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[70.193.206.192]) by mx.google.com with ESMTPS id t8sm55276509anj.2.2013.02.17.07.41.05 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 17 Feb 2013 07:41:07 -0800 (PST) Subject: Re: [FlyRotary] Re: That damn O-ring again! References: From: Tracy Content-Type: multipart/alternative; boundary=Apple-Mail-5A6AF958-9106-4502-B062-34D74B3883BE X-Mailer: iPad Mail (10B141) In-Reply-To: Message-Id: Date: Sun, 17 Feb 2013 10:41:04 -0500 To: Rotary motors in aircraft Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-5A6AF958-9106-4502-B062-34D74B3883BE Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable The Renesis uses a thin metallic front cover gasket so it should not have th= e O-ring issue. T Sent from my iPad On Feb 17, 2013, at 9:49 AM, Charlie England wrote: > Is this also an issue with the Renesis engine?=20 >=20 > Charlie > (My email account has been so quiet since the 14th, I was wondering if the= re'd been another Valentine's Day Massacre.) :-)=20 >=20 > On 02/17/2013 08:02 AM, Tracy wrote: >> Todd, I'm wondering what the 'recommended' fix was that you tried first. = Like Mark, I'm also wondering where the counterbore for the O-ring went. >>=20 >> The problem as I understood it (on series 4 engines which most are using)= was originally caused when the engine was re-assembled using Mazda's replac= ement gasket set that has a front cover gasket MUCH thicker than the origina= l. This spaces the front cover about .015" farther away from the counterbo= re and allows the o-ring to expand out into the gap where it it sheared by t= he edge of the counterbore when the oil pressure spiked on a cold start. >>=20 >> The fix that Racing Beat recommended to me was used and documented in the= conversion guide. It was to NOT use the gasket at all and use Ultra Gray R= TV gasket maker instead. This worked for 856 hours on my original engine a= nd never failed. =20 >>=20 >> As always, YMMV. >>=20 >> Tracy >>=20 >> Sent from my iPad >>=20 >> On Feb 17, 2013, at 7:35 AM, Lehanover@aol.com wrote: >>=20 >>> The problem is that the front cover is very flexible and there is no fas= tener near this junction. (Thank you Mazda) >>> On a cold start the oil pressure at this junction can far exceed the pop= pressure of the stock pressure relief valve located at the base of the rear= iron. On some models of front iron there is a relief valve just below this j= unction set at 140 pounds. This is to protect the oil cooler, which is a goo= d idea but is too high a pressure to keep the junction from pushing open and= releasing the "O" ring. =20 >>> =20 >>> The object of the thick glass reinforced white washer (probably Teflon o= r Nylon) fitted at this junction was to create added pressure between the al= uminum and the cast iron. It's a spacer. >>> =20 >>> If Mazda had left the aluminum tube .060" taller than the gasket surface= Or installed a fastener close by, they would never have had this problem >>> =20 >>> This was a Mazda fix for the problem that had some success. The washer t= ook up some space and then a thicker "O" ring was installed to do the sealin= g. The washer might have done some sealing if oil had slipped past the "O" r= ing, but it could have been made of any sturdy material. Steel or aluminum. >>> =20 >>> Later versions of the front cover gasket had extensions of hard paper th= at fit around the washer. (And did nothing). Later still a composition gaske= t with a stainless face replacing the washer. There was never an attempt to f= ix the cause. Just cheap gags to prevent the outcome. >>> =20 >>> Your fix looks just fine. I would make the ID of the brass tube just a b= it bigger and taper the ends for less drag. Oil goes through here at a fairl= y high rate. >>> =20 >>> I have not seen how this was done on FD or Renesis engines. >>> =20 >>> Lynn E. Hanover >>> =20 >>> In a message dated 2/17/2013 5:57:16 A.M. Eastern Standard Time, msteitl= e@gmail.com writes: >>> Todd,=20 >>>=20 >>> What happened to the counter-bore in the front iron? Did your model not= have a counter-bore? It appears to have been filled in with Devcon (or JB)= ? The walls of the counter-bore are supposed to hold th= e o-ring in place and prevent it from being forced out under pressure. At l= east that's my understanding of how it works. =20 >>>=20 >>> =46rom the pictures, it appears that the thick-wall bushing will be chok= ing off much of your oil flow, possibly causing other problems (bearing fail= ure). >>>=20 >>> Mark S. >>>=20 >>> On Sun, Feb 17, 2013 at 1:34 AM, Todd Bartrim wrote:= >>>> Hello All; >>>> It's been awhile since I last posted, though I've been reading almost e= very post to sort of keep up with the latest developments. >>>> The last time I flew I was seeing lower oil pressures around 35-40 p= si, so I decided to pull the front cover the other day. I had previously had= a complete O-ring failure so had done the recommended fix at the time. When= I pulled it the other day, everything looked good but obviously wasn't. I r= ecalled Chris having a repeat of this last fall so searched the archives and= found a reference to him pushing a small cylinder in there. There was also a= previous post where Lynn commented on somebody else's idea of a Teflon wash= er being a good idea. So I've decided to do both. Attached pics should show i= n better detail than I could explain. I've done a trial fit, but will await c= omments before I assemble with sealant. >>>>=20 >>>> Todd Bartrim >>>>=20 >>>> C-FSTB >>>>=20 >>>> -- >>>> Homepage: http://www.flyrotary.com/ >>>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/L= ist.html >=20 --Apple-Mail-5A6AF958-9106-4502-B062-34D74B3883BE Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 7bit
The Renesis uses a thin metallic front cover gasket so it should not have the O-ring issue.

T

Sent from my iPad

On Feb 17, 2013, at 9:49 AM, Charlie England <ceengland7@gmail.com> wrote:

Is this also an issue with the Renesis engine?

Charlie
(My email account has been so quiet since the 14th, I was wondering if there'd been another Valentine's Day Massacre.) :-)

On 02/17/2013 08:02 AM, Tracy wrote:
Todd, I'm wondering what the 'recommended' fix was that you tried first.  Like Mark, I'm also wondering where the counterbore for the O-ring went.

The problem as I understood it (on series 4 engines which most are using) was originally caused when the engine was re-assembled using Mazda's replacement gasket set that has a front cover gasket MUCH thicker than the original.   This spaces the front cover about .015" farther away from the counterbore and allows the o-ring to expand out into the gap where it it sheared by the edge of the counterbore when the oil pressure spiked on a cold start.

The fix that Racing Beat recommended to me was used and documented in the conversion guide.  It was to NOT use the gasket at all and use Ultra Gray RTV gasket maker instead.   This worked for 856 hours on my original engine and never failed.   

As always, YMMV.

Tracy

Sent from my iPad

On Feb 17, 2013, at 7:35 AM, Lehanover@aol.com wrote:

The problem is that the front cover is very flexible and there is no fastener near this junction. (Thank you Mazda)
On a cold start the oil pressure at this junction can far exceed the pop pressure of the stock pressure relief valve located at the base of the rear iron. On some models of front iron there is a relief valve just below this junction set at 140 pounds. This is to protect the oil cooler, which is a good idea but is too high a pressure to keep the junction from pushing open and releasing the "O" ring.  
 
The object of the thick glass reinforced white washer (probably Teflon or Nylon) fitted at this junction was to create added pressure between the aluminum and the cast iron. It's a spacer.
 
If Mazda had left the aluminum tube .060" taller than the gasket surface  Or installed a fastener close by, they would never have had this problem
 
This was a Mazda fix for the problem that had some success. The washer took up some space and then a thicker "O" ring was installed to do the sealing. The washer might have done some sealing if oil had slipped past the "O" ring, but it could have been made of any sturdy material. Steel or aluminum.
 
Later versions of the front cover gasket had extensions of hard paper that fit around the washer. (And did nothing). Later still a composition gasket with a stainless face replacing the washer. There was never an attempt to fix the cause. Just cheap gags to prevent the outcome.
 
Your fix looks just fine. I would make the ID of the brass tube just a bit bigger and taper the ends for less drag. Oil goes through here at a fairly high rate.
 
I have not seen how this was done on FD or Renesis engines.
 
Lynn E. Hanover
 
In a message dated 2/17/2013 5:57:16 A.M. Eastern Standard Time, msteitle@gmail.com writes:
Todd, 

What happened to the counter-bore in the front iron?  Did your model not have a counter-bore?  It appears to have been filled in with Devcon (or JB)?  The walls of the counter-bore are supposed to hold the o-ring in place and prevent it from being forced out under pressure.  At least that's my understanding of how it works.  

From the pictures, it appears that the thick-wall bushing will be choking off much of your oil flow, possibly causing other problems (bearing failure).

Mark S.

On Sun, Feb 17, 2013 at 1:34 AM, Todd Bartrim <bartrim@gmail.com> wrote:
Hello All;
It's been awhile since I last posted, though I've been reading almost every post to sort of keep up with the latest developments.
    The last time I flew I was seeing lower oil pressures around 35-40 psi, so I decided to pull the front cover the other day. I had previously had a complete O-ring failure so had done the recommended fix at the time. When I pulled it the other day, everything looked good but obviously wasn't. I recalled Chris having a repeat of this last fall so searched the archives and found a reference to him pushing a small cylinder in there. There was also a previous post where Lynn commented on somebody else's idea of a Teflon washer being a good idea. So I've decided to do both. Attached pics should show in better detail than I could explain. I've done a trial fit, but will await comments before I assemble with sealant.

Todd Bartrim

C-FSTB

--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html



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