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Wed Aug 11, 2010 9:48 pm

Hello friends. I think i know what this is, but i want your opinion(s). I searched the forum for what i think this is and i've been reading about dropped valves. Recently I've been tearing the engine down to clean and track down a huge oil leak. When i parked the bus i was losing huge amounts of oil - I wasn't burning it. No white smoke. Just oil everywhere. After removing most accessories, I found a metal ring loose inside the intake port of the #3 cylinder. You can see in the pictures that there is also some thin metal along the inside of this port. The ring is vertical and seems to be locked around the valve. When i removed the valve covers and took off the rocker assembly the spring looks like it has, well, sprung. After removing the heat exchangers i noticed that the #3 exhaust port was not 'sooty' like the other three ports, but it was 'oily'. When i turned the left side exchanger over a nice quantity of oil came out. If you can tell me for sure what this may be it would really help. Thank you all.

The 'ring' inside the #3 intake port.

Normal carbon deposit inside heat exchanger exhaust from head.

#3 heat exchanger port with oily deposit.

Wed Aug 11, 2010 10:22 pm

Yep...Looks like a dropped seat, terminal case. If that is the valve seat, that head will require massive amounts of welding and machining to rebuild it. You might also have a hole in the piston, which would explain all the oil, and the fact that the cylinder wasn't burning it (no compression). Smell your oil, probably smells like gasoline.

Remove the head, compress the spring and release the valve keepers, and pull out the valve, the damage should be evident.

Actually, once you've got the head off, just a look in the combustion chamber should tell the whole story. But that head has to come off, no matter what. Not the kind of thing that can be fixed without doing so.

Sorry about that, it's the way most aircooled heads go... :cry:

Wed Aug 11, 2010 10:32 pm

DokktorWho222 wrote:

That couldn't possibly be a valve cover shown in your picture, could it? Maybe a remnant from the Titanic?

Thu Aug 12, 2010 12:28 am

They can go that far? But how? wouldn't the valves have stopped closing a long time ago?

Thu Aug 12, 2010 4:00 am

Your inlet valve seat is about the same diameter as your port or even a little larger, so your ring is way too small to be the seat. Even if it was the seat, if the seat had regressed that far the valve spring would have lost tension and the keepers would have come off. Don't know what it actually is though, maybe a valve guide seal that someone installed in the wrong location.

The head needs to be removed no matter what.

Thu Aug 12, 2010 5:42 am

I'm thinking it's the guide seal. Like i said, it's loose in there and it's shallow enough for me to touch it with my finger. I'm going to be tearing off the heads here very shortly. I don't really know the extent of the damage until i get in there. When i started I was hoping it wasn't going to be this bad. Thanks guys.

Thu Aug 12, 2010 7:18 am

Quote: That couldn't possibly be a valve cover shown in your picture, could it? Maybe a remnant from the Titanic?

Thanks Desertbusman, this made my day! :lol: