HELP! Engine eating glow plugs!
 

hiya folks!

I have a mugen mbx5 buggy with a os v-spec (stock) engine.

The car has been in storage for a bit and i've recently brought it out to play.

during a session lasting about 4 hours. i went through about 10 plugs!

the plug filaments get desoldered or broken inside. so from the outside, the plugs look fine. sometimes, the filaments are melted into a lump.

i don't know what's happening to my engine, the compression is very good still. no play on the conrod.

this is with 2 shims on the head a silver thick one and a thinner brass shim.

the track features many jumps and i dunt believe i have geared my car wrongly. the clutch springs and shoes are new and dont look broken or worn.

the clutch bearings are fine too.



can anyone help with some advice??

thank you very much!

-alexander

I see two very important things that many of us overlook when asking for help in one of those cases:

1. I don't know which Combustion chamber height is when you use x shims. Measure it with a piece of solder wire. This is the way to know if you are too low or too high of height in your combustion chamber.

2. Pipe? Brand, model and type of manifold. Sometimes when a engine starts to eating glow plugs is because you are using a too short pipe.

Conrod is fine, but... how's going the main bearing? disassemble the engine and look to the main bearing, put your finger and see how it runs, it should run smooth. At the first doubt about the integrity of the main bearing, change it.

hhmm...
 

thanks for the reply,

the main bearing and front bearing were recently changed... just before i put it away for about a year.

the engine was oiled before i put it away.

the pipe i use is an old RB 2020 and manifold is medium length.

i'll go check on the shim thickness.

thanks again, can you think of any other reasons the glow plugs might be dying? they sometimes melt into a lump, sometimes just break inside. ( more melting into a lump though)

i use an adjustable glow plug heater like the one from Q-world. it connects to the 12 v battery, i've adjusted the voltage to barely glow the plug when starting cos one of mi mates said i might be pumping too much power through the plug. but the plugs are still dying..

i have a 1/10th onroad car as well with an os TZ engine. it runs perfectly well, no plug problems at all.

-alexander

My first guess would be that you need another 1 or 2 head shims. Do you know about what temp the engine has been running?

Hi, You state that your engine was stored for a while, and that it was oiled before you put it away. Any chance that the oil you used contained silicone? Just an idea I remembered from Ron Paris' tips. The silicone can cause plugs to pop.

If the engine was running fine before you put it away, and you are still using the same plug/fuel/shims I can't think of anything else.....:confused:

I agree with Doctor about checking your shims. If you are running 30% you need at least 1.0mm for shims. You sound as if your timing is way too advanced. Try a cooler plug. OS motors try the R5 or A5. (cold plugs) or no. 7 for turbo applications. They have thicker elements in the plug for high RPS and high nitro. Shimming it out and a colder plug will give you better performance and longer plug life.

hhmmm, i'll try that, thanks
 

hiya GHETTOTEACHER, royfan33 and THE DOCTOR

hhmm, i oiled it with wd40 and then marvel mystery oil.

i hope they dunt contain silicon.

as for plugs and shims, i'll go look into putting some more shims in and using a colder plug. thanks! i'll check back when i've tried it out!

-alexander