REFLECTOR: No oil pressure

Scott Derrick scott at tnstaafl.net
Mon Sep 10 20:43:39 CDT 2007


Alex,

I did the rebuild and used a lithium based assembly grease and 20-50 
motor oil during assembly.

I did show 3 psi turning it through with the mags shorted to ground. 
Thought that was OK since it wasn't turning very fast, I think that was 
the small amount of oil and grease in the pump when I assembled it. once 
it pumped out it dropped to 2 psi.  I never saw zero, but considered 2 
psi as close enough.

We also pre oiled(1/2 quart) the main oil galleys which oils the 
bearings before each start event.  The third try, which immediately 
produced 85 PSI at 800 RPM, I filled the oil pump, and pre-oiled 2 
quarts into the galleys which also filled up the filter.

The TSIO520 has a unique oil pump that uses a single impeller for both 
the pressure pump and the scavenge pump for the turbo. What I didn't 
know and wasn't in the overhaul manual is that you need "a lot" of oil 
in the pump for it to self prime if the turbo line is dry.

I really think the bearings are fine though I will probably send in the 
second & third oil change for metal analysis, and I always cut open and 
inspect the old filters.  I do a first oil change at about 2-3 hours.. 
All new engines make a little metal during the first couple hours, fact 
of life...

Scott

Alex Balic wrote:
> Always crank a new engine with the plugs removed until you see oil pressure-
> this is a golden rule in my book- I have always used STP oil treatment for
> assembly lube anyway- it is sticky and stays put until the oil gets to the
> parts which can take some time on a clean engine. I would think that whoever
> rebuilt Scott's engine did this, he might need to call them to verify, can
> he put a mechanical gauge on it to check somewhere else?
> 
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Chuck
> Sent: Thursday, September 06, 2007 12:59 PM
> To: reflector at tvbf.org
> Subject: REFLECTOR: No oil pressure
> 
> 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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deserve neither security nor liberty.

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