04 oil pressure

[My 1st mack]

I just bought a 2004 Mack with 427hp but  I bought it knowing it needed a turbo the guy I got it from said when that just before the turbo went it felt like the jake was on but he didn't have it on I checked under the valve cover and all looked good but now the oil pressure is about 12lb at idle he said it used to be about 40 before turbo went any idea what could be going on

[carlotpilot]

sounds like some rod or main brgs or both  are  on the way out .  can`t  imagine a turbo causing that much op drop

[fjh]

Something could be stuck in the oil pump relief valve that is a fare drop in pressure pull the pan and look!

[My 1st mack]

Thanks sounds like I will be spending more money