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engine roughness part 2

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pnicholson

Joined: 04 Jun 2011
Posts: 46

Posted: Sun Oct 30, 2011 3:26 pm Post subject: engine roughness part 2

Hi again,

        some weeks ago, I reported engine roughness on deceleration on

final. (Housai 6A).  In short, anything over 1000rpm and higher it

runs fairly smooth, the higher the revs the better.  But at idle, the

engine is very rough, panel shakes etc.

Since then a bit of exploration.

I confirmed that the primer is off and down.

On run-up rythmic poof of black smoke (assume unburnt fuel on one cylinder)

The oil screen filter was clear of metals (bit of goop), the gas

filter is clear of sediment and water.

We found that number nine cylinder is not firing properly and is just

luke warm after 10 minutes idle.  The plugs seem OK though the rear

plug had a bit of carbon between the gap on pluig.  We cleaned them

all up and reinserted, same problem.

So, my hangar mate things compression test is next (rings?)  Is there

anything else that I should be persuing?



Thanks,



Philip Nicholson



Nanchang - C-FEPN

mbeach(at)hartwigs.com.au
Guest

Posted: Sun Oct 30, 2011 3:53 pm Post subject: engine roughness part 2

Hi Phil, check your plug lead, We had a yak over here that had rubbed the

lead and would run rough and miss under certain

Situation. Fitted an aftermarket kit now runs like a dream.  When we

inspected the old lead we found arcing in the metal tubes on the bends. 



REGARDS 



MICHAEL BEACH

SERVICE MANAGER 

HARTWIGS

1 TRAVEL STOP WAY

LAVINGTON 

NSW 2641



PH 0260496044

FAX 0260496055

MOBILE 0427692366





--

pnicholson

Joined: 04 Jun 2011
Posts: 46

Posted: Sun Oct 30, 2011 4:53 pm Post subject: Re: engine roughness part 2

Hi Michael,

     thanks for the quick response.  But if there are two leads, two mags and two plugs for each cylinder, would it matter if one lead was shorting?

Is there any way to check for lead current? (novice )

Thanks,

Phil

pnicholson

Joined: 04 Jun 2011
Posts: 46

Posted: Sun Oct 30, 2011 5:04 pm Post subject: Re: engine roughness part 2

One last thing, the engine is more difficult to start than before.... typically takes 3-4 attempts and alot of fuel

Cheers,

Phil

cjpilot710(at)aol.com
Guest

Posted: Sun Oct 30, 2011 7:59 pm Post subject: engine roughness part 2

Philip,

 I think you should check that primer again.  If it is NOT  closing the valve at the bottom, it will pass fuel and give #9 cylinder way  to much fuel.  I've seen primers do just that.  They looked closed and  lock but were not.  You will get the very indications you are  describing.

  

 Also even with bad rings, a cylinder will fire and be almost as warm  as the others.  Doing a compression test is not hard, but may tell you if  #9 cylinder has bad valves or they are badly out of adjustment, or the rings are  totally shot.

  

 Jim "Pappy" Goolsby

  

  In a message dated 10/30/2011 7:26:19 P.M. Eastern Daylight Time,  pednicholson(at)gmail.com writes:

  	  Quote: 	
		  -->    Yak-List message posted by: Philip Nicholson    <pednicholson(at)gmail.com>



Hi again,

           some weeks ago, I reported engine roughness on deceleration on

final.    (Housai 6A).  In short, anything over 1000rpm and higher it

runs    fairly smooth, the higher the revs the better.  But at idle,    the

engine is very rough, panel shakes etc.

Since then a bit of    exploration.

I confirmed that the primer is off and down.

On run-up    rythmic poof of black smoke (assume unburnt fuel on one cylinder)

The oil    screen filter was clear of metals (bit of goop), the gas

filter is clear of    sediment and water.

We found that number nine cylinder is not firing    properly and is just

luke warm after 10 minutes idle.  The plugs seem    OK though the rear

plug had a bit of carbon between the gap on pluig.     We cleaned them

all up and reinserted, same problem.

So, my hangar mate    things compression test is next (rings?)  Is there

anything else that    I should be persuing?



Thanks,



Philip Nicholson



Nanchang -    ies  ay                 - MATRONICS WEB FORUMS               - List Contribution Web Site  p;                             



	


 [quote][b]

dsavarese0812(at)bellsout
Guest

Posted: Mon Oct 31, 2011 3:50 am Post subject: engine roughness part 2

Michael is right on the money.  Very likely a plug lead.  Trying to 

replace one lead can end up being a real nightmare.  If you'd like more 

information on the automotive conversion kit which Michael spoke about, 

you can read about it here.

http://www.yak-52.com/plug_conversion.htm



Dennis



A. Dennis Savarese

334-285-6263

334-546-8182 (cell)

Skype: Yakguy1

www.yak-52.com

On 10/30/2011 6:50 PM, Michael Beach wrote:

[quote] 



 Hi Phil, check your plug lead, We had a yak over here that had rubbed the

 lead and would run rough and miss under certain

 Situation. Fitted an aftermarket kit now runs like a dream.  When we

 inspected the old lead we found arcing in the metal tubes on the bends.



 REGARDS



 MICHAEL BEACH

 SERVICE MANAGER

 HARTWIGS

 1 TRAVEL STOP WAY

 LAVINGTON

 NSW 2641



 PH 0260496044

 FAX 0260496055

 MOBILE 0427692366





 --

mark.bitterlich(at)navy.m
Guest

Posted: Mon Oct 31, 2011 4:44 am Post subject: engine roughness part 2

Remove the spark plug lead from the spark plug.  Wet your finger and

grab hold of the small spring at the end.  Make sure you lick your

finger first. 



With your other hand, grab any handy part of bare metal on the airframe.

Stand clear of prop. 



Have observer standing by with audio level meter.  



When the engine first cranks have the observer record in Db the level of

the scream emitting from test subject. 



Note that after engine starts and RPM is increased, screams should  vary

in intensity according to engine RPM.  The reason for this is due to the

relatively weak spark used for starting compared to the more powerful

spark from the mag while running.  Additionally, spark energy tends to

increase with engine RPM, and with careful attention, the it will be

noted that the PITCH of test subjects scream will indeed vary with

engine RPM. 



Sorry.  Could not resist.  

Make sure you switch the spark plugs from this cylinder to another

cylinder just to eliminate any possible chance of bad plugs.  There are

indeed spark plug wire testers that will check for breakdown.  Most A&P

mechanics keep one in their box.  Failing that, try to get your hands on

a Megger and try that.  Pappy says check the primer again... which makes

sense.  Dennis and others suggest possible spark plugs leads.... also

VERY possible.  As to the engine having two spark plugs and wires .....

good point.  Until you remember that you don't often run a mag check at

idle.  



You have already stated that the engine seems to run OK at higher power

level settings.  You could have had one plug wire (or plug) bad at idle

for quite some time and just never knew it because the other one was

working. 



Run mag checks using mag switch at various power settings, from idle on

up and note what you see.  



If you think your primer is off ... turn it on and see if you notice a

difference.  The engine should run rougher at idle with it on, and

should clear up when you turn it off, check this.  



Do you have an intake clean kit?  The one with hoses that connect the

lower cylinders and then go to a drain to allow oil to drip out when the

engine is just sitting there?  If you do, just for the heck of it, check

to make sure it has no leaks, or something is broken.  



Of course run a compression check.   



Good luck



Mark

 

--

dsavarese0812(at)bellsout
Guest

Posted: Mon Oct 31, 2011 5:00 am Post subject: engine roughness part 2

My sides are hurting from laughing so hard Mark!  Great way to start off 

the work week.....with a good hard laugh.

Dennis



A. Dennis Savarese

334-285-6263

334-546-8182 (cell)

Skype: Yakguy1

www.yak-52.com

On 10/31/2011 7:42 AM, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 

64E wrote:

[quote] 



 Remove the spark plug lead from the spark plug.  Wet your finger and

 grab hold of the small spring at the end.  Make sure you lick your

 finger first.



 With your other hand, grab any handy part of bare metal on the airframe.

 Stand clear of prop.



 Have observer standing by with audio level meter.



 When the engine first cranks have the observer record in Db the level of

 the scream emitting from test subject.



 Note that after engine starts and RPM is increased, screams should  vary

 in intensity according to engine RPM.  The reason for this is due to the

 relatively weak spark used for starting compared to the more powerful

 spark from the mag while running.  Additionally, spark energy tends to

 increase with engine RPM, and with careful attention, the it will be

 noted that the PITCH of test subjects scream will indeed vary with

 engine RPM.



 Sorry.  Could not resist.

 Make sure you switch the spark plugs from this cylinder to another

 cylinder just to eliminate any possible chance of bad plugs.  There are

 indeed spark plug wire testers that will check for breakdown.  Most A&P

 mechanics keep one in their box.  Failing that, try to get your hands on

 a Megger and try that.  Pappy says check the primer again... which makes

 sense.  Dennis and others suggest possible spark plugs leads.... also

 VERY possible.  As to the engine having two spark plugs and wires .....

 good point.  Until you remember that you don't often run a mag check at

 idle.



 You have already stated that the engine seems to run OK at higher power

 level settings.  You could have had one plug wire (or plug) bad at idle

 for quite some time and just never knew it because the other one was

 working.



 Run mag checks using mag switch at various power settings, from idle on

 up and note what you see.



 If you think your primer is off ... turn it on and see if you notice a

 difference.  The engine should run rougher at idle with it on, and

 should clear up when you turn it off, check this.



 Do you have an intake clean kit?  The one with hoses that connect the

 lower cylinders and then go to a drain to allow oil to drip out when the

 engine is just sitting there?  If you do, just for the heck of it, check

 to make sure it has no leaks, or something is broken.



 Of course run a compression check.



 Good luck



 Mark



 --

tigeryak18t

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

Posted: Mon Oct 31, 2011 5:11 am Post subject: engine roughness part 2

EXCELLENT MarkSorry but you might have heard my laugh from the other side of the ocean!!! Hope it did not wake you up !!!

I know a few people who can play the tester role here.

Have a very good day

  



Didier



2011/10/31 Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>

  [quote]--> Yak-List message posted by: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>

   

 Remove the spark plug lead from the spark plug.  Wet your finger and

 grab hold of the small spring at the end.  Make sure you lick your

 finger first.

 

 With your other hand, grab any handy part of bare metal on the airframe.

 

 

 Stand clear of prop.

 

 Have observer standing by with audio level meter.

 

 When the engine first cranks have the observer record in Db the level of

 the scream emitting from test subject.

 

 Note that after engine starts and RPM is increased, screams should  vary

 in intensity according to engine RPM.  The reason for this is due to the

 relatively weak spark used for starting compared to the more powerful

 spark from the mag while running.  Additionally, spark energy tends to

 increase with engine RPM, and with careful attention, the it will be

 noted that the PITCH of test subjects scream will indeed vary with

 engine RPM.

 

 Sorry.  Could not resist.

 

 

 Make sure you switch the spark plugs from this cylinder to another

 cylinder just to eliminate any possible chance of bad plugs.  There are

 indeed spark plug wire testers that will check for breakdown.  Most A&P

 mechanics keep one in their box.  Failing that, try to get your hands on

 a Megger and try that.  Pappy says check the primer again... which makes

 sense.  Dennis and others suggest possible spark plugs leads.... also

 VERY possible.  As to the engine having two spark plugs and wires .....

 good point.  Until you remember that you don't often run a mag check at

 idle.

 

 You have already stated that the engine seems to run OK at higher power

 level settings.  You could have had one plug wire (or plug) bad at idle

 for quite some time and just never knew it because the other one was

 working.

 

 Run mag checks using mag switch at various power settings, from idle on

 up and note what you see.

 

 If you think your primer is off ... turn it on and see if you notice a

 difference.  The engine should run rougher at idle with it on, and

 should clear up when you turn it off, check this.

 

 Do you have an intake clean kit?  The one with hoses that connect the

 lower cylinders and then go to a drain to allow oil to drip out when the

 engine is just sitting there?  If you do, just for the heck of it, check

 to make sure it has no leaks, or something is broken.

 

 Of course run a compression check.

 

 Good luck

 

 Mark

 

 

 

 --

_________________
Didier Tiger YAK18T
Member of Commemorative Air Force
French Wing

pnicholson

Joined: 04 Jun 2011
Posts: 46

Posted: Fri Nov 04, 2011 5:50 am Post subject: engine roughness part 2 (fixed)

So....

messed with manual primer, very little draw/resistance. In the process though heard gas dripping on the hangar floor.  Upon investigation, it was dripping out of an intake drain coupling.  The coupling, while appearing seated, had backed off completely.  I tightened it up and replaced the seals in the primer (thanks NAPA )

Conducted a run up last night and the engine runs well again.

Only drag is I'll never know if it was the leaking intake drain or the primer  (probably primer or both)

Thanks very much to all those who chipped in with their helpful advice and humour.



Phil

C-FEPN

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