This is the TSB for the v8 engine but may apply to the V6 as well.
This bulletin is being revised to add clarification to correction. Please discard Corporate Bulletin Number 47-61-32A (Section 6 - Engine).
Some owners may comment on low oil pressure which may display a "Low Oil Pressure" message and/or a "Malfunction Indicator Lamp" (Service Engine Soon) telltale. Vehicle owners may comment that these telltale messages illuminate at engine speeds of 1000 rpm and above.
Lack of oil pressure may be caused by:
^ Particles from the manufacturing process sticking the oil pump relief valve, not allowing the valve to seal to its seat which does not allow the pump to prime.
^ A loose harmonic balancer bolt which will result in the oil pump not turning.
Ensure the harmonic balancer bolt is tighten to spec. The correct torque value for this bolt is 60 N.m (44 lb ft) plus 120°for 1993-95 engines with an M18 bolt and 50 N.m (37 lb ft) plus 120°for 1996 engines with an M14 bolt.
Notice : A small number of 1995 engines were built with crankshafts equipped with the M14 bolt. Identify the size of the bolt to determine the proper torque specification.
If the bolt is to specification, the cause of the low oil pressure is internal to the pump.
To remove particles from the relief valve in the oil pump, perform the following procedure:
1. Add an ADDITIONAL 10 to 12 quarts (liters) of engine oil to the engine. This will immerse the pump completely in oil.
2. Start the engine and repeatedly open the throttle (rev the engine) from idle to 3500 rpm. This will allow the pump to prime; cycling the relief valve forces any debris from the relief valve.
Important : Do not operate the engine above 3500 rpm. Doing so will aerate the engine oil and/or force excess engine oil into the PCV system. DO NOT DRIVE THE VEHICLE while the additional oil is in the engine.
After the engine has sufficient oil pressure, any valve train noise associated with this low oil pressure condition should not be evident upon restarting the vehicle and the low oil pressure and malfunction indicator lamp (service engine soon) messages should not remain illuminated.
3. After engine has sufficient oil pressure, drain the crankcase. Reinstall the engine oil pan drain plug.
4. Add 7 quarts of engine oil and check the oil level. Make sure the vehicle is on a level surface and the engine operating temperature is 1OO°C when checking the oil level with the engine stopped for 15-20 seconds.
Post by AuroraGirlFromMars on Oct 1, 2018 12:13:02 GMT -6
That is a LOT of extra quarts. However Im glad you posted that, I might try it... Im pretty sure the motor is worn but oil is cheap and worth a shot. And plus I just did an oil change so I could put this oil in another car.
But holy cow I did not expect that much extra oil.
I have also read that since the intake plenum is basically a plastic piece, I t can warp and cause a vacuum leak and basically cause all kinds of issues. I'm curious about all this my self. I have two auroras and my older one, it's an 01, is the one with this problem. The engine seems to be moving the oil fine, there are no knocking or clanking noises. it runs smooth at idle. It has gobs of power, in fact, it feels stronger than my 03. I'm just concerned because I would hate to need a new engine so soon here. But if I do, I'm definitely dropping in the 4.6 :-D
...And pretty sure manifold pressure should be 0 at idle... because the throttle plate being closed should be forcing a vacuum.
Sorry, skimmed passed this earlier...
Atmosheric pressure (@ sea level) is approximately; 30 inHg 14.7 PSI 100 kPa 1 ATM 1 Bar 760 Torr
Subtract your MAP reading (MAPinHg) from your Atmosheric Pressure reading (BAROinHg) to find how much vacuum you have. You may have to convert units depending on your scan tool...
Roo, a MAP reading of 18-23 inHg would probably be pretty close (I get ~18 on my 160k '01), but 18-23 PSI would probably push air/fuel OUT of the intake manifold, haha!
AG, a 5 PSI MAP reading would be ~10inHg, so 30 minus 10 equals 20inHg of vacuum. That's HUGE! Can you confirm 5 PSI? FWIW, a 0 (zero) PSI reading would indicate a 30inHg (14.7 PSI) vacuum, so, ...uh ...no. Pretty sure that would suck exhaust back into the intake. No bueno, Haha!
Post by AuroraGirlFromMars on Oct 2, 2018 13:58:07 GMT -6
That video doesn’t really help me at all.. but I did try the oil overfill. Did not work. Now my car has blue tailpipe smoke all the time (did before overfill) I think my engine Is on its deathbed. I’m going to try one more thing, and it’s pull off oil pan again and tinker down there and see if pickup tube is clogged. I doubt it but the gasket is cheap
The video actually does help. What he said made sense. The wire could be picking up resistance at some point in it's run causing this issue. And it's happening basically when the engines is hot. This situation would make the wires more pliable. plus all that heat cycling would make the wires brittle and probably cause breaks somewhere in the line. Just food for thought.
I agree the the video has some useful information. He points out that your possible culprits are: 1. A false reading, caused by: a. A bad sensor. b. A problem in one of the two wires to the sensor. 2. (If it's not one of the above, then) Actual low oil pressure, caused by: a. A oil pump problem. b. A problem with clearances in the engine bearings.
It's possible He has missed a cause, but I have not found anything else, in my searches.
I admire his camera/wrench skills. If I tried to video that, you would see what I intended about 10% of the time. The rest would be shots of my hand, my forehead, the nearest tire ---useless.
I'm a little bit mystified, by people's troubleshooting processes... I have limited skills, but the 1st thing I did was spend the $35 or whatever it was, to replace that sensor. I guess because he's an electrical guy, he preferred to crawl around, poke at the wiring, & spend $50 on tools he may go a long time before he reuses.
I didn't put a mechanical gauge on it or add 10 quarts of oil. I added a couple of quarts of heavier oil, not over-filling it, because I was looking to see about what percentage of the heavier oil it might take ---which, since it "fixed the problem," confirmed my car falls under #2. It became pretty much irrelevant if it was 2a or 2b, when I had other problems appear.
I havn't got the slightest idea about the manifold pressure, etc. on my car. I hope for your car, you are on to a solution, looking at vacuum leaks as a possibility.
The next step --for me-- would have been having the oil pump checked (or replaced), to confirm 2a or 2b. I really don't see a way to do that, where I don't feel stupid if it turns out that the pump was fine to begin with (if I had gone through those steps).
I expect every member we have ever had here will agree that it's sad that GM seems to have meant for the Northstar engines to be good while the cars were shiny and new, and limit the value of the cars when they get higher mileage. It also seems like they actively limited after-market, but that may just be how tight the engine bays are, so mechanics don't like to work in them. Maybe the limited life is just because new car owners needed to be very very careful with their routine maintenance, and most were not.
Personally, I'd be tempted to have an LS put in mine, but I don't believe GM makes a one for front wheel drive. I have a good idea what Lance went through shopping for & getting a new engine in his, since I got my parts car from him. That has made sitting, waiting, and taking time to look through alternatives more tolerable.
My thoughts based on the video, would have me run wiring direct from the PCM to the oil pressure switch avoiding heat sources and anything else that can introduce resistance into the wiring. I would do this on a test basis to see if it's the wiring path causing the issues. This way you can definitely rule out the wiring, the switch or the engine
Post by alexfinal500 on Oct 8, 2018 15:33:25 GMT -6
AuroraGirl, here's my viewpoint:
From what I am reading, I am guessing your engine is probably toast. But, what shape is the car in otherwise? If it is in good shape, I would say drop another 3.5 in it, or if you have access to another car for a while and the time, why not try to gain some more knowledge and get another 3.5, and like you were thinking, go rebuild it yourself? The only reason I would not rebuild the 3.5 that is in your car right now is because of the possibility of the block being worn out from the low oil pressure. I am also guessing that the Shortstar is a fairly inexpensive motor to get a hold of second hand. So you could always do that. Or if you could afford to, and if you were interested, go find another Aurora, but try a 4.0 this time, for no other reason other then why not?
Sorry to hear about the engine though. That's always a raw thing to have to deal with.
Post by AuroraGirlFromMars on Oct 8, 2018 15:41:59 GMT -6
Yeah... the engine I think suffered from unfrequent and possibly getting run with low oil. Because the engine was full of slude and oil would dirty within the first 50 miles and with how much oil the engines burn from stock wouldnt surprise me if it was worn way past normalcy. I can't find many auroras near me, sometimes I see a 1G here or there but at the moment a 99 saturn SW2 or 1998 buick park avenue will be my drivers, simply because I already have them and I just have to fix a miss fire.
Post by alexfinal500 on Oct 8, 2018 18:02:25 GMT -6
It sounds like your engine led a rough life before you bought the car. I'm in Michigan, and decent Aurora's are getting harder and harder to find here. Like you, before I found my 2003, all I saw were either a couple decent 1G's, or 2G's that just have had the snot beat out of them, and they were asking more for those cars then what I paid for my 03. Coincidentally, I just sold a 2000 SW2 this summer. Keep the oil topped up, and change the transmission fluid every 30k, and otherwise those are tough little cars.
Oil pump would require pulling the engine anyways, at that point might as well rebuild it all haha. If I were you, and had the room and time I'd head over to a picknpull and maybe gamble on a low mileage scrapper motor from a wrecked Intrigue or 'rora. Might get lucky.
That 3800 motor is no joke! I had a 99 grand prix GTP and my best time was 13.2 in the 1/4. My God how I loved that car... she was totaled. a piece of me died that day. My car was a factory freak. it ran 14.4 bone stock in the quarter. It didn't take much to get into the 13s either.