Here are 4 pictures of the exhaust ports of my F20c.

I suspect that the left valve guide of Cyl 2 and both valve guides of cyl 3 are worn and leaking oil into the exhaust port.

However, a bunch of oil was pumped into the intake manifold via the PCV immediately before the engine was last shutdown. It ran for 5 to 10 seconds after a glancing hit off a wall and resulting very rapid 360.

The PCV empties into the intake right in front of the runner for Cylinder 3. The velocity of the air inside would likely carry some of the oil into cylinder 4 but not likely into cylinder 2.

Can anyone confirm this diagnosis?

Exhaust ports for...

Cylinder 1


Cylinder 2


Cylinder 3


Cylinder 4

 

 

Dave, I'm certainly no expert here and I may be in over my head even commenting on this but, would not a compression/leak down test give you some indication of the valve seal/guides condition? Also, what about the possibility of severe ring blow-by in those cylinders?

 

to add information, he's on a brand new (3-4 track days) oem short block with his old existing head.

 

[QUOTE=xviper,Nov 11 2004, 04:02 PM] Dave, I'm certainly no expert here and I may be in over my head even commenting on this but, would not a compression/leak down test give you some indication of the valve seal/guides condition?

 

Thanks for the info Yogi.

I'm going togo on the assumption a large part of what i see is due to oil ingestion via the PCV. I'll install the engine and run it for an hour or two and then remove the header and reexamine the exhaust valves for continued oil contamination. I'll be running a dry sump system at this point and cankcase ventilation wont be routed back into the intake so that should nolonger be a source of contamination.

 

Not sure what you mean by a 'bunch' of oil, but somehow I don't think the amount of oil on the exhaust valve stems could make it thru the intake manifold, intake valves, combustion, and back out the exhaust valves, and end up at the very top of the valve stems. I'm not sure exactly what the airflow looks like through the exhaust ports, but seeing all the oil right where it is looks like a leak. You can even see oil seeping out in the picture of cylinder 2. Anyway, good luck with it.

 

Yup, good points. I was trying to talk myself into not taking the head off. Oh well. Looks like i'll order a new set of seals and guides. I already have new valves and retainers sitting here.

 

Lemme know if you want a hand...or two.

 

Any recommendations on where to buy or rent a valve spring tool would be great. Also, am i correct in assuming that the valve guides are fairly easy to replace using a press?