REFLECTOR: Engine/Prop woes

[Scott Derrick]

Chuck,

Good idea.  I guess I was assuming the electronic  dynon sensor/gauge
would be the most accurate.

Scott

Chuck Jensen wrote:
> Hi, Scott,
>
> Step number 1.  Find out what your oil pressure is.
>
> That may sound stupid, but you only think you know what it is, based on the Dynon readout.  I had the same low oil problem in  my IO-540 Lycosaurous, so a mechanical direct read gauge was plumbed in to take physical readings, rather than sensor readings.  Turns out through the different temp ranges, the actual readings were 7-10 psig higher than what was displayed on the GRT EFIS, which put me within normal ranges.  Likewise I was concerned about the very low oil pressure at idle with hot oil, but it turns out that's within normal ranges as well.
>
> As they say, or at least I do, 'before you solve a problem, make sure you have one'.
>
> Chuck Jensen
>
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Scott Derrick
> Sent: Sunday, July 19, 2009 8:41 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: REFLECTOR: Engine/Prop woes
>
>
> I received my prop back from Catto a week and a half ago.  This was the
> 2nd go around in an attempt to re-pitch it for the reduced horse power
> of my 520, since I decided leave the turbo on the bench.
>
> I waited to remount it as I was deep into building new engine cowls and
> didn't want to switch gears. 
>
> Finally finished the cowlings enough that I can work on them with the
> prop on the engine so remounted the prop yesterday and fired her up.  I
> had left the tuning project dangling a month ago because my static was
> so low I was afraid it may be effecting the setup procedure. 
> Continental and Cessna only provide a setup procedure that assumes your
> running a constant speed prop...
>
> Well the bad news is the static is still too low in my opinion.  I did
> see 2060, which is better than the 1930 I was seeing before, but 2060 is
> pretty low.  It was very hot, close to 100 and density altitude was
> approaching 11,000 ft. That does seem to reduce static RPMs somewhat.  
> I emailed Catto to see what he thinks. He didn't charge me for the 2nd
> repitch but it still costs me $$250 for every round trip of the prop.
>
> I was thinking maybe the RPM would pick up with just a bit of forward
> speed?  Maybe at 50 knots?  I might take her out on the runway and see
> how she does on a fast taxi test..  Probably just wishful thinking.
>
> The real bummer though was not the prop. I was running the engine a lot.
> probably 10 starts and stops with a full throttle engine run every
> time.  I have never really gotten the engine hot and that was one of my
> goals for this test run. Finally got the oil temp up to 210 degrees
> which allowed me to see that all the joints in the oil lines from the
> engine up to the nose and back though the two heat exchangers were all
> tight with hot oil.  The bummer was I noticed the oil pressure at 210
> degrees F was down to 35 at 2000 rpm and dropped to 11 at idle.   I got
> a  low pressure  alert from the Dynon!  WTF?  The oil pressures are well
> within spec at the 140 degree mark, which is all the engine book lists..
> I've changed the oil filter twice on this engine and cut both open.  The
> first had a minuscule amount of metal, not nearly as much as I would
> expect from a fresh rebuild. The second change had almost none so I
> don't think its an internal wear problem.  Well I was bummed and pushed
> her back in the hanger to think things through(and cry in my soup!). 
> Talked to the AP/IA on the field who supervised the rebuild.  NO clues..
>
> Got home and started search the Internet.  Found a reference on
> SacSkyRanch one of my favorite mechanics sites.  They had a  list of
> about 25 items that could cause low oil pressure.  Most were of the low
> all the time, which I don't have.  They had the classic dirty seat on
> the pressure regulator which I already knew about and was planning on
> checking. Then near the bottom they listed a bunch of Continental turbo
> charged engines.  Said if you are running "Full Flow Lifters" on the
> exhaust valves to improve cooling of the valves  they can reduce
> pressure  5-7  psi.   Well I'm running  "Full Flow  Lifters" on all  12
> valves, per  ECI's  recommendation!  A possible 10-14 PSI reduction! 
> Which if added to what I was seeing puts me way into the high end of the
> green.   I hope this is it. I'm calling Continental next week to verify
> this...
>
> At least the cowls are ready for their first  shot of primer and the 
> induction scoop/filter  box/ alternate  air box combo is close to done
> also.
>
> Scott
>
>
>
>
>
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