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Yak 50 priming drip

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john(at)johnalber.com
Guest

Posted: Sat Aug 04, 2007 7:31 am Post subject: Yak 50 priming drip

When I prime my 50, fuel drips from the airbox under the carb.

Dennis thinks this may be normal on 50s and not show up on 52s

because they are level. Any other 50 or 55 drivers have this

experience?



Thanks



John Alber



John Alber

john(at)johnalber.com

314-259-2144

jan.mevis(at)informavia.b
Guest

Posted: Sat Aug 04, 2007 8:19 am Post subject: Yak 50 priming drip

I have had it when priming too much. Be careful when priming. You may start

a fire. I have already started a fire once. I was very lucky to have friends

with fire extinguishers in the neighborhood. No damage thanks to their rapid

intervention! The fire I started, was entirely my own fault, being

unexperienced with the Yak. 



IMHO, when the engine does not start easily, there's some problem. For best

practices, try to have someone with a fire extinguisher in the neighborhood

when starting. Of course, this is not always possible.



Jan Mevis

YK 50 RA2005K



--

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Sat Aug 04, 2007 8:31 am Post subject: Re: Yak 50 priming drip

I have never seen that on my -50...at least not that I can remember. Does it happen with just one squirt or after a few? 



Did you just recently buy that -50 and if so, from whom..if you do not mind me asking.

brian-1927(at)lloyd.com
Guest

Posted: Sat Aug 04, 2007 1:13 pm Post subject: Yak 50 priming drip

On Aug 4, 2007, at 11:27 AM, John Alber wrote:



 	  Quote: 	
		   



 When I prime my 50, fuel drips from the airbox under the carb.

 Dennis thinks this may be normal on 50s and not show up on 52s

 because they are level. Any other 50 or 55 drivers have this

 experience?


	


Perhaps it is a good idea to think about what is happening when you  

prime your engine so you have an idea what to expect and what can  

happen.



The Housai and M14 engines inject the primer at the top of the  

supercharger housing. (I think that the idea was that the gasoline on  

the large surface area of the supercharger impeller would vaporize  

better, especially with the supercharger rotating as the engine  

starts.) Regardless, if you put a lot of prime in there it is going  

to drip to the bottom of the housing where it will either go into the  

intake risers for the lower cylinders and/or, if it flows down the  

blades of the impeller toward the the aft central part, out through  

the carburetor. If it does that it will drip out the carb into the  

airbox and then out the bottom of the air box.



To be honest, if you have fuel dripping out of the airbox you have  

probably put in too much prime. It is a good idea to have someone  

rotate the prop one blade for every shot of primer to better  

distribute the prime around in the supercharger housing. In that case  

there is less chance it will find its way out through the carburetor  

or pool in the intake riser tubes. BTW, a big slug of primer in the  

intake riser tubes can be sucked up and cause a hydraulic lock just  

like a slug of oil will.



So, if your engine doesn't fire after about three blades, you did  

something wrong. Continuing to pump in primer is probably not the  

best solution unless you know for a fact that you are under primed.

--

Brian Lloyd                         3191 Western Drive

brian HYPHEN 1927 AT lloyd DOT com    Cameron Park, CA 95682

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry



PGP key ID:          12095C52A32A1B6C

PGP key fingerprint: 3B1D BA11 4913 3254 B6E0  CC09 1209 5C52 A32A 1B6C

viperdoc(at)mindspring.co
Guest

Posted: Sat Aug 04, 2007 6:35 pm Post subject: Yak 50 priming drip

Jon,

How many strokes are you injecting into the supercharger. The primer line

attaches to the top of the supercharger the same as on the 52. Everything

said earlier on the list is correct. If you charge the system to much some

fuel may run out of the carburetor throat.  The is a lot of fuel if your

priming is on the cylinder side (on the 50, the primer is rotated inboard.

To pressurize the carb/fuel system, the primer plunger is rotated out board

on the 50). Just so we know, and not to ask a stupid question either. But

are you priming the supercharger or are you pressurizing the system?

I have seen fuel running down the throat of my carb after I scavenge the

system. I see the blue drops at the back of my carb. It really was not

coming from my carb though. It was coming from the overflow vent on the left

lower side of the fuel pump. That was the first sign that I had seals in my

fuel pump diaphragm going bad. The second sign was that oil began to drip

out of the overflow drain pipe. I could not find the source for the fuel and

then the oil drip which was very slow. And aggravating to find too! 

One day when I was up under the engine with the cowl off with a flashlight

and spanner wrench tightening the lower exhaust collars trying to chase down

the leak. A drip from the overflow tube on the left side of the fuel pump

blessed me by hitting me in the face! 

So saying all that, don't assume that it is from only the carb. You may well

have some diaphragms wearing out in the carburetor but after a couple of

discussions with Rob Kent in England, Carl Hayes, and Steve Culp with Dennis

and I both scratching our heads, all confirmed that it was extremely rare to

have a problem with the carburetor (Dennis too). So look at the overflow

vent on the left side of the fuel pump. If you have you have any fluid

dripping down from the side, you have a pump diaphragm seal going bad. That

will be followed by the oil seal going bad with the symptom of oil dripping

from the 

Overflow vent.

Oh, I also saw fuel residue on the drip pan after she sat for a for a couple

of days in the hanger. I also saw it dripping out of the back of the air

breather box where the ram horns would attach if I still had mine on the

plane. I saw that after shutdown, with it sitting for a little while, and I

vaguely remember seeing a few drops after I primed and pulled blades.

Maybe this helps some too.

Doc

--

dstroud(at)storm.ca
Guest

Posted: Sat Aug 04, 2007 7:29 pm Post subject: Yak 50 priming drip

Amigos...this recent talk about primers got me looking for one and I found a new

one on ebay for 100 bucks. They state it's for all Yaks etc and being a two way item,

it primes the cyls and / or pressures the carb. I'm installing a Huosai and know 

bugger all about the primer needs. Is this type of primer something I should grab 

right now or would some other arrangement be more suitable ...ie ..electric etc. ?



Or..if some lister can sell me one direct, that would be my preferred route. 

Thanks...



David Stroud   Ottawa, Canada

C-FDWS  Christavia 

Fairchild 51 under construction

and on the gear...



---

viperdoc(at)mindspring.co
Guest

Posted: Sat Aug 04, 2007 8:11 pm Post subject: Yak 50 priming drip

Dave,

I have a YAK which has an M-14P. The primers for both the M-14 and the

Housai are the  same. I would personally trust on from Doug Sapp, Carl

Hayes, Steve Culp, Rob Kent or George Coy long before I would trust the one

one EBAY for the highest bidder. Since it is my rosey pink that is dependent

on that part, I prefer getting it from someone has supplied me with reliable

parts in the past.

To answer the rest of your question, yes you need that type primer. You

could come up with an electric pump to do the job also at a higher cost. I

prefer the existing one that I have which the factory stock one.

Doc



--

john(at)johnalber.com
Guest

Posted: Sun Aug 05, 2007 12:22 am Post subject: Yak 50 priming drip

Guys,



Thanks for all the input. My usual procedure is to prime and

pull through on first start-up. We noticed the drip while doing

an annual with the cowling off. I hadn't noticed it before. We

weren't starting up, just looking for things

like...well...drips. The drip was on priming, not pressurizing.



Tim,



I've had my 50 for a year and a half. I bought it from Michael

Lloyd. Some years back, I also had a 52.



John



John Alber

john(at)johnalber.com

314-259-2144

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Sun Aug 05, 2007 2:55 am Post subject: Re: Yak 50 priming drip

John,



You got a nice bird from Freezer. (Lloyd). We hated to see him part with  it but glad it stayed here in the states. (he has a beautiful Glasair III now) We recently had a Yak-50 go overseas! 



Welcome to the -50 community!

rvfltd(at)televar.com
Guest

Posted: Sun Aug 05, 2007 6:16 am Post subject: Yak 50 priming drip

David,

I have brand new CJ6 / Huosai primers in stock for $100.00 each.  I also 

carry all the elec/pneumatic start parts if you need them. 



Always Yakin,

Doug



david stroud wrote:



[quote]



Amigos...this recent talk about primers got me looking for one and I found a new

one on ebay for 100 bucks. They state it's for all Yaks etc and being a two way item,

it primes the cyls and / or pressures the carb. I'm installing a Huosai and know 

bugger all about the primer needs. Is this type of primer something I should grab 

right now or would some other arrangement be more suitable ...ie ..electric etc. ?



Or..if some lister can sell me one direct, that would be my preferred route. 

Thanks...



David Stroud   Ottawa, Canada

C-FDWS  Christavia 

Fairchild 51 under construction

and on the gear...



---

mark.bitterlich(at)navy.m
Guest

Posted: Sun Aug 05, 2007 9:44 am Post subject: Yak 50 priming drip

I've flown three 50's and have never seen that happen, including the 700

hours or so I have in mine.  I would take a hard look and make sure it

is not a case of it leaking somewhere else and then running down to the

lowest point and then dripping.  Start at the priming hose itself,

especially at the fittings at the end of the hose itself.  Then where it

connects to the manifold tube area.  If you do not see it there, my

guess is that you should look at the lowest intake manifold tube and

look for a loose oil drain cap. I have an oil drain kit coming from the

low cylinders that puts a fitting and #4 line into each of those drain

caps.  When I prime, the fuel runs to that lowest area and then OUT of

the drain itself.  If I leave this drain closed, ZERO fuel comes out of

anywhere.  Thus, I suspect you've got a leak in one of those caps, (or

lines if you have this mod, especially if you are using solid aluminum

tubing which was what was used  by some people that installed this mod,

which is NO GOOD AT ALL!).  



I'd advise you to not ignore this leak.  It is not a good thing, nor is

it normal... No offense to Dennis meant. 



Mark Bitterlich

--

mark.bitterlich(at)navy.m
Guest

Posted: Sun Aug 05, 2007 9:47 am Post subject: Yak 50 priming drip

Sorry to disagree gents, BUT!   I have primed the snot out of my 50 and

have NEVER had fuel leak out of the bottom of the engine.  Out of the

exhaust ... Sure... Especially when priming and then pulling the prop

through.  I've had it come out of the intake drain lines especially with

the drain kit installed and the valve open.  



I have even had it come out of a CRACK in one of the INTAKE TUBES (hint

hint).  



I disagree that it is normal under any condition.  Take a look at how

this system works.  It would have to get down, back out the blower, and

then down to the carb to come out.  



Mark Bitterlich

 



--

brian-1927(at)lloyd.com
Guest

Posted: Sun Aug 05, 2007 10:06 am Post subject: Yak 50 priming drip

On Aug 4, 2007, at 11:26 PM, david stroud wrote:



 	  Quote: 	
		   



 Amigos...this recent talk about primers got me looking for one and  

 I found a new

 one on ebay for 100 bucks. They state it's for all Yaks etc and  

 being a two way item,

 it primes the cyls and / or pressures the carb. I'm installing a  

 Huosai and know

 bugger all about the primer needs. Is this type of primer something  

 I should grab

 right now or would some other arrangement be more  

 suitable ...ie ..electric etc. ?



 Or..if some lister can sell me one direct, that would be my  

 preferred route.

 Thanks...


	


Well, I can tell you what I am doing for The Project. I have replaced  

the wobble pump with an electric fuel pump. I plan to use a solenoid  

valve from the output of the electric fuel pump and before the  

mechanical fuel pump to valve fuel into the primer line on the  

engine. It will be actuated with a spring-return switch. Turn on the  

aux pump and hit the primer switch to prime the engine. No more  

primer pumps and no needing three arms to work the wobble pump to fly  

the airplane should the mechanical pump fail.



Just another idea for you.



--

Brian Lloyd                         3191 Western Drive

brian HYPHEN 1927 AT lloyd DOT com    Cameron Park, CA 95682

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry



PGP key ID:          12095C52A32A1B6C

PGP key fingerprint: 3B1D BA11 4913 3254 B6E0  CC09 1209 5C52 A32A 1B6C

dsavarese(at)elmore.rr.co
Guest

Posted: Sun Aug 05, 2007 2:57 pm Post subject: Yak 50 priming drip

It could very well be a leaking diaphragm in the carburetor.

Dennis



---

jan.mevis(at)informavia.b
Guest

Posted: Sun Aug 05, 2007 10:33 pm Post subject: Yak 50 priming drip

Of course you're right, Mark. 



Nevertheless, I started a fire once, after priming too much. I still don't

know how or why, since the engine was not hot. I did not have any (known)

leaks. Since then, I always try to have someone in the nearby.



Jan 



--

mark.bitterlich(at)navy.m
Guest

Posted: Mon Aug 06, 2007 5:24 am Post subject: Yak 50 priming drip

I'd like to hear the details on the fire Jan.  I would suspect it

happened once the engine starting cranking.  It would be very easy under

such circumstances for the gas to light off in the cylinder and then

come out of the exhaust on fire and create quite a mess in the process.

Mark

 



--

jan.mevis(at)informavia.b
Guest

Posted: Mon Aug 06, 2007 5:51 am Post subject: Yak 50 priming drip

Yes, it was something like that. I remember the engine "coughing" one or two

times and then nothing. At that time, I had a bad, lazy starting-valve. The

shower-of-sparks at the contrary worked very well. So it is probable that

one cylinder fired, and with spilled fuel in the exhaust, it probably gave a

flame large enough to ignite oily stuff on the bottom of the cowling.



Since then, I not only try to have someone nearby when starting, but I also

keep the engine compartment clean.



Jan



--

mark.bitterlich(at)navy.m
Guest

Posted: Mon Aug 06, 2007 1:26 pm Post subject: Yak 50 priming drip

Roger that! 



Mark

 



--

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