REFLECTOR: No oil pressure

Chuck c.harbert at comcast.net
Thu Sep 6 12:59:10 CDT 2007


Scott, when we were building race engines, we would never start them until 
the entire system was primed (lines, oil filter, pump, oil coolers, etc) and 
produced oil pressure. These were very expensive motors like your turbo 520. 
You can use a cheap pulse type fuel pump tapped into the oil system to fill 
everything. Next we cranked the engine with the spark plugs removed to 
ensure oil pressure, and finally fired the engine.

It takes very little running without oil pressure to score the rod bearings 
which can result in broken rod or crank, especially in a turbocharged 
engine. After you run it for testing, I'd send in an oil sample before I 
flew it to be sure your don't have excessive bearing metal. I'd also replace 
and cut open the old oil filter to look for metal.

I don't mean this to sound like the end of the world, but this could be very 
serious. Hope you find nothing.

Chuck H


>> From: "Scott Derrick" <scott at tnstaafl.net>
>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>> Sent: Wednesday, September 05, 2007 9:10 AM
>> Subject: Re: REFLECTOR: Chevy numbers
>>
>>
>>> Had a bummer happen yesterday.
>>>
>>> First start of my TSIO520 went well after a few false attempts.  She
>>> sounded good but the oil pressure never came up after about 30 seconds.
>>> Put a mechanical gauge on a pressure outlet, Re primed the engine with
>>> oil and tried again. No joy.
>>>
>>> I could see the mechanical tach output turning when I rotated the prop.
>>> Its driven by the main oil pump impeller.  So the oil pump is turning.
>>>
>>> removed the oil filter, it was dry!!!
>>>
>>> pulling the pan today to check the sump.  If that reveals nothing will
>>> inspect the pressure relief valve.  After that I'll have to pull the
>>> engine off the firewall to remove the oil pump....
>>>
>>> Scott



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