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Re: REFLECTOR: Brian Questions
> >>Oil temp 210F on climb out 195F cruise.
> Mike: What kind of prop do you have?
> How is your oil cooling set up?
> I have the MT prop.
> Two oil coolers, a washer behind the stiffer spring and really cool CHs.
> Yet I have to stop climbing after 2000 ft because the oil temt gets near
> 230F and the same after several minutes of full power level cruise.
> All that at low to mid 90s ambient.
Simon, I have asked around and have looked at the bypass
assembly (without taking it apart). I also looked at the
old archives from before I took the reflector.
I called and asked Charlie Hart about the theory of operation
behind the oil bypass plate. Charlie worked at the Franklin
factory before it was sold to PZL.
What he said:
The oil pump sends oil to the bypass assembly. The spring loaded
valve in the assembly regulates the oil pressure in the engine.
When oil pressure is low, all of the oil is sent to the engine
and none goes through the cooler (sorry I didn't get specifics,
but he said 55psi). When pressure is greater than 55psi, the
pressure is relieved by sending it to the bottom port -- the
cooler port. The return port simply dumps into the sump.
We should be taking our pressure readings from the
top port -- the same one that goes to the fuel pump. This top
port is branched off of the same galleries that feed the rest
of the engine.
Now, I've looked at the drawings for the bypass assembly, and
it is not clear to me how the arrangement is able to relieve
pressure. I really need to disassemble an oil bypass
assembly, but the only one I have is sitting on the warehouse
floor looking for a buyer. I've talked to Heinly and Hart about
these problems. Heinly has told me that the Poles are
not drilling the fuel pump housings correctly. There are
two oil galleys in the housing. Some of them are being
drilled so that the two galleys intersect. Now this is
my own conjecture, but I think some of the problems
are happening where the high pressure oil that is supposed to
be feeding the engine is instead being released mostly
to the fuel pump housing where there is very little restriction
due to this flaw. Now we have low pressure where we should have
high pressure, and the bypass valve never lets oil to the cooler
because it is not seing the high oil pressure.
Witness the problems and complaints we've been having with
the fuel pumps. There should not be this HIGH pressure
oil against the fuel pump; hence the fix to install an extra
set of bellows in the fuel pump. The engine was certified from
Franklin (not PZL)
with this pump. Why in the last five years has a problem
The oil to the fuel pump housing only lubricates that
cam. Try removing the oil line to the housing and capping
it. See if your oil pressure comes up. You may want to
get the engine warm before doing this.
Brian Michalk <http://www.awpi.com/michalk>
Life is what you make of it ... never wish you had done something.
Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
musician, home-brewer, entrepenuer and SINGLE!