|
Chris,
Not certain where you have your oil pressure sensor, but
on my old 13B it is after the filter and oil cooler - actually its on the
aluminum block. The point is my pressure sensor is after all of
the components in the cooling system. I suspect your's is as
well.
So assuming your oil pump is OK here is what we have
remaining.
1. There is an "O" ring between the aluminum
front cover and the iron housing (unless it has been removed and some
substitute is there). If this gets pushed out the oil pressure tyically
drop down to around 20-30 psi at max rpm). It will generally permit
some oil to flow.
2. If the filter becomes clogged then most oil
filters have a high pressure by-pass which permits oil to flow even thought it
will not be filtered (better some dirty oil rather than a fried main
bearing)
3. Hoses that have "Earls" type aluminum fittings
have been know to shave a rubber flap when being installed and could have gotten
into a position to block flow.
You keep remarking that the oil flows to the filter but
not past it - even when you filled the filter with oil. That would cause
me to try replacing that filter with a different one. Oil filters have
been know to have their internals collapse and block flow. Unlikely - but
you are looking for any possibility to preclude tearing into the engine so don't
over look this one.
As several have suggested you really need to have a
mechanical pressure gauge to see what your oil pressure is. You may have
to cook up some An fittings to block the oil flow before it gets to the filter
and insert a pressure fitting and gauge at that point. As long as your
engine does not start have no oil flowing for few revolutions should not hurt
your bearings - take a reading - if pressure doesn't come up with the flow
blocked by your measuring device then you have an internal problem. Could
be the "O" ring, could be the keys in the pump (I had that happen to me once -
flew for 10 hours before the clamping nut on the oil shaft let go and pressure
dropped during taxi - fortunately), could be the pump, could be your oil pick
up.
Good luck
Ed
Sent: Wednesday, September 29, 2010 1:43 PM
Subject: [FlyRotary] Re: Oil Pressure Loss
Sorry, I have had some major issues with notebook computer I usually use at
home. Most recently with the mouse freezing, so, I had to use three post
that should have been one.
I have NOT had the engine apart. It has about 45 hours on it since I
performed the latest rebuild using mostly new parts (rotor & end housings,
rebuild kit...old rotors and e-shaft). It had been running damn good, good
enough that I thought I was really close to the DAR sign off and first flight
attempt. The RPM indicator drop was a residual issue with
the EM2 I was working on trying to tie up loose
ends.
As I mentioned, I would have not had noticed an issue just listening and
watching the engine, but while I was trying (unsuccessfully) to solve my RPM
drop reading problem I noted the OP flashing and the
low pressure reading.
I am getting some oil coming out of the front of the engine and into the
remote oil filter which is located between the engine outlet and the coolers,
however, I have apparently not had enough pressure to move oil out
of the filter. I replaced the filter and the same thing
occurred . Perhaps I have not cranked the engine long enough to move
it through the filter as it was getting dark and I had not yet moved the spark
plugs and was concerned about damaging the internals and
PSRU .
Even though I am getting flow out of the engine when cranking with the
plugs installed, I do not know how much flow it is....it is steady, but does not
seem all that strong, but of course, the engine is only cranking and not
running. Also, since I had no oil flow, I was concerned about cranking it
without oil getting to the engine and PSRU . I hope to get
out to the hangar later today and continue my checks with the plugs
removed. I am not too hopeful though, it seems as if it must
be an internal issue, especially since the mechanical gauges I
hooked up also showed low/no pressure.
I agree, I do not wish to tear down the engine, as I have a lot installed
on top of it, plus the PITA of opening the dang thing up. However, I have
gotten pretty good and uninstalling and reinstalling...(of
course, apparently not good enough to not have a problem). The
process has gotten much faster as I have become more methodical.
Dave mentioned some of the issues we know about with keys and retaining
clips. While something like that could certainly be the problem, I am
certain I addressed these very items, even though possibly not well
enough. If you would have asked, I would have thought it was good, but now
the evidence will tell.
I have removed most the hoses to check for obstructions and have yet to
find any. Again, the oil is coming out of the front of the engine in a
stream but low pressure with simple starter cranking, but as of yet has not made
it past the filter, which is the first "event" in the chain.
Do we know of a way to determine how much oil should be flowing with simple
cranking...such as "x" amount into a jar in "y" time cranking? Yeah,
grasping at straws...but I am trying to get use to the idea of pulling the
engine.
Heavy sigh.
Thanks,
Chris
From: Rotary motors in aircraft [flyrotary@lancaironline.net]
on behalf of Bill Brwhadburry [bbradburry@bellsouth.net]
Sent:
Wednesday, September 29, 2010 12:00 PM
To: Rotary motors in
aircraft
Subject: [FlyRotary] Re: Oil Pressure
Loss
Chris,
Did you just have your
engine apart? If so, did you have oil pressure after that? Oil
from the pump comes out of the lower front housing and goes to the cooler.
Did you check to see if oil is coming from the first opening after the
pump? If it is not, the problem is inside the engine, if oil is coming
from the pump, the problem is outside the engine. Cooler, filter, hose,
etc, don’t tear it down unless you have to. If you didn’t use a
mandrel when you made up your hoses, you could have a sliver of the inside of
the hose blocking the oil flow.
Bill B
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Chris Barber
Sent: Tuesday, September 28, 2010 11:26
PM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Oil Pressure Loss
Oh, and maybe this is
too obvious, but when I drop the pan, what should I be looking for. Yeah,
large metal shards I would figure out, but if it is not that obvious, where do I
need to focus. The pressure gage?? The pump?? Something
else??
From: Rotary motors in
aircraft [flyrotary@lancaironline.net] on behalf of Chris Barber
[cbarber@texasattorney.net]
Sent: Tuesday, September 28, 2010 10:11
PM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Oil Pressure Loss
Geeesh...the mouse
froze again.
To continue, I got a
moderate, steady stream of oil coming from the remote filter mount. So, I
had some flow. I then went to the end of the hoses where it re-enters the
engine after flowing through the two oil coolers. Well, here there was no
joy. No oil coming out. I did refill the filter before I reinstalled
it and cranked the engine for quite a while to no avail. Next, I unhooked
a few of the other hose connections past the filter and still no flow when
cranking. Finally, I checked all the way back to the filter outlet and no
oil would come out. I changed to a different filter and still no flow from
out of the filter. So, I have some flow....not a lot into the filter buy
none out.
I HATE the idea of
dropping the pan (will be a real pain) to check the oil pump and pressure gage,
but I am not quite sure as what else to check at this point. When I return
tomorrow, I will remove the plugs to take some of the stress off the starter and
see if I get flow out of the filter. I am also concerned now that I
have been cranking the system long enough that some important parts are
not running with a lot of needed oil, such as the PSRU
etc.
If I would have just
happened to look at the OP gauge, I would have never known there was a problem
as the engine "sounded" strong and smooth and continued to do so when I started
it to test my pressure after discovering the problems.
Hopefully this will
be a bit more directly answered by the engine guru types on the list since
it is not specific to Tracy's electronics.
Please, what else
should I check, I am about at the end of my testing skill set. Also, what
say ye as to what the problem "sounds" like????
From: Rotary motors in
aircraft [flyrotary@lancaironline.net] on behalf of Chris Barber
[cbarber@texasattorney.net]
Sent: Tuesday, September 28, 2010 9:59
PM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Oil Pressure Loss
Aggg. I need a new
computer. The mouse froze and the message sent
prematurly.
Anyway, I rechecked
the wires to the EM2 and at the sensor again and all checked fine.
Again, I started the engine, but was shut down as soon as I still saw no
pressure.
Next, I hooked up two
separate mechanical pressure gages in three different locations in the oil
system, started the engine three times very briefly. Each time
the engin started and seemed to run fine for the VERY short time I allowed
it to run. No pressure reading on two of the test points, and
about 6psi on the reading from the turbor engine outlet to the
turbo.
Ok, I unscrewed the
oil filter, which is located remotely just as the oil comes out of the front (by
the pully's oposite the prop) of the engine. I hooked up a
remote start switch, climbed under the engine and cranked the engie.....I got a
moderate, steady flow of oil
From: Rotary motors in
aircraft [flyrotary@lancaironline.net] on behalf of Chris Barber
[cbarber@texasattorney.net]
Sent: Tuesday, September 28, 2010 9:42
PM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Oil Pressure Loss
In the never ending
tradition of two step forward and three steps back, I was working on my RPM drop
out at 6000 rmp (messed with seveal resistors to no avail). As I
was sitting on the ramp at idle for a few minutes, focusing on
the RPM's I glanced over at the Oil Pressure and noted it was flashing as
an alert and was showing almost NO oil pressure (4 or 5 psi). I instantly
shut down the engine.
The engine appeared
to be running fine before I shut it down. I checked the wire to the back
of the engine monitor and all was fine. I also checked the continutiy
of the wire to the sensor and it was good. I started the engine again and
it started fine and seem to run fine, however, the OP did not kick in so I shut
it down
again
|