i have a magnum .52 2 stroke running on 10% and thunderbolt r/c long idle bar plugs. i'm using the 12.25x3.75 prop (which is probably only about an 11 now b/c i've dinked it a couple of times on landings).

lately, my plugs keep on burning out. i'd have about 2 flights on them before they need to be replaced, sometimes, just one flight!

i've been through about 5 plugs already in the past 2 weeks! i made sure i wasnt running too lean and have opened up the needle valve even more and am almost certain i'm running rich now but the problem continues.

does anyone have any ideas or suggestions? maybe i just got unlucky with a bad batch of plugs from thunderbolt?

thanx,
brian

Understandably a frustrating problem boosted, let me give you a couple of suggestions, I am by no means an expert, but I hope I can help.

First of all, make sure the glow plugs you are using will work well with your engine in the first place. Have you tried a different plug to see if you ran into the same results?

Secondly, an engine running to rich can cause just as many glow plug problems as an engine running to lean. In my opinion(I have been running r/c car engines for the last 3 years, so forgive me if there are subtle differences with plane 2 strokes), running to rich is worse then running to lean on a glow plug. I am not saying to run your engine too lean, just that generally I experienced more engine related problems then glow plug problems when running too lean. Try to tune the engine with a tach if you can to make sure you are tuning the engine optimally, and use a temp gun if you can to measure the temp at the plug. If it is getting too hot at the plug, this can also cause plug failure.

Last, I would make sure your engine is in top notch shape to begin with. Does it still have good compression? Are there any leaks? Is the engine running well before the glow plug goes bad? Is your fuel in good condition? (Remember the combustable portion of glow model fuels can evaporate, make the fuel a non combustable oil, which is why so many people have problems with engines after storing them over the winter).

Try to take a step by step approach to the problem, and make sure you contact your engine manufacturer if the problem persists. Hope this helps! But most importantly, a $15-$25 tach can help you get the most out of your engine, and help ensure that you are always running at the optimum mixture.

Trixer has alot of good suggestions. When I start blowing plugs like that it's usually right about the same time my compession drops and I need a new motor... Running 'em at 17K RPM piped on 30% heli takes it's toll. But thats another story...

anyone got a 2S 60 laying around?

Hi

I have never known rich running to kill a plug - lean obviously does.

It could be that your bearings ( or other metal parts) are dissintegrating and the shards are breaking the element of the plug - look for pit marks on the plug base etc.
I have found that if the element breaks in flight it does not nessaraly kill the motor but when you try to start it again it is dead.

Also check for air leaks that could cuase your motor to go lean in flight.

well, i have the exactly same problem with my os 160fx, it keeps burning plugs every 2-3 flights (days of flying) and i only use os #8 plugs or os A3 when i run out of #8s..

this is just a thought, i have no idea if its correct, but it might be corrosion??? after 1 week of storage.. because i fly 3d at ground level, i need my engines to be 100% eficient and safely, and i never had a single problem with my engine when ive benn flying or i just replaced the plug... but when i go back home and come next weekend, my engine is so bad that it wont even start ot hold idle and the problem goes away with a new plug... maybe that i fly in peru (very humid weather) and i fly close to the ocean (salt contributes in corosion) my plugs get corroded when i go back home..

besides that my engine is one og the most trasted engines ive ever had, never had a dead stick ecept on the 1st flight of the day, and when i have a dead stick, i put a new plug and it becomes the most trusty engine ever...

Here is another thought for you. You said that you dinked your prop a few times and it is now smaller in diameter right? Is the prop really rebalanced? The vibrations from an unbalanced prop could easily be causing your troubles... For what its worth

I'm running a 48 on a pipe at 13.5k turning a 10x7, and it's blown 3 enya #3 in the last 5 flights, and im scratchin my head. It ran fine before, then I didnt fly for 10 months(never normally a problem) but still put fuel through to keep it alive. then after i land, it doesnt start.

Will going up a prop or two and bringing the revs down help? Or do i just forget it and fly something else?
Thanks

My experience has been the same as trixers... In R/c Cars Planes, and 2 stroke dirtbikes. A rich engine will kill your engine faster than a lean one. My ST hasn't killed a plug in 8 gallons.. I haven't changed it either.. The element still looks great and I'm not running it lean, but get some smoke out of it.. I don't use a tach or anything, just tune for good transition and good top end.

I found the following from a site, it might help you.
_

Glow Plugs...It's gettin' hot in herre!

Glow plug...What is it? Let's check out Webster's Dictionary:

Main Entry: glow plug
Function: noun
Date: circa 1941
: a heating element in a diesel-engine cylinder to preheat the air and facilitate starting; also : a similar element for ignition in other internal combustion engines

Basically, the glow plug is used to provide ignition for the fuel/air mixture in an engine...in a similar manner to a spark plug in a gasoline engine.

So how does it work? To start the motor we must first heat up the element (the small coil of wire inside the plug) by connecting it to a battery. Most plugs use 1.5 volts to pre-heat the coil. Once the motor is running the battery can be disconnected and the plug will continue to glow with an orange heat to provide ignition and keep the engine running.

How does it do this without a battery? It all hinges on the fuel we use (or part of the fuel) and what the element is made from. The working part of the fuel is methanol, a type of alcohol (but not the drinking kind) which is quite poisonous. The element is made from several metals alloyed together to make it strong enough to handle the heat and vibration induced from engine operation. The specific metal in this alloy that we are interested in is platinum. When platinum comes in contact with alcohol there is a catalytic reaction between the two which heats the platinum while causing the alcohol to ignite.

But if the element is glowing the entire time the motor is running, how does the fuel know when to start burning (in other words, what determines the ignition point)?

Well this goes back to the catalytic reaction again. This reaction depends on two things, one is the temperature of the element (the hotter it is the easier it will react) and the pressure of the fuel/air mixture inside the cylinder (the higher the pressure the easier it will react).

So is this where "hot" and "cold" plugs come into play? Exactly. Glow plug temperature is controlled by using different heat range plugs. Just like automobile spark plugs, glow plugs come in different heat ranges from hot to cold with maybe half a dozen steps in between. If in doubt, use the plug specified by the engine manufacturer. Using a hotter plug than normal will advance the ignition point and a colder plug will retard the ignition.

You talked about pressure of the fuel/air mixture...what the heck was that all about? The pressure of the air/fuel mixture is determined by the compression ratio of the engine and normally is fixed by the manufacturer. You can vary this compression ratio slightly by adding or removing shims under the cylinder head. This is not something to play with unless you know what you are doing.

Ok, so can I run any glow plug with any fuel? Not really. There are a couple of plugs that are said to be for general use (O.S. #8 and #0), but the more nitro you run, the more you advance the ignition point. What's that mean? In an ideal situation the glow plug will ignite the air fuel mixture when the piston is at top dead center (TDC), which will force the piston down and back up for another compression stroke. When you run a higher nitro percentage (and don't go to a colder plug) you'll advance your ignition point (the point at which the glow plug ignites the air/fuel mixture), which will result is less than optimum performance since the piston is still on it's compression stroke when the air/fuel is ignited and not at TDC.

The general rule regarding glow plugs and nitro fuel is:

The higher the nitro percentage, the colder the plug should be.

Conversely:

The lower the nitro percentage, the hotter the plug should be.

OK, cool enough. Where can I find info on these plugs?

Glad you asked. Check out this list of info on McCoy's Glow plugs, with heat ranges and applications.

MC-4C: 4-cycle engines

MC-55: The MC-55 is considered a hot plug and is designed to run on fuel with a low nitro content. Applications for this plug would be planes, tether cars, etc.

MC-59: Like the MC-55, the MC-59 is considered a hot plug. The difference between the 55 and 59 is that the MC-59 is designed to run on fuel with a higher nitro content (low to medium nitro content) than the MC-55. Applications: Boats, planes, heilcopters, and cars.

MC-8: The MC-8 is a medium to cold plug, deisgned to run on fuels with a medium to high nitro content. Applications: Boats, cars, and planes.

MC-9: The McCoy MC-9 is considered a cold plug and is designed to run on fuels with a medium to high nitro content. Applications: Cars, boats, ducted fan and Giant Scale planes.

MC-14: The MC-14 is a hot plug, designed for helicopters and 4-stroke engines.

From reading just these bits of info on McCoy's plugs, you can easily see that general rule...if you're running fuel with a high nitro percentage, you should be using a glow plug that's considered to be a "cold" plug. Conversely, if you're running a low nitro content in your fuel, you should be using a "hot" plug.

The following are lists of OS and Novarossi plugs. These plugs follow the same nitro/heat range rules as demonstrated with the McCoy's plugs.

OS PLUGS

OSMG6300- #0 Economy standard plug similar to the O.S. #8.
OSMG6304- #1 Hot plug for low nitro (0-5%).
OSMG6308- #3 Medium plug for medium nitro (5-25%).
OSMG6312- #5 Cold plug for high nitro (25% +).
OSMG6316- #7 2 stroke engines requiring an idle bar.
OSMG2691- #8 "The" standard. For use in all 2 strokes, any nitro.
OSMG6320- #9 For general use in 2 stroke engines.
OSMG2692- #F For O.S and other four strokes.


Novarossi Plugs

10001 R1 Extra hot from .8 TO 2CC
10002 R2 Hot from2 TO 3.5CC
10003 R3 Medium from 3.5 TO 6CC
10004 R4 Cold from 6 TO 10CC
10005 R5 Extra cold for nitro fuel and RC
10006 R6 Cold for nitro from 10 - 13CC
10007 R7 Cold for nitro from 13 - 15CC
10008 R8 Super Cold for nitro from 15-30CC
10010 RC Hot for RC from 2.5 TO 6CC
10020 RC Cold for RC from 6 TO 15CC
10011 G1 Hot for R15 Speed
10022 G2 Medium for R15 Speed
10033 G3 Cold for nitro fuel from 18%-30% for R15 Speed.
10044 G4 Extra cold for nitro fuel from 30%-15% for R15 Speed
10055 G5 Extra cold for nitro fuel from 50%-70% for R15 Speed.


Actually, I hope that this helps you...there's more to glow plugs than telling the guy at the hobby shop "I need a plug for a .21". Don't just buy a plug, buy the right plug.

Great information Dany boy, be sure to post a link to any website info you may have to follow up on that information.

As for the lean/rich argument, let me clarify a little what I meant by a rich setting killing my plugs more then lean. Glow plugs really only last when an engine is tuned efficiently, if it is tuned incorrectly, the excess fuel, or lack there of, can harm the glow plug. But I found that most of the time the too lean setting is the easiest to diagnose, therefore happens the least. Especially with airplanes when I see a lot of guys tuning by noise and/or smoke, a too lean setting is rare compared to a too rich setting(In my experience, I'm not saying its true or false, just what I seem to see more so then the other) Depending on the climate, a engine running too rich can still run fine, with just a lack of power. To a novice user, this lack of power may be excepted as simply the way that engine runs, in the mean time, causing excess wear and tear on the entire engine, including the glow plug.

Also I noticed you said your plug was a long, double check and make sure your engine will work properly with a long plug, if your piston is getting too close to the glow plug, this could damage the element as stated in a previous post.

Good luck and good flying!

P.S., when you do solve the problem, let us know what you did!

I know that engine, or at least the ASP version, which I believe is identical. I've had two and both have had or quickly developed considerable slack in the bottom-end clearance to the extent that you can hear a click when turning the engine over. (never had any similar - or in fact any problem with other ASPs in that respect)

When running, if that clearance is too high, the click (knock) will send shock waves that may "rattle" the plug element causing rapid damage.

Another possibility, but less likely, is the out of balance prop you mention.

Check your big-end clearance - turn the engine over and feel for clearance as the piston goes over top dead centre. If you've made all the usual checks (fuel, head clearance etc) then that would be my bet.

thanx for everyone's input. the problem i had sounded very much like FKY1000's problem. the only time when i had plugs burn out on me was whenever i flew at the beach. i dont know what it is exactly but maybe the salt in the air or something there is not making my engine happy and burning my plugs. i'm no expert on glow engines (in fact this is my first glow plane), but since i've never had this problem when not flying at the beach, i know this has something to do with it.

also, i was running too lean before. apparently my muffler bolts also came lose and introduced an air leak into the engine and that's probably how it ended up running too lean (besides the high end being set too lean). while breaking in the engine, i ran it extremely rich (as specified by the manual), and i agree that it's almost impossible to burn plugs from running to rich (at least from my experience).

so the last two times i was out flying, i set my high end slightly on the rich side, made sure all the bolts were tight and had no problems at all. (i flew at the normal flying site, not the beach).

tomorrow i'm gonna try the beach again staying at exactly the same settings and if the plugs blow again, i'll know that it's definitely something in the air at the beach (probably the salt). if it flies fine, then i'll know that it was the running too lean that was causing my plugs to burn out. or maybe i just got a couple of bad plugs..... anyway, i'm just happy the problem's gone away. hopefully.....

brian

brian

I wonder if the air at the beach is not causing the mixture to go leaner and thus killing the plug indirectly ?

The reason that **overly** rich running is bad is that in ABC (tapered bore) motors the overly rich condition does not allow the motor to reach the correct operating temperature thus causing
accelerated wear. Even during running in the instructions will warn against this condition - for ABC motors obviously. The pinch you feel at TDC is much more pronounced at lower temps compared
to operating temps.

Let's review again my previous post:

OSMG6304- #1 Hot plug for low nitro (0-5%).
OSMG6308- #3 Medium plug for medium nitro (5-25%).
OSMG6312- #5 Cold plug for high nitro (25% +).


If you run high nitro % and hot temperature in your area you have to use hot plugs, they burn all the time....exactly like you are experiencing

If you use low nitro, hot plugs can be used.

In Montreal area in summer like 20-30Celcius or 70-85 F, I use OS #8 with no problem at all on my OS 46 FX.

I even fly in winter with no problem temp around -10Celcius

"If you run high nitro % and hot temperature in your area you have to use hot plugs, they burn all the time....exactly like you are experiencing"



I think you mean cold plugs for high nitro and hot temps.

I do believe he meant that you are burning plugs if you are using hot plugs in hot temp with high nitro. The solution would be to use a cold plug.

Good thing this topic came up. I've been having the same problem with a TT 46 on an Ultra stick. It destroyed one plane before I found out what all was going on. I rebuilt the plane and found that the original problem was due to the glow plugs burning out. I went through 3 of them in one day and still didn't figure out why it was happening. These were all different types and ranges of plugs too. I still don't know what's causing it.......[>:]

i guess there are a number of reasons why plugs burn out.

in my case, it WAS because i was running too lean. i guess the air at the beach had something to do with it, but i was already inadvertently
running too lean to begin with.

i've richened up my mixture, made sure that there were no leaks and since then have not burned any plugs. the engine is running great.

the only thing is i crashed last week! ran my receiver battery down too low and just lost it. oh well, i now have an excuse to get the model tech twister, which i've been wanting since it came out.

I would go to 15% nitro, I have ran 10% on them for years and thought the performance was good until I went to 15% synthetic, its much smoother. (I run only saitos so I dont know if it applys to brand X). And yes running too rich you can also go through plugs quickly. During break in when running the motor super rich I might go through 2 plugs before I get into the air. Then another one after about 4 or 5 flights until I begin leaning it out some. Dont ask for the scientific info on this, I just know it happens. And beleive me I have burned a lot of Nitro