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Throttle Open on Shutdown ?

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Ttail

Joined: 24 Jun 2013
Posts: 120

Posted: Mon Jun 08, 2015 7:10 pm Post subject: Throttle Open on Shutdown ?

What is the reasoning behind Opening the Throttle to Full Open on engine Shut Down ?

tigeryak18t

Joined: 26 Sep 2009
Posts: 233
Location: PARIS FRANCE

Posted: Mon Jun 08, 2015 9:13 pm Post subject: Throttle Open on Shutdown ?

I was doing this and it was working fine. Supposed to prepare the next start with a cloud of gas. But my mechanic told me not to do it. The risk is that the fuel may wash oil in the cylinders and could damage the internal surface of the cylinders.

Where is the truth?

Since then I stopped opening the throttle when stopping my motor!!!

Still running it 60% during 20sec for two reasons oil and cylinders temperature homogenization.



Didier Blouzard

+33 6 5184 4802



 	  Quote: 	
		   Le 9 juin 2015 Ã  05:10, Ttail <ttail(at)internode.on.net> a Ã©crit :

 

 

 

 What is the reasoning behind Opening the Throttle to Full Open on engine Shut Down ?

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=443258#443258

_________________
Didier Tiger YAK18T
Member of Commemorative Air Force
French Wing

drc(at)wscare.com
Guest

Posted: Tue Jun 09, 2015 6:41 am Post subject: Throttle Open on Shutdown ?

I believe the reason is to drive the oil scavenge pump to return as much oil out of the case as possible to the tank.  This reduces the risk of hydraulic lock on the next start up.

Herb Coussons

drc(at)wscare.com



 	  Quote: 	
		   On Jun 8, 2015, at 10:10 PM, Ttail <ttail(at)internode.on.net> wrote:

 

 

 

 What is the reasoning behind Opening the Throttle to Full Open on engine Shut Down ?

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=443258#443258

Viperdoc

Joined: 19 Apr 2014
Posts: 484
Location: 08A

Posted: Tue Jun 09, 2015 1:48 pm Post subject: Throttle Open on Shutdown ?

That is the reason for savaging the engine (at) 70% X 15-20 sec. Opening the throttle at idle/mag shutoff is to prevent post detonation kick backs. Does it cloud the cylinders and cause washout of oil on the cylinder walls I don't know.

It does cut down on kick backs for me. Yes I shutdown with cylinder temps at 160. That as measured on #3. Who knows what the other cylinders are at short of jumping out and measuring the CHT with the laser.

Doc

Sent from my iPad

 	  Quote: 	
		   On Jun 9, 2015, at 9:41 AM, Dr. Herbert Coussons <drc(at)wscare.com> wrote:

 I believe the reason is to drive the oil scavenge pump to return as much oil out of the case as possible to the tank.  This reduces the risk of hydraulic lock on the next start up.

 Herb Coussons

 drc(at)wscare.com

> On Jun 8, 2015, at 10:10 PM, Ttail <ttail(at)internode.on.net> wrote:

> 

> 

> 

> What is the reasoning behind Opening the Throttle to Full Open on engine Shut Down ?

> 

> 

> 

> 

> Read this topic online here:

> 

> http://forums.matronics.com/viewtopic.php?p=443258#443258

> 

> 

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> 

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>

_________________
Viperdoc

mark.bitterlich(at)navy.m
Guest

Posted: Tue Jun 09, 2015 2:21 pm Post subject: Throttle Open on Shutdown ?

Concur on scavenging which is a common procedure for various dry sump engines, including a Lycoming GSO-480.

Opening the throttle on shutdown is something I would love to see an explanation in writing on.  Interpreted from the original Russian I mean!   There is a ton of urban legend on this one.  The explanation I was given is that it helps to seal the rings to reduce oil creeping past.  Which was also accompanied by the statement that once the prop stopped moving, you should not touch it or it will "unseal" the rings.

Another piece of advice was to turn the prop BACKWARDS directly after shutdown to help seal the ball check valve in the oil pump to help prevent leakage.   I tried that one and it actually seemed to make a difference, but that was purely subjective.

Bottom line, lots of explanations... and I am not sure which one is actually correct... but I do it anyway.  

Mark

________________________________

From: owner-yak-list-server(at)matronics.com [owner-yak-list-server(at)matronics.com] on behalf of Roger Kemp [f16viperdoc(at)me.com]

Sent: Tuesday, June 09, 2015 5:47 PM

To: yak-list(at)matronics.com

Subject: Re: Throttle Open on Shutdown ?

That is the reason for savaging the engine (at) 70% X 15-20 sec. Opening the throttle at idle/mag shutoff is to prevent post detonation kick backs. Does it cloud the cylinders and cause washout of oil on the cylinder walls I don't know.

It does cut down on kick backs for me. Yes I shutdown with cylinder temps at 160. That as measured on #3. Who knows what the other cylinders are at short of jumping out and measuring the CHT with the laser.

Doc

Sent from my iPad

 	  Quote: 	
		   On Jun 9, 2015, at 9:41 AM, Dr. Herbert Coussons <drc(at)wscare.com> wrote:

 I believe the reason is to drive the oil scavenge pump to return as much oil out of the case as possible to the tank.  This reduces the risk of hydraulic lock on the next start up.

 Herb Coussons

 drc(at)wscare.com

> On Jun 8, 2015, at 10:10 PM, Ttail <ttail(at)internode.on.net> wrote:

>

> 

>

> What is the reasoning behind Opening the Throttle to Full Open on engine Shut Down ?

>

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p=443258#443258

>

>

PS

Joined: 08 Sep 2006
Posts: 84
Location: Texas

Posted: Tue Jun 09, 2015 2:46 pm Post subject: Throttle Open on Shutdown ?

Mark, 

 

  By moving your prop backwards slightly, it reverses or releives the pressure on the check valve at the oil pump. I had good results.

  

 

  Phil

 

 

  --

_________________
Phil

jblake207(at)comcast.net
Guest

Posted: Tue Jun 09, 2015 3:18 pm Post subject: Throttle Open on Shutdown ?

FWIW... I quit the procedure of the high rpm run just prior to shutdown about 8 months ago... Since then I've seen much less oil drain out of the exhaust stacks and intake drains... And haven't had one hydrostatic lock. No scientific data but...

Sent from my Verizon Wireless 4G LTE DROID

Roger Kemp <f16viperdoc(at)me.com> wrote:

--> Yak-List message posted by: Roger Kemp <f16viperdoc(at)me.com>

That is the reason for savaging the engine (at) 70% X 15-20 sec. Opening the throttle at idle/mag shutoff is to prevent post detonation kick backs. Does it cloud the cylinders and cause washout of oil on the cylinder walls I don't know.

It does cut down on kick backs for me. Yes I shutdown with cylinder temps at 160. That as measured on #3. Who knows what the other cylinders are at short of jumping out and measuring the CHT with the laser.

Doc

Sent from my iPad

 	  Quote: 	
		   On Jun 9, 2015, at 9:41 AM, Dr. Herbert Coussons <drc(at)wscare.com> wrote:

 --> Yak-List message posted by: "Dr. Herbert Coussons" <drc(at)wscare.com>

 I believe the reason is to drive the oil scavenge pump to return as much oil out of the case as possible to the tank.  This reduces the risk of hydraulic lock on the next start up.

 Herb Coussons

 drc(at)wscare.com

> On Jun 8, 2015, at 10:10 PM, Ttail <ttail(at)internode.on.net> wrote:

> 

> --> Yak-List message posted by: "Ttail" <ttail(at)internode.on.net>

> 

> What is the reasoning behind Opening the Throttle to Full Open on engine Shut Down ?

> 

> 

> 

> 

> Read this topic online here:

> 

> http://forums.matronics.com/viewtopic.php?p=443258#443258

> 

> 

> 

> 

> 

> 

> 

> 

> 

> 

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Bill vH

Joined: 26 Oct 2010
Posts: 8

Posted: Wed Jun 10, 2015 10:29 am Post subject: Re: Throttle Open on Shutdown ?

 	  PS wrote: 	
		  Mark, 

 

  By moving your prop backwards slightly, it reverses or releives the pressure on the check valve at the oil pump. I had good results.

  

 

  Phil

 

 

  -- 	




Actually Phil, I would think that it may slightly pressurize the check valve, increasing its limited effectiveness. Just remember the orientation and flow direction of the valve.

I think I'll give it a try.

Bill vH

PS

Joined: 08 Sep 2006
Posts: 84
Location: Texas

Posted: Wed Jun 10, 2015 10:33 am Post subject: Throttle Open on Shutdown ?

You are correct, long day at work and brain fart...

Thanks

Phil



Securities offered through Summit Brokerage Services Inc., Member FINRA, SIPC. Advisory services offered through Summit Financial Group Inc., a Registered Investment Advisor.Sent from my IPad.



On Jun 10, 2015, at 1:29 PM, Bill vH <billvh(at)beanddi.com (billvh(at)beanddi.com)> wrote:

[quote]--> Yak-List message posted by: "Bill vH" <billvh(at)beanddi.com (billvh(at)beanddi.com)>

PS wrote:

 	  Quote: 	
		  Mark, 



  By moving your prop backwards slightly, it reverses or releives the pressure on the check valve at the oil pump. I had good results.

  Phil

  --

	




Actually Phil, I would think that it may slightly pressurize the check valve, increasing its limited effectiveness. Just remember the orientation and flow direction of the valve.

I think I'll give it a try.

Bill vH





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=443356#443356



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[b]

_________________
Phil

av8ter

Joined: 25 Apr 2015
Posts: 27

Posted: Thu Jun 11, 2015 7:40 pm Post subject: Re: Throttle Open on Shutdown ?

prop.....2 say backwards and 1 says forward....which is it?

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