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93 STS telling me to turn it off...no oil pressure


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so..here I sit. went to work yesterday and parked my caddy, a 93 black on black STS with 110000 clicks on it. previous owner had it until 5k ago, maintenance was meticulous, all done at the dealership. trouble started when I went to leave work and started up the caddy. No good!! I got the old no oil pressure, kill the motor msg. I did not believe it so I grabbed a flashlight and looked in the oil filler area while the motor was running to see if the msg was legit. bad bad news here, no oil. ok, I have read about over filling the crankcase with 10-12 additional quarts of oil. This is my hail mary plan. 2 certified mechanics pretty much told me that this car is done with no oil pressure so the overflow is my last hope. is this a good idea? how much would it cost me to rip into this bad boy and replace the pump? the car is really nice and has never leaked a drop of oil so I would hate to send it to the junkyard without exhausting every option to get this car back on the street. any ideas, info, whatever you can offer would be greatly appreciated. thank you.

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Oil pressure problems seem to be rare with a Northstar. Usually the problem is a bad pressure switch up by the oil filter. Before doing anything, I would put a pressure gauge on it and confirm the lack of oil pressure. It should only be 3-5 psi at idle. If you then suspect the check valve, over fill by 8 qts (total 15) and rev it a few times to 3-4K.

The oil pump is driven off the crankshaft and the dampener bolt must be torqued correctly (very high, 300 lb/ft or so). If not the pump will slip. Has the engine been out and opened up?

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WOW! got to work today and dumped an additional 12 quarts in the crankcase and fired it up. revved the motor and got nothin. all the while the valve train sounds like its gonna give up. I let it sit for a few hours and tried again, this time, bingo! oil pressure. runs rough but Im thinkin thats due to the extra oil. didnt drive it just at idle. I will drain it tomorrow and hopefully it runs like it used to. Thanks for the response.

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  • 2 weeks later...

So...The oil pump was definitely not working, no pressure and lots of top end motor noise. I used the overflow method as a last resort and it worked. After I got oil pressure the motor was still pretty noisey so I took it out and gave it some wot treatment to either make it better or blow it up. The motor runs as smooth as it ever has now, thanks again for the input, saved me a ton of dough and probably kept my car from the junkyard.

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