve guides and guide repair: http://members.aol.com/carleyware/library/ar696.htm

The second seal is a rubber or neoprene seal that is placed over the valve stem, under the valve spring. Ths seal works as a wiper (to wipe oil off the valve stem) and as an umbrella (to keep oil from splashing onto the valve stem). These seals are the most common to wear out (they get hard and no longer seal well, or they will just break off altogether). The "blue smoke" everyone has been refering to is usually the result of the "umbrella" seals failing.