oil in the induction system

R

russell

New member
Guys, I need help. I had to overhaul the fuel servo on my 74 8KCAB fuel injected after 300hrs. The shop looked at it and said i had oil in the gaskets and it caused them to degrade. They also told me it was the valve guide leaking oil in the induction system when it is cold. The mechanic I use said the rings were loaded with oil and it was bypassing them (compression too high?).
This engine has 300hrs on it. Does anyone have any light to shed on this problem. Overhaul shop said they see it in acro planes but i do very little of that. I have not seen any oil on start and plugs are changed/cleaned every 50hrs and show no signs of oil?
I use a quart of oil between changes 25hrs, have a filter installed, and use aeroshell 10-40 multi weight.
If it is the rings any suggestions.
HELP
Russell
 
I don't think the rings would cause oil in the induction system. I worked on a 182 with an O470 that had just had a top overhaul. After flying, there was oil dripping out of the carb. What I found was 2 cylinders had the intake vale oil seal installed crooked, allowing oil to be sucked in while taxing back to the hanger, (low manifold pressure). It did not show high oil usage, as when at cruise power the manifold pressure would be closer to ambient pressure. I replaced the 2 seals and all is well now.
I don't think Lyc. uses intake valve seals, but you could do a "wobble test" on the intake valves to see if they have too much clrearance.
Bill Becker
 
Sometimes the oil that is found in the injector servo is not engine oil, it is filter oil from the bracket air filter.
The oil is roughly the same colour, but the filter oil is so sticky that it can plug orfices, and gum up parts inside, as it can even work it's way into the AMC. With the servo off, it should be easy to determine if the oil is running down from the intake sump, or coming from the induction filter.
 
Update:
Found the oil is not coming from the inside, it is from the outside. Got you thinking I bet. The oil was dripping down from something on the back and stoping on the air box. from there it seeped into the inside and on start sucked into the servo. Havent found it on the top side of anything yet and havent found the source on the back but am still in the hunt. Many thanks to all.
 
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