[Hawk]

Hi everyone,
Here I am with another problem...as usual.My problem is I keep blowing glow plugs....I have a GMS .47 and a Webra speed 40 high output heli motor with a plane head.
I get about 5 flying hours out of a plug and then it stops working... I use Omega 15% nitro in both. the other day for instance I took my seamaster out(Webra). I adjusted the high speed jet to 2 clicks back from top RPM. Flew a few circuits some touch and goes on the water. then in the air it started to act up ...wouldn't give full power, running rough, so I brought it in. As soon as I let the rpm get down it died. I put my glow starter on and it fired right up took the igniter off and it dies. so I changed the plug and as good as new.looking at the plug it is alittle black. the coil is shiney. and almost identical circumstances with the GMS .47 but it flies mostly at the field.Has anyone else had similar problems. or can help me figure mine out.
Hawk

[ronm]

It is probably from running too lean. That is the biggest plug-killer. You may have to richen more the 2 clicks to compensate for leaning out as the tanks empties.
Also check that your fuel tank is not mounted too high, as that will cause excessive leaning as the flight progresses.
What type of plugs are you using? Generally, the more expensive plugs are worth the money.

One other thing that will blow plugs is contaminants in the fuel. Silicone lubricant is the worst. It will nuetralise the platinum on the coil, and that is what reacts with the methanol to make your engine go.
Make sure any after-run oil you use does not contain silicone.

Hope this helps,

Ronm

[nony]

If you use WD-40 or something similar as an after run oil, it will kill the platinum on the plug.

As mentioned above, running lean and hot will do the plugs in as well.

On my GMS, I had to add of the head shims to get it to run properly...after that it was the best engine ever...a half flick on the spinner was all that was needed to get it running..

Some of the glow plugs supplied with the engines when you buy them are not the best. Some manufacturers (MDS comes to mind) tell you to replace the plug once the engine is broken in...

Again....an $8 OS A3 plug (or similar) will out last several bargain basement ones. You are paying for more platinum on the plug element, and this makes a difference....

[Hawk]

Hi,
The last plug I blew was my 4th on two engines. each one after approximatly 5 hrs.
I am using Fox gold series R/C Long #41602
Hawk

[FaceDeAce]

Hi,

Running lean and running higher nitro in an engine not designed for it will cause you some trouble. To solve the high nitro, some people add shims. I advise to just stick with the lower 5-10% nitro for sport flying. Running an overly "hot" plug can also be an issue.

In my beginnings I had similar problems. As soon as I switched to using exclusively OS#8 and OS-F plugs for sport flying, the plug problems went away. Actually, it has been a very long time since I've replaced a plug. Go with the quality plugs. Sure they cost 2 or 3 times more, but they last at least 10 times longer.

Your problems may be a combination of all of the above. I'd start out with a known high quality plug. (some of my early problems were actually with a Fox) If you blow the new plug, then I'd drop nitro. If you still have problems after that, then you have a fuel delivery (lean) issue or a contaminant issue.

Food for thought, and I hope this helps you out!

CP

[FaceDeAce]

An afterthought:

I notice you mentioned flying off of water. How old is your fuel jug? where is it stored?

Methanol actively absorbs water from the air. If your jug has been around awhile, stored in a humid environment, cap not sealed well, etc -- then there is a very very good chance of your problems are related to water build up in the fuel. You may want to try a new jug as well.

[Hawk]

Hi,
Thanks for the reply.
I am flying off the water about 30% of the time....and the fuel is a new bottle.Ive flown about 15 hrs this yr. One of our flying gurus suggested I lean my idle abit. so I have and we shall see if that makes a difference.
Hawk