REFLECTOR: "Stuck" Franklin

Tue Feb 18 07:08:19 CST 2014

I still believe it is likely that a valve is stuck open and the piston is coming in contact when it gets to that point of rotation. A boroscope could confirm this through a spark plug hole.
Grover McNair

Sent from my iPad

> On Feb 17, 2014, at 4:30 PM, "Grover McNair" <grover at mcnairperformance.com> wrote:
> 
> Call Robert Still at Southern Aero (336) 476-9094. He specializes in Franklin engines and has presented at Oshkosh as well.
>  
> Grover McNair
>  
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Hiroo Umeno
> Sent: Monday, February 17, 2014 3:52 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: "Stuck" Franklin
>  
> I spent some time poking around in there this weekend.  Still nothing conclusive but I did find out the following.
>  
> 1.       Pulled valve covers off #5 and #6 cyl (most accessible) and found that the parts are well lubricated, saturated in oil and found no sign of corrosion.
> 2.       Pulled gear cover and confirmed that starter gears are disengaged and accessory gear spun freely.
> 3.       Took off crank case cover on top and inspected the internals with bore scope.  No corrosions evident internally.  Cam shaft rotation confirmed.
> 4.       Prop rotation observed to be free between 0 degrees TDC to 180 degrees BDC.
>  
> This last one got me rather curious.  It seems very odd that something will block the rotation EXACTLY at Top Dead Center.  This was confirmed both through prop hub marking and the cast mark on the piston cranks itself.
>  
> So, if I can figure out what is happening when the crank shaft is at TDC and BDC, I have a shot at identifying the specific cylinder or the valve I need to tear into.  Anyone familiar with Frankly who has insight into this?  I called Susan at Franklin Engines and I am also waiting for a call back from their mechanic as well.
>  
> Hiroo
>  
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of James Traynor
> Sent: Tuesday, February 04, 2014 6:32 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: "Stuck" Franklin
>  
> When you find the stuck valve use a very good antisense lubricant and work the valve if you can very slowly for days until free. Work the engine around a lot to free up other valves. You may wont to lubricate the other valves at this time. 
> I had a 1949 flat head Pontiac that had not run for 12 years when I got it. Dad pulled the plugs and added a antisense lubricant and sprayed the valves through the side inspection plate. After a week we turn over by hand and freed up the engine added good fuel primed and I could not be leave that it started first try. 
> It takes a lot to bend a valve and you will see marks on the top of the piston if you have a scope. Look to see if some one tried to turn over with the starter and had valve to piston hit. If a hard hit happened the connecting rod may be bent.
> Good luck and go slow it will save you money in the end
>  
> James
> From: humeno at microsoft.com
> To: reflector at tvbf.org
> Date: Tue, 4 Feb 2014 21:36:40 +0000
> Subject: Re: REFLECTOR: "Stuck" Franklin
> 
> Thanks.  I didn’t pull the prop very hard knowing that stuck valves were a distinct possibility.  We will follow your suggestion to see if this is the case.
>  
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Laurence Coen
> Sent: Tuesday, February 04, 2014 9:23 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: "Stuck" Franklin
>  
> Hiroo,
>  
> I still suspect a stuck valve.  If you turn the engine to the stop point and check which pistons are in the up position and remove the valve covers on those cylinders you can check the rockers to see if the valves are fully retracted.  The only thing in the engine that happens at 180 deg. rotation is the crank and what is attached to it (pistons).  Since you have pulled the plugs, it can't be hydraulic lock.
>  
> Larry Coen
> N136LC
> Franklin/IVO
>  
> From: Hiroo Umeno
> Sent: Monday, February 03, 2014 11:34 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: REFLECTOR: "Stuck" Franklin
>  
> Franklin Experts,
>  
> We are just starting to re-activate an aircraft that has sat for 7 years in a hangar storage.  When we flew it last, the aircraft flew well and the engine performed as expected.  This an installation on a Velocity and it has the oil cooler bypass fix that was needed to operate at proper oil temperature.
>  
> The engine is a PZL built 6A-350 that has approximately 27 hours since major overhaul / rebuild.  The aircraft has engine driven fuel pump and dual slick magneto ignition (no electronic ignition). 
>  
> When we pulled the plugs off and attempted to hand turn the prop, we discovered that the prop will not complete the full turn.  Rather, there is a definite stop point at 180 degree rotation in either direction.  Inspection of the cylinders reveal no piston contact with valves and no obvious blockage.  No new parts have been installed since it was last operated. 
>  
> I am wondering if there is a “likely suspect” that we should look at first.
>  
> Hiroo
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