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Ideas on why glow plug failed from one day to the next - 7/7/2008 4:48:46 AM   
jollycub


 

Posts: 146
Joined: 7/29/2005
From: Omaha, NE, USA
Status: offline 		I have an OS61 engine on an Astro Hog. Friday, the 4th of July, I flew it for 3 flights with no problems whatsoever. It started on the first hand flip each time I started it. The fuel which is SIG 15% came out of the exhaust as pink as when it was in the bottle which means I wasn't flying it lean. Today, I tried to hand start it, but had no luck. I got my electric starter and it still wouldn't start. Thinking the battery was low on my glow stick, I borrowed one from a buddy at the field and still no luck. As the last resort, I changed the glow plug and it started by hand flipping it the first time. When I took the old glow plug out of the head, I turned the engine upside down and some fuel came out, but this was not from priming the carburetor. I do not open the carb wide open and hold my thumb over it. I have had too many fuel locks by doing this so I just let the engine turn over until the fuel goes into the carb. Usually this doesn't take long since I fill the tank thru the fuel tube that goes on the carb and it is usually full when I put the tube back on the carb. Soooo, any ideas why I burned up the glow plug. We did try the glow driver on the old plug and it didn't glow.

Thanks for your advice.


       Post #: 1

RE: Ideas on why glow plug failed from one day to the ... - 7/7/2008 5:12:25 AM   
Deathbunny_SG


 

Posts: 175
Joined: 3/4/2008
From: , NJ, USA
Status: offline 		If your burning plugs up that fast it might be to lean.

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RE: Ideas on why glow plug failed from one day to the next - 7/7/2008 5:14:10 AM   
Campgems


 

Posts: 1805
Joined: 2/18/2006
From: Arroyo Grande, CA, USA
Status: offline 		Glow plugs are like light bulbs. I'll bet if you had been setting on the top of the piston, there would have been a flash when you hooked up the glow igniter. They work well one minute, but the next time you turn them on, nothing.

It could have been old age, it could have been infant mortality. I wouldn't go nuts over it, put another in and go fly. When you start popping them like popcorn, then start wondering why and then find out why.

Don


(in reply to jollycub)
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RE: Ideas on why glow plug failed from one day to the next - 7/7/2008 5:16:36 AM   
Gizmo-RCU


 

Posts: 967
Joined: 9/17/2002
From: Athol, ID, USA
Status: offline 		I have had similar problems, there is no explanation sometimes. I would worry it it becomes consistant. Over charged glow drivers, metal fragments from the engine and old age of the plug seem to be the primary problem. The metal fragments can happen in new engines during break-in, they attach to the hot glow coil and cause plug failure. I use old questionable plugs for bench running/break-in and then put new ones in for flying.

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RE: Ideas on why glow plug failed from one day to the ... - 7/7/2008 10:24:49 AM   
flyX


 

Posts: 586
Joined: 7/24/2007
From: el centro, CA, USA
Status: offline 		Plugs will also fail if it's too rich...due to oil residue build up on the coil.
Mabe lean the LSN a little bit.

Generally the coil will get broken if it's too lean

(in reply to Gizmo-RCU)
       Post #: 5

RE: Ideas on why glow plug failed from one day to the ... - 7/7/2008 11:17:21 AM   
jetmech05


 

Posts: 1565
Joined: 7/12/2005
From: Jacksonville, FL, USA
Status: offline 		Did the coil of the old glue plug looked pushed in? If so then something probably did go through the engine..could have been a small piece of carbon from the muffler or something from the runway...Like Gizmo said I wouldn't worry about it unless it becomes consistant

(in reply to flyX)
       Post #: 6

RE: Ideas on why glow plug failed from one day to the ... - 7/7/2008 2:31:29 PM   
Fastsky



Posts: 2842
Joined: 12/10/2001
From: Calgary, AB, CANADA
Status: offline 		I turn the power down, take the glow plug out of the engine and hook it up to the driver. Then slowly crank it up until you get a nice glow, not too bright, and then use that setting for the glow plug. I found huge differences in the settings to get a good glue even with the same brand and model of plug. IF the setting is too high, then the plug will burn out very quickly. I found this out out after going through several plugs the hard way. You can't go by the "green" part of the scale on the meter. ITs way too high a setting in most cases!! Hope this helps, Fast!

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RE: Ideas on why glow plug failed from one day to the ... - 7/7/2008 3:01:47 PM   
flyinrog



Posts: 5691
Joined: 9/3/2002
From: Burlington, NC, USA
Status: offline 		Dont worry about 1 or 2 glow plugs...if it gets to be too many than more than likely it is your glow driver popping them,,a couple weeks ago we had a funfly where a guy brought out a 20 year old pattern plane, he flew it once, but the second time he went to crank it,, plug was dead,,it was the original plug,musta been 10 guys offer to give this guy a plug, most modelers are good guys, I bought a flight box with a power panel and popped 3 plugs before I figured out the glow driver was burned out and running the 12 volts straight through it!!....Rog

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RE: Ideas on why glow plug failed from one day to the ... - 7/7/2008 5:57:33 PM   
RCKen



Posts: 14457
Joined: 7/10/2002
From: Lawton, OK, USA
Status: offline 		As was mentioned above, don't worry if it was just one plug. Like light bulbs, they just die occasionally. Put a new one in and fly. The time to start considering if something is wrong is if more plugs start going out. If your engine starts going through glow plugs then it's time to try and figure out why. But for just one plug I wouldn't lose a whole lot of sleep over it.

Ken

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(in reply to flyinrog)
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RE: Ideas on why glow plug failed from one day to the ... - 7/8/2008 3:37:26 PM   
chashint


 

Posts: 874
Joined: 1/1/2002
From: Rowlett, TX, USA
Status: offline 		jollycub,
You didn't tell to much about the engine and the glow plug other than it worked fine then didn't.
Is this a one time occurance or is this something that is repeating itself ?
If a glow plug is going to fail I think this is the best way for it to go, works great no issues at all during the flight and taxi back to the pit and then nada zilch caput.
Sometimes they die a slow painful frustrating death that causes one to relentlessly adjust both needle valves, just to be frustrated and continue to have problems, stubbornly clinging to the belief that the plug only has a few flights on it and cannot possibly be bad.
I have also found that new engines tend to eat one or two glow plugs rather quickly and then the glow plugs last a long time between failures.

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regards,
Charlie

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RE: Ideas on why glow plug failed from one day to the ... - 7/9/2008 3:44:21 AM   
Charlie P.



Posts: 2259
Joined: 2/25/2003
From: High Above Upstate, NY, USA
Status: offline 		Sometimes they last months and sometimes they only last a few flights. You stand inside a running engine and see what kind of environment that is for a flimsey little filament to endure.

Things like vibration (is your prop balanced), bouncing in a car trunk, overheating . . . I just had one last season that was dead right out of the wrapper. Used to be more common than it is now (or maybe because I don't use Fox plugs anymore).

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Charlie P.
"Gravity is weak but it is persistant" AMA 747089/IMAA 30723

Oh Lord, your earth is so hard and my planes are so frail.

(in reply to chashint)
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RE: Ideas on why glow plug failed from one day to the ... - 7/10/2008 3:54:10 PM   
Flypaper 2



Posts: 4275
Joined: 3/29/2002
From: Kingston, ON, CANADA
Status: offline 		Two other points. To hot of a plug for the engine and fuel and leaving the nystarter on to long. With the nystarter on after it's warmed up, the fuel is lighting the plug as well as the batt.

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Gord
Dreamed I was a muffler. Woke up exhausted.

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RE: Ideas on why glow plug failed from one day to the ... - 7/11/2008 7:08:41 AM   
victorzamora


 

Posts: 591
Joined: 10/16/2006
From: Mt. Airy, NC, USA
Status: offline 		I've had plugs that last 3 or 4 flights, and none of them blew because my engine was running lean. I always tune my needles on the rich side, so I know it wasn't that.
The plug I currently have on my 46AX is the same plug that I broke it in with, and I've put like 3 gallons through it since break-in.

Plugs are hit-and-miss when it comes to durability. Everyone else is also right about the fact that plugs don't slowly degrade, they go from 100% to 0% in a split second.

(in reply to Flypaper 2)
       Post #: 13

RE: Ideas on why glow plug failed from one day to the next - 7/14/2008 6:45:52 PM   
jollycub


 

Posts: 146
Joined: 7/29/2005
From: Omaha, NE, USA
Status: offline 		Thanks for your response. I have to glue the tail wheel back on to se if the glow plug is still good.

(in reply to jollycub)
       Post #: 14

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