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engine turning backward at shutdown

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Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Tue Jan 12, 2010 7:28 am Post subject: engine turning backward at shutdown

Well, my old nemesis is back. I had thought it was a summertime thing but it is here again!

 I flew for about an hour yesterday. I had the radiator taped for the cold weather and the temp was running at about 200-210 degrees on the coolant (CHT) and 190 on the oil temp during cruise. At engine shutdown I reduced the idle to about 1400 rpm and turned off the key,shuting down both mags at once. I forgot to do one at a time. The engine shut down then turned about 4-5 blades backward. Well, that gave me the RA (red ass) so I tried it again. The next time it turned backwards at least 4- 5 complete engine revolutions. I thought I might back into my parking spot! One more shot on the start, oil pressure looked normal then it shut down normally. Now I already know that I am the only guy in the country to have this problem but still, it is a bit perplexing. Other factors 1) my regular grade fuel is about a month old (2) the cht was a little warmer on shutdown although well in the green.( 200) The engine does not do this all the time and usually switching to 93 octane seems to stop this (which I will do) even though this engine is supposed to burn regular. In each of the prior cases of this happening (about 4 times),I have pulled the valve covers and checked the valve clearances to insure no air in the lifters resulting in possible cam damage. The clearances have all been normal, no metal in the filter, and no metal in the oil sampling. The engine has 230 hts tt.

  One other thing on a different subject,. the oil filter. I am one of two guys in the country (according to Lockwood) to have an oil filter almost unspin itself .This statement is not really true as two other guys on the Team Kitfox forum have had the same thing happen. One had a destroyed engine because of it.

  During the course of a normal oil change I was trying to get the right tool to loosen my oil filter. It is a tight fit in there. I was told that they can be a bear to remove and also told there is no reason to safety wire the filter.(per my Rotax school) Well ,that's not true!  I grabbed the filter with my hand to put the oil filter remover on and the filter just spun with little to no pressure! It could have come off or loosened enough in flight to loose all the oil! On the previous oil change, I had followed the oil change procedure,including filter torquing, to the letter as I had the SI right in front of me. I triple checked the torque!

  I now safety wire the oil filter with a large clamp around it and also torque mark it.

  I know I have mentioned this before but for new members you might want to keep a check on yours.

                                                                    Dick Maddux

                                                                    912 UL

                                                                    Milton,Fl

  [quote][b]

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Tue Jan 12, 2010 9:40 am Post subject: Re: engine turning backward at shutdown

[quote="Dick Maddux"]Well, my old nemesis is back. I had thought it was a summertime thing but it is here again!

 I flew for about an hour yesterday. I had the radiator taped for the cold weather and the temp was running at about 200-210 degrees on the coolant (CHT) and 190 on the oil temp during cruise. At engine shutdown I reduced the idle to about 1400 rpm and turned off the key,shuting down both mags at once. I forgot to do one at a time. The engine shut down then turned about 4-5 blades backward. Well, that gave me the RA (red ass) so I tried it again. The next time it turned backwards at least 4- 5 complete engine revolutions. I thought I might back into my parking spot! One more shot on the start, oil pressure looked normal then it shut down normally. Now I already know that I am the only guy in the country to have this problem but still, it is a bit perplexing. Other factors 1) my regular grade fuel is about a month old (2) the cht was a little warmer on shutdown although well in the green.( 200) The engine does not do this all the time and usually switching to 93 octane seems to stop this (which I will do) even though this engine is supposed to burn regular. In each of the prior cases of this happening (about 4 times),I have pulled the valve covers and checked the valve clearances to insure no air in the lifters resulting in possible cam damage. The clearances have all been normal, no metal in the filter, and no metal in the oil sampling. The engine has 230 hts tt.

  One other thing on a different subject,. the oil filter. I am one of two guys in the country (according to Lockwood) to have an oil filter almost unspin itself .This statement is not really true as two other guys on the Team Kitfox forum have had the same thing happen. One had a destroyed engine because of it.

  During the course of a normal oil change I was trying to get the right tool to loosen my oil filter. It is a tight fit in there. I was told that they can be a bear to remove and also told there is no reason to safety wire the filter.(per my Rotax school) Well ,that's not true!  I grabbed the filter with my hand to put the oil filter remover onï¿½and the filter just spun with little to no pressure! It could have come off or loosened enough in flight to loose all the oil! On the previous oil change, I had followed the oil change procedure,including filter torquing, to the letter as I had the SI right in front of me. I triple checked the torque!

  I now safety wire the oil filter with a large clamp around it and also torque mark it.

  I know I have mentioned this before but for new members you might want to keep a check on yours.

            ï¿½           ï¿½            ï¿½           ï¿½           ï¿½      Dick Maddux

            ï¿½           ï¿½            ï¿½           ï¿½           ï¿½      912 UL

            ï¿½           ï¿½            ï¿½           ï¿½           ï¿½      Milton,Fl

   	  Quote: 	
		  [b] 	




Sounds like cheap gas to me. Just because it says Bill & Ted's Excellent gas on the pump doesn't mean it's good. I got a tank of some cheap stuff a while back (still a 91 octane premium gas) and I got the occasional dieseling on shutdown too (912ULS). I drained the tank and tried some gas from a different station with no problems.



Try a different station and/or brand of regular gas and see what happens there. The fact that higher octane gas fixes the problem would seem to be the smoking gun. 



On the oil filter, Rotax says to go 3/4 of a turn down after the gasket makes contact with the face of the pump. That has never been tight enough with any filter I've ever used including the Rotax filter. Every time there's a substantial leak after the initial run up (again even with the Rotax filter). I've checked the face for flatness and evenness of contact of the filter to the face and it looks ok to me. It's just not enough tightness.



Now I go at least a full turn and no more than 1 1/4 turns and never see leaks.



Getting the old filter off is a struggle no way around it. The regular wrench that fits onto the end of the filter isn't enough (it just strips) even when I was tightening it down only 3/4 turn.



I have to use the pliars-style wrench from Pep-boys that destroys the filter to get it loose (with strong support underneath the filter with the other hand to prevent strong downward bending pressure on the oil pump).....



LS

_________________
LS
Titan II SS

flyadive(at)gmail.com
Guest

Posted: Tue Jan 12, 2010 3:13 pm Post subject: engine turning backward at shutdown

Dick:

  

 I am new to ROTAX engines but the standard way of shutting down Lycoming and Continental engines is to Pull The Mixture, not shut off the Mags.  As long as there is Heat, Fuel Air and something close to timing the mixture getting into the cylinder will ignite.  If there is not proper timing (see above) it could ignite as it is coming up to the compression and Kick Back, as in your case.

   

 So, my questions to the group are:  

 1 - Is just shutting off the Mags the normal way of shutting down a ROTAX?  

 2 - Is 1400 RPM the normal shut down RPM?

  

 Barry

 On Tue, Jan 12, 2010 at 10:27 AM, <catz631(at)aol.com (catz631(at)aol.com)> wrote:

 [quote]  Well, my old nemesis is back. I had thought it was a summertime thing but it is here again!

 I flew for about an hour yesterday. I had the radiator taped for the cold weather and the temp was running at about 200-210 degrees on the coolant (CHT) and 190 on the oil temp during cruise. At engine shutdown I reduced the idle to about 1400 rpm and turned off the key,shuting down both mags at once. I forgot to do one at a time. The engine shut down then turned about 4-5 blades backward. 

 

[b]

rlborger(at)mac.com
Guest

Posted: Tue Jan 12, 2010 3:39 pm Post subject: engine turning backward at shutdown

Barry,



There is no mixture control on a standard Rotax engine installation.  The shutdown method recommended in the book is to set the throttle to idle and turn off the ignition switches.  The Rotax doesn't really have "mags" as it has a CDI (Capacitive Discharge Ignition).  Though most folks still call them "mag" switches from long habit with aircraft engines.

Ignition timing is controlled by a set of powerful magnets fixed on the flywheel as they pass induction pickups fixed on the engine case.  It's all fixed and can not be altered.

1400 RPM is slower than the recommended 1800 RPM idle.  If you idle very much below 1800 RPM you will beat the reduction gears to death in short order.

Dick,

Sounds like a bad batch of gasoline to me, well below the recommended 91 octane, that is igniting under compression in a hot engine.  Your experience with higher octane making the dieseling go away sure seems to point to it anyway.  I'm surprised there are no problems with engine knock/ping.



 Bob Borger

Europa Kit #A221 N914XL, XS Mono, Intercooled 914, Airmaster C/S

http://www.europaowners.org/N914XL

Aircraft Flying!

3705 Lynchburg Dr.

Corinth, TX  76208

Home:  940-497-2123

Cel:  817-992-1117





 

 

On Jan 12, 2010, at 17:12, FLYaDIVE wrote:

 	  Quote: 	
		  Dick:

  

 I am new to ROTAX engines but the standard way of shutting down Lycoming and Continental engines is to Pull The Mixture, not shut off the Mags.  As long as there is Heat, Fuel Air and something close to timing the mixture getting into the cylinder will ignite.  If there is not proper timing (see above) it could ignite as it is coming up to the compression and Kick Back, as in your case.

   

 So, my questions to the group are:  

 1 - Is just shutting off the Mags the normal way of shutting down a ROTAX?  

 2 - Is 1400 RPM the normal shut down RPM?

  

 Barry

 On Tue, Jan 12, 2010 at 10:27 AM, <catz631(at)aol.com (catz631(at)aol.com)> wrote:

  	  Quote: 	
		    Well, my old nemesis is back. I had thought it was a summertime thing but it is here again!

 I flew for about an hour yesterday. I had the radiator taped for the cold weather and the temp was running at about 200-210 degrees on the coolant (CHT) and 190 on the oil temp during cruise. At engine shutdown I reduced the idle to about 1400 rpm and turned off the key,shuting down both mags at once. I forgot to do one at a time. The engine shut down then turned about 4-5 blades backward. 

 





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href="http://forums.matronics.com/">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/contribution

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Jan 12, 2010 5:59 pm Post subject: engine turning backward at shutdown

You may have a slightly rich condition which allows for detonation on stopping causing the engine to run backward.  I’ve seen it in some cars and increasing the octane has always cured it.  

   

Noel  

       

From: owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] On Behalf Of catz631(at)aol.com

 Sent: January 12, 2010 11:58 AM

 To: rotaxengines-list(at)matronics.com

 Subject: engine turning backward at shutdown  

  

  

     

Well, my old nemesis is back. I had thought it was a summertime thing but it is here again!  

    

I flew for about an hour yesterday. I had the radiator taped for the cold weather and the temp was running at about 200-210 degrees on the coolant (CHT) and 190 on the oil temp during cruise. At engine shutdown I reduced the idle to about 1400 rpm and turned off the key,shuting down both mags at once. I forgot to do one at a time. The engine shut down then turned about 4-5 blades backward. Well, that gave me the RA (red ass) so I tried it again. The next time it turned backwards at least 4- 5 complete engine revolutions. I thought I might back into my parking spot! One more shot on the start, oil pressure looked normal then it shut down normally. Now I already know that I am the only guy in the country to have this problem but still, it is a bit perplexing. Other factors 1) my regular grade fuel is about a month old (2) the cht was a little warmer on shutdown although well in the green.( 200) The engine does not do this all the time and usually switching to 93 octane seems to stop this (which I will do) even though this engine is supposed to burn regular. In each of the prior cases of this happening (about 4 times),I have pulled the valve covers and checked the valve clearances to insure no air in the lifters resulting in possible cam damage. The clearances have all been normal, no metal in the filter, and no metal in the oil sampling. The engine has 230 hts tt.  

    

 One other thing on a different subject,. the oil filter. I am one of two guys in the country (according to Lockwood) to have an oil filter almost unspin itself .This statement is not really true as two other guys on the Team Kitfox forum have had the same thing happen. One had a destroyed engine because of it.  

    

 During the course of a normal oil change I was trying to get the right tool to loosen my oil filter. It is a tight fit in there. I was told that they can be a bear to remove and also told there is no reason to safety wire the filter.(per my Rotax school) Well ,that's not true!  I grabbed the filter with my hand to put the oil filter remover on and the filter just spun with little to no pressure! It could have come off or loosened enough in flight to loose all the oil! On the previous oil change, I had followed the oil change procedure,including filter torquing, to the letter as I had the SI right in front of me. I triple checked the torque!  

    

 I now safety wire the oil filter with a large clamp around it and also torque mark it.  

    

 I know I have mentioned this before but for new members you might want to keep a check on yours.  

    

                                                                   Dick Maddux  

    

                                                                   912 UL  

    

                                                                   Milton,Fl  

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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Jan 12, 2010 6:03 pm Post subject: engine turning backward at shutdown

I had a similar experience with gasoline in my Subaru (car).  I bought gas

at really low prices at a reserve in Nova Scotia.  To say the car didn't

like it would be an understatement.  It burped and backfired chugged and did

the whole gambit before I was able to get some "Brand Name" gas into the

tank.  That doesn't sound too bad until you take into consideration the EFI

is supposed to comphensate for all that kind of thing.  Your 912 without the

EFI and associated paraphernalia wouldn't stand a chance with cheap or low

octane fuel.



Noel



Sounds like cheap gas to me. Just because it says Bill & Ted's Excellent gas

on the pump doesn't mean it's good. I got a tank of some cheap stuff a while

back (still a 91 octane premium gas) and I got the occasional dieseling on

shutdown too (912ULS). I drained the tank and tried some gas from a

different station with no problems.



Try a different station and/or brand of regular gas and see what happens

there. The fact that higher octane gas fixes the problem would seem to be

the smoking gun. 



On the oil filter, Rotax says to go 3/4 of a turn down after the gasket

makes contact with the face of the pump. That has never been tight enough

with any filter I've ever used including the Rotax filter. Every time

there's a substantial leak after the initial run up (again even with the

Rotax filter). 



Now I go at least a full turn and no more than 1 1/4 turns and never see

leaks.



Getting the old filter off is a struggle no way around it. The regular

wrench that fits onto the end of the filter isn't enough (it just strips)

even when I was tightening it down only 3/4 turn.



I have to use the pliars-style wrench from Pep-boys that destroys the filter

to get it loose (with strong support underneath the filter with the other

hand to prevent strong downward bending pressure on the oil pump).....



LS



--------

LS

Titan II SS





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 81181#281181

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Jan 12, 2010 6:55 pm Post subject: engine turning backward at shutdown

Yes, because there is no mixture control on the bing carbs...  BTW some early Cubs had their mixture controls wired in place under the cowl so again they had to be stopped by shutting down the mags.  

   

Noel  

     

From: owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] On Behalf Of FLYaDIVE

 Sent: January 12, 2010 7:43 PM

 To: rotaxengines-list(at)matronics.com

 Subject: Re: engine turning backward at shutdown  

  

     

Dick:  

    

   

    

I am new to ROTAX engines but the standard way of shutting down Lycoming and Continental engines is to Pull The Mixture, not shut off the Mags.  As long as there is Heat, Fuel Air and something close to timing the mixture getting into the cylinder will ignite.  If there is not proper timing (see above) it could ignite as it is coming up to the compression and Kick Back, as in your case.  

    

   

    

So, my questions to the group are:    

    

1 - Is just shutting off the Mags the normal way of shutting down a ROTAX?    

    

2 - Is 1400 RPM the normal shut down RPM?  

    

   

    

Barry  

    

On Tue, Jan 12, 2010 at 10:27 AM, <catz631(at)aol.com (catz631(at)aol.com)> wrote:      

Well, my old nemesis is back. I had thought it was a summertime thing but it is here again!  

    

I flew for about an hour yesterday. I had the radiator taped for the cold weather and the temp was running at about 200-210 degrees on the coolant (CHT) and 190 on the oil temp during cruise. At engine shutdown I reduced the idle to about 1400 rpm and turned off the key,shuting down both mags at once. I forgot to do one at a time. The engine shut down then turned about 4-5 blades backward.   

  

  

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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Wed Jan 13, 2010 5:30 am Post subject: engine turning backward at shutdown

It is good to hear that some of you guys have had the same problem. I figured I wasn't the only one! I am going to pour in some octane booster in my remaining gas. I did that once before and it seemed to work. The gas I originally purchased came from Shell but I guess, as all the magazine articles suggest, it doesn't last long anymore before it looses its octane.

                                                                          Dick Maddux

                                                                          Rotax 912

  [quote][b]

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Jan 13, 2010 10:06 am Post subject: engine turning backward at shutdown

RON of ethanol is 116 as it evaporates form your gas the RON will plummet!  

   

Noel  

       

From: owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] On Behalf Of catz631(at)aol.com

 Sent: January 13, 2010 9:59 AM

 To: rotaxengines-list(at)matronics.com

 Subject: Re: engine turning backward at shutdown  

  

  

     

It is good to hear that some of you guys have had the same problem. I figured I wasn't the only one! I am going to pour in some octane booster in my remaining gas. I did that once before and it seemed to work. The gas I originally purchased came from Shell but I guess, as all the magazine articles suggest, it doesn't last long anymore before it looses its octane.  

    

                                                                         Dick Maddux  

    

                                                                         Rotax 912  

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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Wed Jan 13, 2010 12:50 pm Post subject: Re: engine turning backward at shutdown

[quote="Dick Maddux"]It is good to hear that some of you guys have had the same problem. I figured I wasn't the only one! I am going to pour in some octane booster in my remaining gas. I did that once before and it seemed to work. The gas I originally purchased came from Shell but I guess, as all the magazine articles suggest, it doesn't last long anymore before it looses its octane.

            ï¿½           ï¿½            ï¿½           ï¿½           ï¿½            Dick Maddux

            ï¿½           ï¿½            ï¿½           ï¿½           ï¿½            Rotax 912

   	  Quote: 	
		  [b] 	




Since I use E10 now (that's all that's available besides 100LL), I don't let gas sit in the tank much longer than about 2 weeks at the very outside. And usually I start robbing gas out of the plane with the siphon once a week goes by and I don't get to fly, and it goes in the pickup.



Personally, if I didn't remember how old the gas actually was, I'd drain it out and burn it in the veehickle (to take me to the gas station for new gas for the plane)....



LS

_________________
LS
Titan II SS

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Jan 13, 2010 5:41 pm Post subject: engine turning backward at shutdown

When you leave ethanol gas sitting in your plane if you have epoxy resin

tanks that is when you can start having problems with your tanks being

dissolved by the ethanol.  



The part about ethanol evaporating you already know.  The longer the gas

sits in the plane the more moisture it can remove from the air.  The problem

with that is it also increases  your chances of a phase separation when the

fuel cools at altitude.  For what it's worth I'd drain what fuel is in the

tanks after every flight and only use as fresh as I could get fuel in the

plane.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

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