Savage x f4.6 hissing

[Jaysavage2026]

Hello, I have a hpi savage x f4.6, I’ve noticed when it’s running there is a hissing sound from the top of the engine heat sink, I’ve tried the carb spray to see if there is a change in engine pitch, but nothing.

the idle gap is roughly 1mm by eye, I’ve got the lsn set so it idles, if I rev it the wheels turn fast and carry on turning for a little while even after I put the brakes on, it does eventually settle down, if it files for a little bit it seems to bog initially.

I’m not sure if it’s an air leak or normal? I can’t recall seeing an o ring behind the roto start plate or back plate if I’m honest, what should I do

 

[Vinni]

Hello, I have a hpi savage x f4.6, I’ve noticed when it’s running there is a hissing sound from the top of the engine heat sink, I’ve tried the carb spray to see if there is a change in engine pitch, but nothing.

the idle gap is roughly 1mm by eye, I’ve got the lsn set so it idles, if I rev it the wheels turn fast and carry on turning for a little while even after I put the brakes on, it does eventually settle down, if it files for a little bit it seems to bog initially.

I’m not sure if it’s an air leak or normal? I can’t recall seeing an o ring behind the roto start plate or back plate if I’m honest, what should I do

Av you checked it’s not leaking from glowe plug area ? N ya glowplug copper washer n the spinning wheels fing cud b broken clutch spring n any chance the hissing cud b spilt fual

 

[Jaysavage2026]

Av you checked it’s not leaking from glowe plug area ? N ya glowplug copper washer n the spinning wheels fing cud b broken clutch spring n any chance the hissing cud b spilt fual

Hi, I’ve not changed the glow plug but I have changed the copper washer, the clutch is all new as of today, the noise was there before changing the clutch shoes, bell and bearings.

It does sound to be from the glow plug area, but it’s the same plug as before which wasn’t making a noise that I can remember

 

[Jaysavage2026]

Hi, I’ve not changed the glow plug but I have changed the copper washer, the clutch is all new as of today, the noise was there before changing the clutch shoes, bell and bearings.

It does sound to be from the glow plug area, but it’s the same plug as before which wasn’t making a noise that I can remember

Also it’s not spilt fuel

 

[Vinni]

Also it’s not spilt fuel

Deffo not cross threaded plowplug - head button threads ? N revving 2 high cud be throttle linkage opening carb up does it do it with controller turned off ? Or Lowe speed needle 2 lean hope you get it sorted bro keep us posted is it new savage ? Or new to you

 

[Jaysavage2026]

Cheers I’ll try those tips, I’ll start with a new glow plug, if not I’ll change the o rings at the back plate and carb base, if it’s still happening I’ll take a look at the head shims, other than that I’m at a loss 😂 but I did spray carb cleaner and there was no change in pitch or revs. I’ll try doing the controller off too to see what that does, cheers

 

[guinnessdublin]

Have you checked cylinder head bolts are all done up tight?

 

[Jaysavage2026]

Have you checked cylinder head bolts are all done up tight?

Hi, yes I’ve checked and they are tight as they can be. I just thought I’d look again and I noticed when using the roto start I could feel air coming out of or near to the heat sink whilst turning it over.

I can’t recall seeing an o ring on the back of the roto start when I replaced the stater pin and spring, not sure if it needs one with the roto start or not?

I’ve just ordered a set of o rings - hpi 1450, I’m hoping they fit the f4.6.

I’ve also ordered a new under head, shims, bolts and glow plug. I’ll change The o rings on the carb too.

It does take a little while to start with the roto start from cold, not sure if that’s a sign of anything or normal?

 

[guinnessdublin]

Perhaps spray some washing up liquid over engine & see if it bubbles up anywhere?

 

[ohsnap]

Could it be the exhaust / torn exhaust gasket?
Are you seeing any evidence of the oil in the fuel being sprayed out anywhere?
Between the cooling head and block or the exhaust?

I’m not sure if it’s an air leak or normal? I can’t recall seeing an o ring behind the roto start plate or back plate if I’m honest, what should I do

The is no o-ring associated with a roto-start.
The o-ring on the backplate is internal to the crankcase.
So, you would not see it unless you removed the backplate.

If your engine is leaking air on the intake side of the cylinder, it would be running lean and odds are, revving high.