2002 90 hp Honda

[fighting-whitin]

Hey all,

I have got around to doing my yearly service on my engine.

Whilst changing my spark plug's I noticed my bottom spark plug has a white coloured type of carbon on it.

Straight away I thought I have a head gasket on it's way out, what do you's think, could it be a head gasket letting go or something else?

What is the easiest way to dignose the problem, would rather not pull the head off if it's not going to be a head gasket.

Many thanks in advance Mark

[Boatpride]

It could be aluminum corrosion, or that spark gap is not set correctly, hence white carbon deposit. If your engine is not over heating, then it's unlikely to be a head gasket issue.

[ondarvr]

If the head gasket is letting water in the plug will be very clean, with no deposits at all.

[Frosty]

It could be aluminum corrosion, or that spark gap is not set correctly, hence white carbon deposit. If your engine is not over heating, then it's unlikely to be a head gasket issue.

Could you please explain what you mean by aluminium corrosion, and why will a wrong set spark plug will have white carbon on it?

[pistnbroke]

the bottom cylinder cooling channels are prone to block up as any debris lodges here and the bottom cylinder could over heat giveing the overheated plug syndrome ...you been washing it out properly ???

and I agree with frosty again whats this aluminium corrosin on the plug crap and it certainly isnt the plug gap ..insufficient cooling of the plug nose or mixture problems .....

[fighting-whitin]

The engine has been flushed in fresh water after everytrip so I wouls say I have been cleaning it properly and it has never overheated before.

That was kind of my point, I thought that if I had a head gasket leak that my spark plug would be clean but it's not. It still has a slighty black look to it with a white crust.

I'm stuck on what to do at the moment, do I just gpo ahead and whip the head off??

Cheers Mark

[Frosty]

No No if you had a water leak it would misfire.

Difficult without seeing the plug but I would put it all back together and change the bottom injector with another cylinder of your choice , see if you can move the symptoms to another cylinder, then you know its an injector.

[Boatpride]

Frosty & Pistnbroke:

I stand corrected - not corrosion. Thank you for the steer!