Ok. The rattling noise on first start-up is a piston to pin clearance issue. Most all of them do it the only way to get rid of the noise is to replace the pistons and pins with teflon coated ones and once the teflon wears off of those your noise is back. As long as the noise only last a short time you should be fine.
On to the p1189. When you tested the oil pressure did you test it at the oil pressure sending unit? In the gm manual they show a gauge that screws on were the oil filter goes and they check it there. On this tool is a valve That can block off the oiling system to check the pump if the pressure comes up the pump is ok and the problem is in the oiling system (i.E bearings, oil pick-up tube est.) It maybe worth having it checked and isolated.
You said that the intake gaskets had been replaced. I have seen were enough coolant had gotten in the engine to wash-out bearings. All that coolant in the motor gets all nasty. Can you take a light and look in the valvecover under the oil cap and see if it looks gumed up? You may want to try some rislone(not sure if I spelled that right) you put it in and run the motor for awhile before you change the oil and it breaks that stuff down. Make sure and inspect the terminals at the switch to make sure the are not spread open.
Thursday, July 19th, 2007 AT 5:45 AM