new twin pipe exhaust and oil pressure/light prob

hello new here just bought a loverly 1986 1800gl from an old bloke with yes 60k on the clock.been doing few bits oil/filter change etc and just put on a loverly twin s/steel exhaust only prob now is when i rev over 4kish quite hard my oil light and buzzer come on i goes like **** as has weber conversion just wondering if im blowing up engine all levels great used 15/40 semi syn oil getting great throttle response any idea what the prob is cheers

Quick, simple diagnosis of Dynamic Oil Pressure Warning System by symptom.

Assuming your engine has oil and hasn't yet started knocking, most likely causes of oil lights/buzzers are in the warning system itself.

1) 2 seconds after 2000 RPM or more, light and buzzer come on, replace the high pressure switch.

2) Oil warning light on at idle, especially when hot, replace the low pressure switch.

3) No oil light blinking with key on, engine off, replace low pressure switch and/or repair light in instrument cluster.

4) If these quick tips fail to address oil warning light/buzzer issues, do not pass go, head immediately to your nearby mechanical oil pressure gauge store and buy a gauge. Buy or make a 10 x 1.0 mm threaded adapter. Test your oil pressure, cold and hot. Know what you are looking at

now symptoms i guess no oil pressure(oil light constantly on) at start up and loud ticking noises from top end.i suspect oil pump failure or headgasket get bit of water out of exhaust what confuses me is engine gets hot on top but sump and oil filter cold any ideas anyone cheers