X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [64.129.170.194] (HELO VIRCOM1.fcdata.private) by logan.com (CommuniGate Pro SMTP 5.4c2o) with ESMTP id 4891992 for flyrotary@lancaironline.net; Sat, 05 Mar 2011 10:32:53 -0500 Received-SPF: none receiver=logan.com; client-ip=64.129.170.194; envelope-from=cbarber@texasattorney.net Received: from FCD-MAIL06.FCDATA.PRIVATE ([fe80::697f:d6aa:b87:78d8]) by FCD-MAIL05.FCDATA.PRIVATE ([fe80::809d:a06e:5913:452e%15]) with mapi id 14.01.0270.001; Sat, 5 Mar 2011 09:28:24 -0600 From: Chris Barber To: Rotary motors in aircraft Subject: RE: [FlyRotary] Re: Knock sensor and indicator Thread-Topic: [FlyRotary] Re: Knock sensor and indicator Thread-Index: AQHL20Wf1PJYoX2a0U6iAMR64DAVVpQe15d0 Date: Sat, 5 Mar 2011 15:32:14 +0000 Message-ID: <2D41F9BF3B5F9842B164AF93214F3D30357397C1@FCD-MAIL06.FCDATA.PRIVATE> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [166.139.76.11] Content-Type: multipart/alternative; boundary="_000_2D41F9BF3B5F9842B164AF93214F3D30357397C1FCDMAIL06FCDATA_" MIME-Version: 1.0 --_000_2D41F9BF3B5F9842B164AF93214F3D30357397C1FCDMAIL06FCDATA_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Oh, and to share what prompted me to go and tear the engine open again. After replacing the rear springs and seals a couple a weeks ago, I must adm= it that I had a nagging sensation about not replacing the front ones while = I was at it. I dismissed the feeling justifying that when I was checking c= ompression that the front seals seemed to be giving me adequate compression= . I am not sure now where I got my numbers for compression, but the front = were over 80 psi while the rear were at 60 psi (before replacing them). Following replacing the rear seals, I read one of Lynn's post stating that = new seals may get well over 100 psi when new. This was verified with my ne= wly installed rear seals producing around 110 psi. Hmmmmm? 30 psi differen= ce between the rotors? Not to my liking. However, the engine was starting= about as well as ever, even when hot which had been one of my major issues= up to this point. However, the engine had lost a great deal of its smooth= ness. I originally felt I would be able to tune for smoothness (especially= rough at idle and lower power settings), however, the smoothness did not c= ome. I even resorted to using my second EC2 in case I had screwed somethin= g up there. I also checked ALL my wire runs AGAIN...AGAIN. (as I have said,= if I did not have all these fun little tasks to do on the plane, I would l= ikely spend my time practicing law...or arresting people or dating....or...= or....watching "American Idle"....oh, the horror!) As I said, I was able to start pretty easily, however, I could not get it t= o smooth out. So, while giving some thought to the "clues" (yes, contrary t= o what may seem to be the case, I actually do give these matters some thoug= ht), I decided to change the spark plug wires since they were old and insta= lled more to test the system. While doing so it dawn on me that the engine= was hot....(yeah, what insight). Ok, what I mean is that it dawned on me t= hat when I had done my compression test before, I had done so when the engi= ne was cold since the idea of screwing in a compression gage to a hot engin= e was less than appealing. Wait. The compression test should be done whe= n the engine is warm. I never retested once I had warmed up the engine. W= ell, there is not time like the present. So, I redid the compression test.= This time, the compression on the rear rotor was still over 100 psi, howe= ver, the compression on the front housing, while still around 80 ps....was = only giving me TWO "bounces". Yeah, for any noobs on the list, there must = be three "bounces". Also, the chugchuga wosh did not sound "right". DOH! = I checked and rechecked. So, one of the front seals seems bent too. No re= al surprise. Thus, I am now cracking open then engine and replacing all the seals AS I S= HOULD HAVE DONE ORIGINALLY. So much for a false economy. Perhaps that litt= le nagging sensation will not be present this time...I really gotta learn t= o listen to the little sensation......oh, wait, I have you guys too . Chris --_000_2D41F9BF3B5F9842B164AF93214F3D30357397C1FCDMAIL06FCDATA_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Oh, and to share what prompted me to go and tear the engine open again.<= /p>

 

After replacing the rear springs and seals a couple a weeks ago, I must = admit that I had a nagging sensation about not replacing the fr= ont ones while I was at it.  I dismissed the feeling justifying that w= hen I was checking compression that the front seals seemed to be giving me adequate compression.  I am = not sure now where I got my numbers for compression, but the front were ove= r 80 psi while the rear were at 60 psi (before replacing them).

 

Following replacing the rear seals, I read one of Lynn's post stating th= at new seals may get well over 100 psi when new.  This was verified wi= th my newly installed rear seals producing around 110 psi. Hmmmmm= ?  30 psi difference between the rotors?  Not to my liking.  However, the engine was starting abo= ut as well as ever, even when hot which had been one of my major issues up = to this point.  However, the engine had lost a great deal of its smoot= hness.  I originally felt I would be able to tune for smoothness (especially rough at idle and lower power setti= ngs), however, the smoothness did not come.  I even resorted to using = my second EC2 in case I had screwed something up there. = I also checked ALL my wire runs AGAIN...AGAIN. (as I have said, if I did not have all these fun little tasks = to do on the plane, I would likely spend my time practicing law= ...or arresting people or dating....or...or....watching = "American Idle"....oh, the horror!)

 

As I said, I was able to start pretty easily, however, I could not get i= t to smooth out. So, while giving some thought to the "clues" (ye= s, contrary to what may seem to be the case, I actually do give= these matters some thought), I decided to change the spark plug wires since they were old and installed more to test the sy= stem.  While doing so it dawn on me that the engine was hot....(yeah, = what insight). Ok, what I mean is that it dawned on me that when I had done= my compression test before, I had done so when the engine was cold since the idea of screwing in a compression ga= ge to a hot engine was less than appealing.   Wait.  The com= pression test should be done when the engine is warm.  I n= ever retested once I had warmed up the engine.  Well, there is not time like the present.  So, I redid the compression test. = ; This time, the compression on the rear rotor was still over 1= 00 psi, however, the compression on the front housing, while still around 8= 0 ps....was only giving me TWO "bounces".  Yeah, for any noobs on the list, there must be three "bo= unces".  Also, the chugchuga wosh<= a> did not sound "right". DOH!  I checked = and rechecked.  So, one of the front seals seems bent too.  No re= al surprise. 

 

Thus, I am now cracking open then engine and replacing all the seals AS = I SHOULD HAVE DONE ORIGINALLY. So much for a false economy.  Perhaps t= hat little nagging sensation will not be present this time...I really = gotta learn to listen to the little sensation......oh, wait, I have you guys too <g>.

 

Chris

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