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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