Glow plugs dieing in cool, wet weather?

[TK5310]

Motor is a TRX3.3 with THS pipe & motor saver filter, running on 25%.
Glow plugs are OS hot plugs.

I've never used many plugs, had plugs last for a few 2-4hr bashing sessions no problem.

Out last night, weather was cool (around 50-60deg) & it'd been raining quite a lot all day but cleared at night - lotsa water on the ground.
I killed 4 plugs in an hour.

I have no idea why, often I'd shut the car down to fiddle with something & it'd refuse to fire again - fresh plug & away she goes.
Also killed one mid WOT run.

Any ideas? - is the moisture in the air causing it?
Tune was good, around 240-260deg at the head, I fattened it up coz I figured it MUST be lean with the amount of plugs I was killing, got temp down to about 230 deg & she was still killing plugs.
All the plugs were burnt out mid coil.

The only other thing different was a new cooling head on the motor, but it was only to replace one with a stripped plug thread - just another stock trx3.3 head.

The other thing is a mate that was out with me was having the same problem, cept he killed 5 of em, another trx3.3 engine but stock pipe & filter.

 

[SchrodeMode]

Maybe water was getting through the filter? When you replaced the head, did you put the shim on the new one?

 

[TK5310]

Nah, inside the body was dry, fitted the new head with the new shim that came with it - same as the old shim.

I got no ideas.

 

[2revo1maxx]

Tune was good, around 240-260deg at the head QUOTE]

That's your problem right there^, you're tuning by temperature. A good tune at 50-60° would be more like 170-190°, but you should tune for performance, not temps.
Richen the engine until it runs pig rich, then lean it slowly back to performance. You should also look around for leaks, and make sure the exhaust system is good and tight.

 

[hamz9561]

Always try to tune for performance not temp. You'll get better results. Just try to keep the engine temps below 300° on the Traxxas engines.

 

[TK5310]

I was tuning for performance, just checking temp to make sure I didn't overstep it.
I guess the cooler air was just having more effect than I thought.
I had the HS 4 3/4 turns out, in slightly warmer air I usually run it about 4.5 turns out & she's sweet, figured an extra 1/4 turn out should be plenty - guess I was wrong.

Noted - make it pig rich when it's cold & lean it off a little from there.

 

[2revo1maxx]

When in doubt, always go rich.