Black oily soot

by MARK JACKSON in 912 / 914 Technical Questions 8 years ago

I am doing a 5 year hose replacement on a 912ul. When I removed the intake manifolds they are covered in black oily soot from the valves to the carb butterflies on both sides. The plugs are also covered in black oily soot.

Any ideas.

I haven't looked any further yet.

Mark

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Re: Black oily soot

by Rob Seaton » 8 years ago

Rob Seaton

3 1.32k 240

too much oil on the air filter?

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Re: Black oily soot

by Ian Rees » 8 years ago

Ian Rees

6 42 0

Any chance he accidently used the wrong fuel can mixed with 2 stroke oil for a 582 located nearby as a mistake?
Seams like the oil came in the fuel from your description. Check with the owner.

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Re: Black oily soot

by MARK JACKSON » 8 years ago

MARK JACKSON

12 332 11

Hi Rob,

Thanks for the reply. Have you seen this before. It just seems more than a rich mixture to me, but I've not looked closer yet. I was thinking poor valve seals but am clutching at straws. I am going to service the carbs, i'm not sure what i'll find, but if you are certain you are right I will go with that.

Cheers Mark

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Re: Black oily soot

by Roger Lee » 8 years ago

Roger Lee

125 5.12k 4.53k

I've seen it, but usually over oiled K&N air filters. Not sure what else would cause it unless some leak was blown near and air filter and it got sucked in??????????????

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: Black oily soot

by Dennis Richardson » 8 years ago

Dennis Richardson

1 153 169

If this engine has been operating on automotive fuel then I would pull a fuel sample and check for contamination. I have encountered diesel fuel contaminated fuel on several occasions. If the fuel supplier hauled diesel before he hauled gas you can bet on a percentage of contamination. Unlike aviation fuel, automotive fuel doesn't require a dedicated carrier. Add in a driver that's having a bad day......

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Black oily soot

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