Nf-ID: #R:peak.psl.nmsu.edu:26010213:trsvax:1195667304:000:5053
Nf-From: trsvax.tandy.com!earl    Aug 26 16:58:00 1992



/* ---------- "crummy glow plugs?" ---------- */
OK, I know I'm not R/C, but I'm having a problem some of you might know
something about. I've been using basically stock OS-40FPSes (C/L version,
with venturi, smaller muffler, and 2 head gaskets) in my stunt ships. They
work surprisingly well, and I've had very good luck with them. Instead of
buying the expensive OS glow plugs however, I have been using the econo
Tower R/C longs, with idle bar. They last and last and I end up putting in
a new plug every six months or so.
OK, fine. Suddenly I started experiencing a flame out, which turned out to
be cured by replacing the plug. When it failed, the plug looked perfect,
but the engine would just die, like it was shut off, a short period after
the battery was removed. I tried different fuel, fuel filters, with the
same exact symptoms. 
The problem was that this fix apparently only lasted about a dozen flights
(our stunt patterns take under 8 minutes). And it took another plug to fix
it again. I also tried some K & B plugs, which also ran well, but did the
same thing after FEWER flights.
Windy Urtnowski crashed his concourse winning stunter at the Nats this
year due to a similar problem, and he was using a Fox Miracle plug.
According to him, after the Nats, Big Jim Greenway started testing these
plugs for the problem and found only 3 good ones in a test sample of 48!
Windy seems to think it is a bad "batch" of plugs. And I'm assuming that
Tower's econo plugs may be from the lowest bidder and therefore varying in
quality. Maybe the PT plating is bad?
I am going to do some experimenting myself on other engines and plugs. I
thought this particular engine might be having a problem, perhaps somehow
contaminating its plug elements or something. I recently had to replace
its so-called ABC cylinder/piston assembly because it was showing brass.
Something apparently went through the engine..
Anyway, I opted for steel/iron for the replacement liner/piston and it
looks just perfect (I gave it a careful break in, about 1/2 gallon of
fuel). And, that was many months ago, with the engine running perfectly
all that time and only recently exhibiting this problem.
Any ideas?
Thanks in advance for your comments.
L.
"Yeh, Buddy..            | larry@psl.nmsu.edu (Larry Cunningham)|  _~~_
 I've got your COMPUTER! | % Physical Science Laboratory        | (O)(-)
 Right HERE!!"           | New Mexico State University          |  /..\ 
 (computer THIS!)        | Las Cruces, New Mexico, USA 88003    |   <> 
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   If you have several FOX plugs that exhibit this problem, send them to FOX
   with your story and they'll analyze the plugs and respond. 

   The key element in the glow plug element is PLATINUM. AS inflation and costs
   rise, everyone tries to cut down to the smallest amount of platinum they can
   get away with and still have a plug that works. From time to time the
   wire manufacturer screws up the formula, and runs off "N" number of feet of
   substandard glow plug element wire. Then whoever gets the wire makes "N"
   number of marginal glow plugs. The lowest cost plugs naturally have the
   lowest cost quality control.

   I remember a number of years ago having a problem like this, and it wound
   up being a bad batch of fuel (of all things). In the last year or so, with 
   the "sic" nitro shortages, it's possible that some batches of fuels are
   not up to snuff. Water in the fuel will also cause similar problems.

   But then many mysteries still exist. Last year I put a new FOX 40 on my
   Ugly Stick, and it promptly ate three FOX plugs, in three tanks of fuel. Then
   it stopped eating plugs and ran for a year off of one FOX Miracle plug! I
   never did come to any conclusions on what happened during the first few
   engine runs.

   Also, if some metal particles get loose inside the engine, these small
   bits of metal dust interact with the glow plug element during combustion
   and contaminate it. This causes the glow plug element to go bad very
   quickly too. This would happen, if your using a bushing engine versus a
   ball bearing engine, and your using a electric starter to fire up the
   engine. What happens is that as the engine gets older, the starter pushes
   on the crankshaft causing it to move back and rub the crankpin against the
   backplate. The little bit of aluminum that gets scraped off can cause the
   glow plugs to fail prematurely.



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<This information is provided by an individual and is not nor should be
 construed  as  being  provided  by  Radio  Shack or Tandy Corp.  Radio
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 in  any way. > 
						
						Earl W. Bollinger
						@ <trsvax!earl>


"You were in the Clone Wars!", said Luke excitedly.
"Yes", replied Obi Wan, "I was a DOS programmer. But that was before the dark
 times, before OS2."