Club G40 Forum

Club G40 => General Car Chat => Topic started by: Jezza-7 on April 28, 2010, 08:02:04 AM

Title: Melting pistons
Post by: Jezza-7 on April 28, 2010, 08:02:04 AM
Not something that has happened to me but was wondering what can cause a piston to melt?

And what ways can you prevent a piston melting?

Title: Re: Melting pistons
Post by: hayesey on April 28, 2010, 09:27:33 AM
without wanting to sound patronising but excessive heat causes it :) . Usually caused by the air-fuel mixture leaning out.  Usually caused by some kind of failure in the fuelling system or an unsuitable ecu map.
Title: Re: Melting pistons
Post by: hayesey on April 28, 2010, 09:30:46 AM
to avoid it it's good practise to replace both fuel pumps with new ones if they are old, get the injectors ultrasonically cleaned, routinely check the condition of all the fuel system components and replace anything that gets worn.  Watch out for the original metal crimps that hold parts of the fuel pipes together as they rust away and cause leaks which could lead to lean-outs. 
Title: Re: Melting pistons
Post by: hayesey on April 28, 2010, 09:32:53 AM
there's also a white push-fit connector behind the dash board going into the fuse box.  It's just push fit, there's no clip holding it in, make sure this is nice and tight if you've ever messed about with the wiring (or perhaps just check it anyway), if this comes loose and loses connection while driving the power to the fuel pumps cuts out.  Beavis at PSD once said that he suspected this was the cause of at least one melted piston he'd had in his workshop.
Title: Re: Melting pistons
Post by: Jezza-7 on April 28, 2010, 03:40:24 PM
Quote from: hayesey on April 28, 2010, 09:27:33 AM
without wanting to sound patronising but excessive heat causes it :) . Usually caused by the air-fuel mixture leaning out.  Usually caused by some kind of failure in the fuelling system or an unsuitable ecu map.

No worries, but thanks for advice.

I have a SNS chip stage 5 to suit G60 injectors, which have just been serviced by yoof so i dont think they will cause a problem. Getting a stack wideband a/f gauge so hopefully i will avoid the chance of something like that happening.

Car just hit 100k at weekend. Do you think it might be worth getting new fuel pumps?
Title: Re: Melting pistons
Post by: lance on April 28, 2010, 05:18:58 PM
yea mate well worth getting new fuel pumps!