Mailing List flyrotary@lancaironline.net Message #58896
From: <Lehanover@aol.com>
Subject: Re: [FlyRotary] Re: Oil pressure again
Date: Sun, 26 Aug 2012 19:43:05 -0400 (EDT)
To: <flyrotary@lancaironline.net>
The "O" ring junction has killed thousands of rotaries. The Mazda people will not admit that the design is at fault, as senior engineers would "loose Face" Not done you see. But the fact remains it is a stupid design. The front cover is held on the very minimum number of bolts. The cover is very flexable, and  an oil pressure spike pushes the junction apart a bit, and a piece of the "O" ring is pushed outside the junction. So, then the piece of "O" ring holds the junction open, and forms a massive oil leak and you get 20 PSI tops. (depending on the oil weight and the temperature). A bolt should have been installed right beside the junction to clamp the cover tight to the iron.
 
In the early years we just left off the gasket to get the tube to zero clearance over the "O" ring. Worked most of the time.
Oil leaks from the case mating surface were common.
 
These failures were with the early relief valves set at 71.9 PSI. On a cold start with a blip of the throttle, the valve could not open fast enough and the "O" ring would blow out. Then they tried the Nylon washer to fit outside the "O" ring, and increase the preload on the tube. The "O" ring used is then thicker than the early "O" ring to account for the taller space to fill. In every case the higher you set the oil pressure, the more likely you are to see this failure. I do not use this gallery, or the stock oil pump, so I quit screwing with this failure years ago.
I use 100 PSI of oil pressure.
 
Then they went to a stainless flanged sheet metal washer formed into a stainless faced gasket. I have seen this gasket but I do not know if an "O" ring is still involved. I would drop the "O" ring idea, and go to a solid copper washer to fit the shape of the hole in the iron. The washer needs to be about .040" proud of the surface so as to create a good amount of preload from the tube, to hold the washer in place. So, you get preload, and a gasket (the copper washer) that will not fail or blow out of place during an overpressure. You might loose a pound or two of peak oil pressure but the junction would never fail again, and you can use the front cover gasket.
 
Or I could be completely wrong.
 
When installing a new pump, pack it with grease or vasoline to be sure to get a good prime on start up. lube the hole in the cast iron as well.
 
Lynn E. Hanover
 
In a message dated 8/26/2012 2:29:03 P.M. Eastern Daylight Time, cbarber@texasattorney.net writes:
I don't think it is the sensors as I have two and the drop is consistent on both. I have both the RWS sensor and the Dynon.   It seems to be having trouble getting in the mid 20 psi range.

I have a busy week so I think I am about to order new oil pump and O-ring and spacer  Hopefully it will arrive about the time my time frees up  I figure it can't hurt and that will pretty much make everything in the engine new except the rotors and e-shaft.

Chris

Sent from my iPhone 4

On Aug 26, 2012, at 1:15 PM, "Bobby J. Hughes" <bhughes@qnsi.net> wrote:

> Chris
>
> How much has it dropped? Could it be the sensor? I had one fail early in phase 1. Every time I pitched up the pressure would drop and trigger an alarm.
>
> Bobby
>
>
> Sent from my iPad
>
> On Aug 26, 2012, at 9:11 AM, "Chris Barber" <cbarber@texasattorney.net> wrote:
>
>> My oil pressure has dropped again. I am jumping to the conclusion it is that pesky front cover O-ring. I know I was meticulous with installing it last time. While it may be something else, I doubt it. I had the pressure valve fall into the pan a couple of years ago and it is now safety wired in. Perhaps it is the oil pump but it seems so simple and not prone to failure.
>>
>> So, to make this more than a vent, as I know mostly how to address this....contrary to the evidence that I am having to screw with it again, is there any words of wisdom y'all would care to share. Since I will at least have the front cover off (should be able to do do with engine on the plane) would this be a good time to replace the oil pump. It has not been replaced in the past do it is many years old with an unknown number of miles. Is there a "better" oil pump out there than the turbo version offered by Mazdatrix that I should ponder?
>>
>> I may have the oil ring and plastic retaining ring already if I can find them. Just gotta find the time to crack into it.  Then to continue my turbo diagnosis. Great power without intercooler (even though I found no restriction, but it is a super cheap intercooler from eBay) and blow off valve or even N/A. Obvious limited breathing with the cheap intercooler and blow off valve
>>
>> TIA.
>>
>> Chris Barber
>> Houston
>>
>> Sent from my iPhone 4
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