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  #1  
Old 12-16-2019, 02:58 AM
SegevFly SegevFly is offline
 
Join Date: Dec 2019
Location: Melbourne
Posts: 3
Default Oil in the induction system.. Ideas?!

Hi Guys,

Calling on engine people!

We found 3 of 4 cylinders were wet around the inlet valve guide in an IO360 after pouring a not-insignificant amount of oil out of the main engine intake tube (before it branches off to individual cylinders).

Pulled all 4 jugs off and sent them to the a local engine shop.

They all come back with pretty paint, 4 new pistons, few new valves springs, new exhaust valve, new rings and a big $$$ bill. They say we did not replace any of the intake guides as they'd already been done once, can't do again and they looked fine and within the Lycoming tolerance.

We put all the jugs back on. We go flying. 2 hours later, check intake and it's got a puddle of oil in it again.

The engine shop claims it cannot be the inlet valve guides leaking as any oil would be sucked into the cylinder and burnt. There is no way it can be in the intake.

We are now 11 hours after the engine overhaul, been running high power settings for a long period to brake-in the engine per their recommendation, with no sign of improvement.

Interestingly enough, we only lost 0.5qt of oil in these 11 hours..


Attached pictures of the ground below the aircraft, as well as the intake tube

https://ibb.co/ryN7Hyb


https://ibb.co/2tCNmkf

https://ibb.co/dKm3k3N

https://ibb.co/zNZZZss

https://ibb.co/7pY5jZ8

https://ibb.co/2vFYR2q


Open to suggestings and ideas



Many thanks,

Last edited by SegevFly : 12-16-2019 at 03:01 AM.
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  #2  
Old 12-16-2019, 04:32 AM
FredMagare FredMagare is offline
 
Join Date: Mar 2006
Location: Kyle, TX
Posts: 566
Default

Quote:
Originally Posted by SegevFly View Post

The engine shop claims it cannot be the inlet valve guides leaking as any oil would be sucked into the cylinder and burnt. There is no way it can be in the intake.
I'm not sure if this is true.... I'm thinking that there will be oil in the valve covers that can seep past the valve guide after shut down and into the intake. In any case, if it's not causing a problem with power, I'd recommend placing trays under the leaks and keep flying until you're ready to overhaul the engine.
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  #3  
Old 12-16-2019, 01:35 PM
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newt newt is offline
 
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Location: Sydney, Australia
Posts: 370
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Is the main oil seal on the crank leaking, with the oil finding its way into the induction system through the air filter/throttle body?

Your photos don't include anything about the general condition of the engine installation, so I'm just speculating...
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  #4  
Old 12-16-2019, 07:02 PM
kkmarshall kkmarshall is offline
 
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Location: Central Tx
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A friend of mine had oil pooling in the same place and it turned out to be a tiny crack in the sump letting oil in the sump migrate into the intake area. Just FYI
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  #5  
Old 12-16-2019, 08:27 PM
isosceles isosceles is offline
 
Join Date: Jan 2018
Location: Fremont
Posts: 59
Default Sniffle valve?

Have you got a sniffle valve installed on that engine?
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  #6  
Old 12-17-2019, 06:16 PM
pa38112 pa38112 is offline
 
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Location: Clarksboro, NJ
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I do not understand how it is getting on the ground if the oil is in the intake tube. Is it coming out of the throttle body?
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  #7  
Old 12-17-2019, 07:58 PM
Reformed SeaSnake Reformed SeaSnake is offline
 
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Location: Beaverton
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Quote:
Originally Posted by kkmarshall View Post
A friend of mine had oil pooling in the same place and it turned out to be a tiny crack in the sump letting oil in the sump migrate into the intake area. Just FYI
+1

That fits what you?re reporting especially if the engine has a sniffle valve and the oil on the floor is right beneath it. Also, you?d see less oil loss at the high power settings you?ve been running where the pressure in the sump and the intake are similar.
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  #8  
Old 12-18-2019, 02:24 AM
SegevFly SegevFly is offline
 
Join Date: Dec 2019
Location: Melbourne
Posts: 3
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Hi All,

Firstly - thank you for your time looking into my engine issues.

The engine is installed in a Pitts S1S and is a vertical intake. Therefore no sniffer valve, nevertheless, the oil just simply run out of the throttle body, then into the floor via a small drain hole which is located in our air intake.

Based on the comments and suggestions provided, I am going to try and locate another sump, install it on our aircraft and fly to identify if it is the issue, if it does, I will get a new one from Superior or Lycoming

While perhaps costly, I am unable to determine what the oil is coming from otherwise..


I attached some additional pictures for your information, and I promise to let you know how I go!

https://ibb.co/syt2KgJ

https://ibb.co/mHH9Vkz

https://ibb.co/CQ8JjHs

https://ibb.co/nwQ9Xqy

https://ibb.co/hBvxC0c

https://ibb.co/jwgmRH1


Thank you again,
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  #9  
Old 12-19-2019, 08:28 PM
Boyd Birchler Boyd Birchler is offline
 
Join Date: Sep 2014
Location: IN
Posts: 254
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At idle and low power the intake has a vacuum, the rocker box has a good bit of oil in it. Since the intake guides end opposite the end in the rocker box is in a vacuum, some oil will be sucked into the intake port. Most of this oil will go into the cylinder and get burned, the rest drains into the intake system.
On horizontal induction systems there is a one way valve in the bottom of the intake plenum to let this oil and any residual percolated injector fuel drain out. It is called a sniffle valve.
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  #10  
Old 12-19-2019, 11:11 PM
scsmith scsmith is offline
 
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my vote would be a crack in the sump somewhere, or a bad seal somewhere that keeps the sump separate from the intake tubes.
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