HPI F4.6 Fuel Leak & Discoloured engine head...

[FirsthandSnow]

Hey, I've just run my F4.6 Savage XL, its starts up fine, quite quickly despite being a little cold here today, and while I was putting the shell on, I noticed fuel bubbling from under the glow plug. I stopped the engine, took the plug out, gave the washer a wipe and reinstalled it. I then started her up again, and it was still bubbling. On a side note, the engine head is the silver F4.6 one, but its discoloured to a bronzy sort of colour. Although I have noticed it goes back to the silver colour once it is completely cool.
I don't know if this is all related...

Any clues?

Regards

 

[ninnon]

How hot is it getting to discolour the metal!? Have you got smoke coming out the exhaust at all times? Are you tightening the glow plug enough. It could just need a new washer or tightening...A video would help.

 

[FirsthandSnow]

There is always exhaust fumes coming out of the exhaust, as well as fuel, its running rich, all the needles are flush with the carb. Since getting it going I haven't tuned it. I'm using as OS8 Glow plug, so its a pretty warm one, but I live in England, and its February, its cold here I do have a cooler plug I could try...
I should really invest in a temperature gun...
But just so you know, Its the F4.6 using a stock HPI header and muffler, 17tooth clutch bell, 47tooth spur, 3 speed gear box, going to a 29/9 diff in the front and a 43 tooth diff in the rear. I'm waiting to change that diff, as soon as I can to another 29/9 set up
I'm not sure if the difference in gear ratio would put undue strain on the engine? But with the engine running rich it shouldn't be getting too hot, right?

Regards

 

[ninnon]

There is always exhaust fumes coming out of the exhaust, as well as fuel, its running rich, all the needles are flush with the carb. Since getting it going I haven't tuned it. I'm using as OS8 Glow plug, so its a pretty warm one, but I live in England, and its February, its cold here I do have a cooler plug I could try...
I should really invest in a temperature gun...
But just so you know, Its the F4.6 using a stock HPI header and muffler, 17tooth clutch bell, 47tooth spur, 3 speed gear box, going to a 29/9 diff in the front and a 43 tooth diff in the rear. I'm waiting to change that diff, as soon as I can to another 29/9 set up
I'm not sure if the difference in gear ratio would put undue strain on the engine? But with the engine running rich it shouldn't be getting too hot, right?

Regards

Have you tightened up the glow plug properly? and in the mean time, to check for overheating, try the spit test- just lick you finger and put some of the saliva on the cooling head, it should stay for a bit then evaporate, it should not boil instantly.

 

[FirsthandSnow]

Have you tightened up the glow plug properly? and in the mean time, to check for overheating, try the spit test- just lick you finger and put some of the saliva on the cooling head, it should stay for a bit then evaporate, it should not boil instantly.

Hey Ninnon, the plug is tight, I usually tighten the plugs down and then just a little extra force till I can't turn the wrench with my index finger and thumb, which has always worked for me on other trucks Thats a good idea, the spit test, I will give it a go maybe today sometime, but if it does boil off, and the carb settings are factory, what could be making it so hot....?
Regards

 

[ninnon]

Hey Ninnon, the plug is tight, I usually tighten the plugs down and then just a little extra force till I can't turn the wrench with my index finger and thumb, which has always worked for me on other trucks Thats a good idea, the spit test, I will give it a go maybe today sometime, but if it does boil off, and the carb settings are factory, what could be making it so hot....?
Regards

It is most likely tuning, or over revving due to clutch slippage.

 

[FirsthandSnow]

It is most likely tuning, or over revving due to clutch slippage.

hey, I tried a cooler plug, it took a little longer to start up, but once it was going it was fine. I've changed the washer on the plug and there was no leaking, so thats sorted. I tried the spit test, it didn't boil off right away, must have stayed for 5 to 8 seconds or so, although I hadn't thrashed the Savage, I'd let it idle with the odd burst of the throttle...
I'll just have to keep an eye to it I guess
regards

 

[ninnon]

hey, I tried a cooler plug, it took a little longer to start up, but once it was going it was fine. I've changed the washer on the plug and there was no leaking, so thats sorted. I tried the spit test, it didn't boil off right away, must have stayed for 5 to 8 seconds or so, although I hadn't thrashed the Savage, I'd let it idle with the odd burst of the throttle...
I'll just have to keep an eye to it I guess
regards

Follow this guide for tuning :
https://www.rcnitrotalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/