Glow Plug Problems.....

[GilBeQuick]

Well today after running my buggy, I burnt up up 3 plugs! I don't understand how, the engine was running great at a good temp (around 250-260). This is an 8 Port Turbo with an OS 20E carb and an Ofna 063 pipe.
One plug just wouldn't ignite anymore, and the other 2 plug's coils were broken. One of the broken coils was just broken, and the other's coil was broken and looked like it had been mashed down up into the plug.
Aybody know what this means?
Any help would be much appreciated!

 

[GilBeQuick]

Anyone?
Does anyone know of a site that has pics of damaged plugs and explinations of them?

 

[SkyMaxx]

Does your engine require long plugs or standard length plugs? Is your engine a true turbo that requires the turbo plugs?

At that temperature, I am taking a stab at the fact that your engine may require a different plug than you are using.

Other than that, your symptoms are too varied to get a really good tell. The crushed coil indicates a rich setting. While the burnt up coil indicates too lean.

I think the first thing you may want to look into is exactly what kind of plug your manufacturer recommends for that engine.

 

[GilBeQuick]

10-4, I'll see what I can find out. Thanks

 

[olds97_lss]

Or, your running to high of nitro wich is causing to high of compression. This compresses the coil in the plug.

I haven't seen a compressed or broken plug yet. Mine just start to run funny and I replace them. But I only run 20% nitro. I once ran 25%, but it was only a gallon and it was my second gallon into the hobby. So I don't really know wether it was a bad thing or not.

 

[bomber]

In case you haven't seen this...

RCNitro's All About Glow Plugs - Glow Plug Help/Info

- bomber's

 

[militarymaxx]

Here's a glow plug chart featuring McCoy and OS plugs and theier applications.

http://www.hobbies-n-stuff.com/glow_plug2.htm

 

[Bill Hoskinson]

sounds like a main bearing going bad. Pull it apart, take the crank out, and put your pinky finger in the inner race of the main bearing. If you can feel any grit, or rough spots in the bearing, you need to replace it. Look for scrathes around the crank shaft where it spins in the crank case.

If you are running too much compression, (did you remove any head shims?) or if you are using a high Nitro Content/low oil mix fuel (25% and higher) you may need to switch to a colder plug.

 

[StrechM]

If you are using higher nitro content then you may want to reshim the cooling head to allow for more combustion area. I've had to do it on 2 of the last 4 engines. Usually a 1/10mm shim does the trick but check with the manufacturer first, they may recomend another thickness.

 

[GilBeQuick]

I've found the perfect plug! The Hyper .21 8 Port loves the McCoy MC-9! I'm running Odonnell 20%. Finally the engine doesn't blow plugs anymore (for the time being anyway HAHAHA), power is great and temps are right on track.

If you've having trouble finding a good plug for your 8 Port, try out the McCoy MC-9. If your hobby shop doesn't sell that brand, try a cold, long plug.

 

[SkyMaxx]

Had you left the word turbo out of your original post, I could have recommended just that plug. I run that engine and have tried a few McCoy plugs in it. The 9 works fine.

You might try some Fox Gold Series long plugs also. They are what I use now and work like a champ.

BTW, glad to hear you are running again.

 

[GilBeQuick]

Thanks. Yeah man, I actually wanted to run the Fox plug, but my hobby shop doesn't have cold in stock, only med and hot. I was running the Fox med plug before and it fouled out.
It's crazy how much difference a different temp plugs makes, and how it affects the way your engine works. I never really had to find the right plug before. When I needed a new plug I just got one according to the outside temp and it just seemed to work ok.

 

[Bill Hoskinson]

good deal! :hammer:

 

[GilBeQuick]

Bill, when you thought it might be a bad bearing, why? Is it because the bearing can fall apart and get into the engine?

 

[Bill Hoskinson]

All it takes is a little piece of trash in a main bearing race, and the bearings start to self destruct. Once the clearance between the races and the ball bearings increases beond a certain amount, you end up with the crank "wollering" around in the crank case. Depending on how bad the bearing is, and how tight the crank case fits around the crank counter weight, the crank may start to brush against the crank case. You can tell by checking the beargins, and by looking at the outside of the crank shaft inbetween where the 2 main bearings fit around it. If you see alot of scuffs, or scratches in the crank, it may be due to a main bearing going bad.

I have ruined glow plugs due to bad bearings before, and if you took the engine apart, you couldn't tell there was a problem, untill you checked the crank by taking it out, and swabbing the bottom of the crank case with a Q tip to see the aluminum dust.

Also, Pull start engines with internal one way bearings are notorious for eating glow plugs once the one way bearing has worn out. If and when you take your engine apart, check the one way bearing for the pull start. If it squeaks when you turn it on the starter shaft, its trashed, and it could also cause glow plugs failures.

 

[GilBeQuick]

Gotcha. That's something I've never heard before, or even ever thought about. Thanks for the advice.

Hey I DID learn something today!