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  #1  
Old 07-21-2018, 09:01 PM
rvator4twa rvator4twa is offline
 
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Default High silicone in oil analysis

I have changed the oil twice in my rebuilt O360 with mineral oil in each, once at 35 hours and again at 70. Both times silicone was high. That last time it was 34.5. I burn mostly 93 Octane ethanol auto fuel with some 100 LL as I have an 8.5/1 compression ratio. Any ideas if this is normal?
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  #2  
Old 07-21-2018, 09:45 PM
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Jesse Jesse is offline
 
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Silicon is usually a result of poor air filtration, letting dirt get into the engine. Check the status of your air filter and make sure it is well sealed in the air box.
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  #3  
Old 07-21-2018, 09:59 PM
rvator4twa rvator4twa is offline
 
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Default Silicon

Other than looking at it which I have, is there a technique to use to do this?
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  #4  
Old 07-22-2018, 03:00 AM
Marc Bourget Marc Bourget is offline
 
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With car engines, one technique is using starting fluid, small careful doses, but the fan on a car is much smaller and protected.

Just looking maybe should be expanded into some careful disassembly and searching for the slightest trace of incursion.
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  #5  
Old 07-22-2018, 05:59 AM
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snopercod snopercod is offline
 
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I started another thread on this when I had the same problem: http://www.vansairforce.com/communit...t=high+silicon

For me, the solution was to re-direct to outlet of the oil separator to a catch bottle rather than back to the crankcase. YMMV.
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  #6  
Old 07-22-2018, 06:21 AM
phapp phapp is offline
 
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My Blackstone analysis usually gives me some reasons / ideas to look into. They also answer questions via email.

I too had silicone in my A-65 in my Champ. In addition to the air filter, any silicone sealants used in the rebuild can also find there way into the oil (not the problem in my case). Another option my A & P mentioned were the Real rocker cover gaskets that might have worn in since installation. I don't know about that one.

Dirt introduced during annual and the air filter cleaning / reassembly could be another source.

Yet another, but unlikely source is leaving the plug holes open for the 2 weeks of its last annual.

At any rate, my levels dropped without doing anything different.

When it comes to engines, cleanliness is extremely important.
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  #7  
Old 07-22-2018, 10:34 AM
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erich weaver erich weaver is offline
 
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Silicon and silicone are two very different things with different origins. Google and make sure you know which one was actually elevated.

Erich
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  #8  
Old 07-22-2018, 11:07 AM
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vlittle vlittle is offline
 
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A common source of elemental silicon in your oil analysis is from silicone grease (DC-4) used as a lubricant on the oil filter rubber sealing ring.

If you don't do your own filter changes, your mechanic may be too liberal with the grease. It should be applied sparingly.
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  #9  
Old 07-22-2018, 11:38 AM
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snopercod snopercod is offline
 
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Quote:
Originally Posted by vlittle View Post
(DC-4) used as a lubricant on the oil filter rubber sealing ring.
I used to use DC-4 but now I buy the Tempest Spin-EZ filters that you don't need to lube.
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  #10  
Old 07-22-2018, 08:18 PM
vic syracuse vic syracuse is offline
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Silicon is dirt, which is different than the silicone you use on the oil filter..

Vic
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