Thanks everyone for the help, but i dont think its anything to do with wiring or battery anything along them lines. Believe it or not, i think its too much sump sealer thats been used when someone's resealed the sump. The reason i know this is because i used too much on our demo GT last week and it was making the same noise after I'd resealed it and it was running fine before hand. I was just hoping it would be something else as I dont like removing sumps lol. If too much sump sealer is used it apparently affects the Oil pump? Something like that. Doesn't quite make sense to me but anyway that