REFLECTOR: Franklin Will not turnover when hot

[steve beilby]

Hi Mike,

My Franklin used to be very hard to turn over by hand after landing. 

As someone else has already mentioned, I think it has to do with a hot engine 
(normal operating temps in cruise) cooling quickly in the descent/approach.  
This causes the cylinder to contract (shrink a little) onto a hot piston 
significantly increasing friction.

How many hours on your Franklin?

This is only my theory; but when I planned my descents further out and kept some 
power on, to keep the cylinders warm - the engine was easier to turn over (by 
hand) after landing.

My Franklin had great cylinder cooling with the factory plenum (Oil temps were a 
real pain though). This could exacerbate the issue.

A simple test; turn the engine over by hand (mags off of course) before and then 
again after flight - any noticeable difference?
Just wondering if you are going off into the weeds a bit looking at 
electrics/starter????

Steve




________________________________
From: Michael Watson <mikewatsspg at gmail.com>
To: sbjknox <sbjknox at earthlink.net>; Velocity Aircraft Owners and Builders list 
<reflector at tvbf.org>
Sent: Thu, 19 May, 2011 11:01:21 PM
Subject: Re: REFLECTOR: Franklin Will not turnover when hot

Sid,

Timing is checked at every annual, It's always right on, I actually have it set 
one degree retarded from recommended setting.  The engine does NOT kick 
back it just stops. releasing the starter releases the compression. I am an 
electronic 

engineer and am familiar with and tried most of the test procedures you 
mentioned. 

11.2 volts at the starter while cranking, .8volts drop across main contractor 
and .65volts
across starter contractor. After three tries, none of the wires get hot.  

Jeff,

I'd love to, but it just wont fit.





On Wed, May 18, 2011 at 11:41 PM, sbjknox <sbjknox at earthlink.net> wrote:

I have been thinking about my last post and the possible early timing issue
>and realize that for a test you don't need to mess with the timing, simply
>try and crank it with the mags off.
>
>But beyond that, I suggest you make some voltage measurements...
>1) Connect a voltmeter directly between the 'hot' starter terminal and the
>case ground.  Crank for a couple seconds (mags off) and record voltage.
>2) Repeat with the voltmeter  directly across the battery posts, not on the
>cable clamps (or whatever you use to connect to the posts).
>3) *Important* don't remain in the "locked rotor" crank mode for more than
>two or three seconds.  There will likely be hundreds of Amps flowing and
>this equates to *many* Kilowatts of heat being generated!
>4) After taking the voltage readings, feel with your hand, each and every
>connector, terminal, the starter and master solenoids for something hot.
>Warm can be normal but not hot.  Don't forget the return (GND) path from the
>battery to the engine.  In that short of time, the mass of the battery and
>starter is such that you probably won't notice any heat build-up in them but
>be assured that if you hold the locked-rotor current for an extended period
>of time, you will likely destroy the starter and/or battery and solenoid(s).
>(altho, the long run of  #2 wire might save it).
>
>A six-dollar Harbor Freight digital voltmeter and some basic
>trouble-shooting  will serve you better than throwing several hundred
>dollars worth of starters and batterys on speculation at the problem. 
>
>
>Sid Knox
>Oklahoma
>
>Velocity  173 RG  N199RS
>Starduster  N666SK
>KR2         N24TC
>W7QJQ
>
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-- 
Mike W.
1997 Velocity Elite RG
Franklin /IVO Electric CS
Dual GRT EFIS HX Synthetic Vision
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