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Air start issue

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Mozam

Joined: 24 Nov 2006
Posts: 85

Posted: Mon Sep 24, 2007 4:47 am Post subject: Air start issue

My -52TW has both air and electric start.  Recently the air start is acting up.  When the engine is hot (higher compression than when cold) it can barely, if at all, get the engine to rotate.



It often hangs up and I can hear the air just hissing out while the prop struggles to move.  Sometimes I can "bump" it to get the prop past the sticking point.



It was working fine and all other air systems are still working fine.

It "appears" as though the air distributer timing has slipped.  Is this possible?



Thank goodness for the electric start, which can spin the engine up to idle speed.



Thanks,

Steve Dalton

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ReadeG(at)Cairnwood.com
Guest

Posted: Mon Sep 24, 2007 5:06 am Post subject: Air start issue

Steve:



Had similar situation with the Wilga.  First we replaced several of the

air injectors that were sticking.  Second we had to replace the "spider"

or air distributer - lots of moisture damage (btw - Mort will probably

never do that again).  Third we removed the step down valve which has

improved starting 100%.  This item is not an issue with the Yaks.  The

alignment of the brass plate in the air distributer is critical - I

would check with Mort on that one.  Otherwise I would look for a stuck

air injector. 



Reade Genzlinger

Cairnwood Cooperative Corporation

mailto:readeg(at)cairnwood.com

215.914.0370



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viperdoc(at)mindspring.co
Guest

Posted: Mon Sep 24, 2007 6:09 am Post subject: Air start issue

Steve,

Is that hissing at your left foot? Most likely you have a problem with the

seals in your air start valve. Could be the solenoid. I went through this

about a month ago. It is in one hell of a place to get to. It is on the left

side of the interior firewall. The good news is that the new CJ air start

valves are a duplicate of the RU ones. It is a straight swap. The pain in

the ass that it is because of the placement. The Chinese put theirs on the

firewall with the engine not behind it! Doug Sapp has them is stock now. I

have two shot ones on the shelf now. One recently rebuilt and the other the

original that started the problem.

Doc



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drc(at)wscare.com
Guest

Posted: Mon Sep 24, 2007 8:59 am Post subject: Air start issue

I had the same issue with my Wilga - and after cleaning it is  

tolerable but not great.  I thought about removing the reducer, but  

left it.  How long has yours been off?  Is there any issue you can  

think of or have had with the step down valve off?  Seems like the  

best solution.



Herb

On Sep 24, 2007, at 8:03 AM, Genzlinger, Reade wrote:



[quote] 

 <ReadeG(at)Cairnwood.com>



 Steve:



 Had similar situation with the Wilga.  First we replaced several of  

 the

 air injectors that were sticking.  Second we had to replace the  

 "spider"

 or air distributer - lots of moisture damage (btw - Mort will probably

 never do that again).  Third we removed the step down valve which has

 improved starting 100%.  This item is not an issue with the Yaks.  The

 alignment of the brass plate in the air distributer is critical - I

 would check with Mort on that one.  Otherwise I would look for a stuck

 air injector.



 Reade Genzlinger

 Cairnwood Cooperative Corporation

 mailto:readeg(at)cairnwood.com

 215.914.0370



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ReadeG(at)Cairnwood.com
Guest

Posted: Mon Sep 24, 2007 9:47 am Post subject: Air start issue

Herb:



A bunch of Wilga owners have done this - we just took the innards of the

reducer out to avoid re-plumbing things and it works beautifully.  Been

doing it this way for 1 year.  I think the reducer was used to preserve

air for multiple start attempts since the storage bottles are so small.

Ours, if primed properly starts very easily and we've had no issues with

supply. 



Reade Genzlinger

Cairnwood Cooperative Corporation

mailto:readeg(at)cairnwood.com

215.914.0370

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mark.bitterlich(at)navy.m
Guest

Posted: Mon Sep 24, 2007 10:11 am Post subject: Air start issue

For the Russian made air start valves, be aware that there are two

types, those with the external manual lever and those without.  The

bottom half of the assy (where the solenoid is) can be swapped with a

new valve to retain this capability if desired. 



Mark Bitterlich

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Mozam

Joined: 24 Nov 2006
Posts: 85

Posted: Sun Sep 30, 2007 9:01 am Post subject: Re: Air start issue

Just an update on this problem, which I solved.  As is often the case, look at the simplest things first.



The -52W's and TW's have a UMA tach generator attached to the drive off the center of the air distributor.  This tach generator uses a washer (spacer) to maintain the proper clearance at the attach point to allow the air to flow correctly thru the distributor.



Long ago, I once accidentally installed the tach generator without this spacer.  Then when I hit the start button I could hear the air solenoid activate, but the prop never moved.  Luckily, I found the spacer when I opened the cowl, realized my error, and installed it correctly.  Then air start then worked fine.



So...I was suspicious of this spacer issue again, and pulled off the tach generator.  Lo and behold, I found TWO spacers installed!  I have no idea how this happened.  But, after removing one, the air start system is working fine again.



Apparently, this spacer is critical in allowing air to flow freely thru the air distributor.



I am VERY thankful I didn't have to mess with that air spider!!



-Steve

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