Glow Plug Insert Leaking

I epoxied my Fireball shorts before using them, and they still blew the seals. Maybe motors with lower compression would last a bit longer.

If you stop the leak the pressure under the JV weld or epoxy will be about the same as in the cylinder because there is no flow and friction loss towards the seal. But this pressure (I assume the peak can be 15...20 bar or 200..300 psi when the engine runs) will throw the weld and epoxy off and the leak will start again..

I would buy new plugs knowing also, however, that COX engines will lose power with normal plugs and only turbo plugs with their tapered sealing tip can retain or even increase compression ratio.

Darren I am not sure about hobby supplies in Thailand and understand you need to cook with what you have there. But maybe ebay, or Bernie and Matt can still ship to you?

Thanks Andras
Will find out.

Talk soon
Darren

som glow plug leak not the coper seal on tread center pin loose leak is imposible to fix u can try to pres tight back with right tool dont no if is posible never try my self found 1 after hard crash engine start run bad wit closer look plug works ok just leak buble on very top on center pin seal it was .074 cox part not os

Got to watch out for those crashes. I was wondering if crimping the housing would work too. I have a couple cards of Fireball plugs. The old Goodyears ran well with the Cool plugs on high nitro.

I tried a fix on the plugs I have right now as want to get them... off the ground up in the sky!

I first pass put super glue into the seal around the leaking pin. Then put vacuum on the inside of the plug while the super glue was still liquid. This drew up a little bit of the super glue into the red insulation that was there. The leak stopped 100% I can assure you. Then after 8 hours I added a little epoxy all around the stud as suggested by some of you. Letting that cure as properly takes 24 hours. I will try them and hope the little sweethearts hold tight. In the battery clamp they still glow bright and orange so no residual super glue has leaked onto the filament. Hopefully this might do the trick.

When I looked up super glue has a useable temperature range to just over 300 degrees Fahrenheit. Epoxy is higher maybe closer to 400 degrees. Am I correct that the cylinders while running in an airplane with airflow over them will run in the mid 200 degrees? As far as I can tell maybe close to that. Well the burn marks on my fingers say hotter but...

I'll update after some flight time.
Ice

The dune buggy guys always are checking the head temps, and around 180 to 230 is normal. Maybe the plug would be a bit higher. I would assume that is in F degrees as they also test with a drop of water. I will be waiting for the results. Hope I didn't throw away my old leaky plugs. Probably did.

@aspeed wrote:The dune buggy guys always are checking the head temps, and around 180 to 230 is normal.  Maybe the plug would be a bit higher. I would assume that is in F degrees as they also test with a drop of water.  I will be waiting for the results.  Hope I didn't throw away my old leaky plugs.  Probably did.

Is anyone aware of any cox .010 glow heads leaking? That would help explain the lack of compression.

Happydad

Hi HappyDad
The heads I have for my .010 have never had leakage issues? One seized on pretty bad but not leaking.

Ice

@Iceberg wrote:Hi HappyDad
The heads I have for my .010 have never had leakage issues? One seized on pretty bad but not leaking.

Ice

FYI I was in Central Thailand in 1969-1970 with USAF. Worked with Opals and black Sapphires in the base gemshop to keep out of the heat.

Happydad

To see where the leaks are, you can squirt water or fuel over the head and turn the motor over with the prop to look for bubbles. Often the head gasket/shim has a piece of sand or dirt and it will leak from there, or there is a dent in the head or cylinder where it seals. A wet and dry test for the piston/cyl. is just add a drop or two of oil to the piston and see if it bubbles there. Pretty basic stuff that will tell a lot.

HappyDad
I hear you about the heat. I'm in Bangkok as hot as it gets. AC gem shop would be awesome escape.