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Post by human on May 26, 2015 17:52:58 GMT -6
So I posted in another thread about my little outing today to the N.C. Transportation Museum in Spencer. It's about 45 minutes to an hour from where I live. The car performed flawlessly most of the way down there and back, but almost as soon as I got off the highway and hit maybe the second traffic light, I got a 'Low Oil Pressure' warning on the DIC. I switched the DIC from displaying my average fuel economy (23 mpg) to showing my oil pressure. When the car was at a stop light, pressure would be around 7 psi but would immediately bounce back to between 18 and 21 psi as soon as I was under way again. I was only a couple of miles from home when this happened, so I just continued on home. The temperature was also up higher than I like to see it. The gauge usually sits a tad above the 200 mark, but this afternoon, it was up above the next thin line, maybe close to 240 degrees. Not overheating, but definitely hotter than it should be. It even smelled hot when I got out of it at my house. The symptoms, except for the temperature, remind me of an oil sensing unit failure I had on my '91 Cutlass Supreme.
I let it sit and cool off for a couple of hours and went back out and checked the oil. The dip stick shows the oil level at just above the 'add' line. I then cranked up the engine and let it run for a minute and the oil pressure level at idle (car in 'Park') held steady at about 23 or 24 psi. Looking underneath the car and on the driveway, there's no sign of a significant oil leak, although I can't get a clear view of the oil pan. Is the Aurora 4.0 engine as prone to upper pan seal failures as the 4.6L Cadillac Northstar on which it is based? I had that problem with my '97 Deville Concours and it was the reason I got rid of it and got a '95 Bonneville.
The car had an oil change a little more than 2,000 miles ago and the DIC is showing oil life at 56%, so it may be a bit premature for an oil change. I'm thinking I'll top off the oil and the coolant and monitor the situation for a little while.
For curiosity, what is the optimal oil pressure range on an Aurora?
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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Post by human on May 26, 2015 19:26:16 GMT -6
Update: I added a little over a quart of oil (Havoline 10W30 High Mileage Formula) and now the oil pressure is 46-47 psi at idle. I'll continue to monitor the situation but for now I'm going to hold off on a visit to the shop.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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RCA1186
Administrator 
Rob
Go Pack Go!
Posts: 4,837 
Staff Member
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Post by RCA1186 on May 27, 2015 7:10:51 GMT -6
Is the Aurora 4.0 engine as prone to upper pan seal failures as the 4.6L Cadillac Northstar on which it is based? Thats a BIG Y-E-S |
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Post by human on May 27, 2015 20:14:46 GMT -6
So I took the Aurora out for a little run to go get some dinner earlier this evening. I don't think I went ten miles. I checked the oil before I set out and the level was right at the 'max' line on the dipstick. The oil pressure was in the upper 50s as I started out and by the time I got to my destination it was in the low 40s. On the way back, it kept going steadily lower and lower, staying in the 20s and low 30s most of the way, dropping into the teens when I'd stop at intersections. I'll check the oil level in the morning and decide on further action then. I'd still like to know what the normal operating range is for oil pressure.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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randnon
Aurora Passenger
Posts: 246
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Post by randnon on May 27, 2015 21:50:25 GMT -6
Warm at idle I have seen as low as 12 -15 psi . Much higher at 2000 rpm cruising speed warm ~40 psi. I think the warning bell kicks in at 7psi. I would be more worried about the 240 deg temp. Perhaps that is what thinned the oil giving the low reading. I also have a 95 with ~110 m miles and my reading have been consistent over the years. Recently I switched to all reg oil vs using a synthetic blend in the past and noticed a increase in psi, ( i changed oils because of a bad leak ).
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Post by human on May 28, 2015 13:58:28 GMT -6
Thanks. Those readings sound consistent with what I had last night, so that makes me feel a bit better. I don't know why this car tends to run hot, but it has ever since I've owned it. Interestingly enough on my little run last night, it stayed steady just below 200. The car has a brand new radiator, installed in January, and is full up with fresh coolant. I don't think he changed the thermostat, though. I may go ahead and do that as a preventative measure. I'm going to go run it some more this afternoon to go get groceries and top off the fuel tank. I'm going to keep monitoring the situation. I think Tuesday's warning bell was a combination of the high temperature and being a quart low on oil. Now that I think about it, perhaps it was a vicious circle: low oil level raises the engine temp, which thins out the remaining oil, which reduces the oil pressure.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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Post by human on May 28, 2015 20:34:53 GMT -6
Turns out 5 psi is the magic number to set off the Low Oil Pressure alarm. I hit that while stopped at a long traffic light on the way home from my gas-n-grocery run this afternoon. The temp gauge topped out around 240 when that happened. I'm thinking a new thermostat might be a good first step toward breaking that cycle. An oil pressure sensing / sending unit might also be in order. Seems like a shop visit may be in order.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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Post by Toronado3800 on May 28, 2015 20:50:41 GMT -6
You're on the right track. It COULD be a t-stat and that is best tested by replacememt since ya almost have to remove the old one.
The oil is thinnest when hot and pressure is lowest at idle. 240 is too hot and the temp and pressure reading coinciding are a sign no one gauge is failing.
Do your engine temps just rise when you are at a light or do they raise when you are on the highway?
At a light the most common problems are electric fans and water pumps. At speed I believe if an air dam underneath breaks (in the snow or on a parking curb) we lose some control over how air flows through our radiator.
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Post by human on May 28, 2015 22:00:11 GMT -6
Ever since I've owned the car, the temperature gauge has been consistently staying right at or just slightly above 200. This week, it's crept up to that first hash mark past 200, sometimes even halfway to the next mark. Its when the temperature rises to a point almost halfway between 200 and the red zone that these alarm-bell-ringing low oil pressure episodes occur. This usually happens when the car is standing still at a traffic light. The temperature starts creeping up fairly rapidly and the oil pressure drops accordingly. Thanks for the tip on the air dams; I'll check that in the morning.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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tigger
Administrator
Posts: 2,844
Staff Member
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Post by tigger on May 28, 2015 23:32:11 GMT -6
Check your fans, replace your Tstat and reservoir cap!
Just curious, why did you replace the radiator?
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Post by human on May 29, 2015 8:07:08 GMT -6
I replaced the radiator because it was cracked.
I just talked with my mechanic and he's going to replace both the thermostat and the oil pressure sensor next week.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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Post by sheaintheavy on Jun 2, 2015 18:52:29 GMT -6
I had a similar experience shortly after purchasing my 96 a few years ago... Temps were in the 90s as I came off the expressway to stop and go / city driving. (oil pressure on the expressway usually starts in the 40s, but hasn't ever gone below 25.) At a stop, the low oil pressure warning came on and the engine temp was around the first line above 200, so I slid the shifter into neutral which let the engine idle at a little higher RPM - oil pressure came up enough to quiet the warning.
I had my mechanic check the oil pressure sending unit, and he reported that it read a couple pounds lower, at idle, than his shop guages. Other than that, the sender was working ok. Keep an eye on it, if anything changes. Over the years, the oil pressure/temperature characteristic remains constant, except that I haven't experienced any more warnings.
Regarding the lines on the temp guage - might want to compare them to a digital readout to see what value those lines really are. I was surprised to see that the line below 200 was reported as 190 digitally. I wonder what the line above 200 really is... I'll make a note of it this summer when it gets that warm (it may not be as high as it seems.)
Most important though, when you notice changes in your cars characteristics, you should have it checked out.
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Post by human on Jun 10, 2015 16:17:05 GMT -6
I just got off the phone with my mechanic and he did not have good news. He's replaced the thermostat, which has indeed helped the temperature, but the low oil pressure problem remains despite his putting in a new oil pressure sensor and replacing the oil with 10W40. It'll now run a little longer before the pressure drops off, but the problem isn't solved. His recommendation was to consider getting rid of the car before the head gaskets go. Needless to say, I'm kind of bummed.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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Post by Toronado3800 on Jun 10, 2015 18:02:48 GMT -6
That does suck.
Time to think about a few things. Your Aurora is not your daily driver if I remember but I like my Aurora and like having two cars myself.
Hownbad is it? What does your oil pressure read at idle after ten or so minutes @200 degrees?
Man, you could use it on a limited basis, trade it in at a "$3,000" minimum tade sale...
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Post by human on Jun 11, 2015 20:19:47 GMT -6
I haven't driven the car much at all since I got the Impala, but I do like having an extra car. I hot weather, I can't drive it across town without the low oil pressure warning coming on. I think I'm going to have to be making some hard decisions shortly. For now, the car is back parked in its accustomed spot at the bottom of the driveway and there it shall stay until I figure out what to do with it.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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Post by aj on Jun 11, 2015 22:08:10 GMT -6
I haven't driven the car much at all since I got the Impala, but I do like having an extra car. I hot weather, I can't drive it across town without the low oil pressure warning coming on. I think I'm going to have to be making some hard decisions shortly. For now, the car is back parked in its accustomed spot at the bottom of the driveway and there it shall stay until I figure out what to do with it. Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora Hey what brand was the oil sender unit? It also can be a bad batch of it too, that has happened before I know at my dealership they had went throught a whole box of the oil pressure sending unit and got a new batch and the first one did it. So there can be an issue with that! Maybe later on you can get yourself an engine and have repaired at a later time too since you have your newer Impala now that you drive. My Lucerne has been a let down to me lately the last few years and she is going downhill with some repairs that is just ridiculous. |
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tigger
Administrator
Posts: 2,844
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Post by tigger on Jun 11, 2015 22:42:54 GMT -6
Hey human, did your mechanic test the pressure with a mechanical gauge? |
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Post by human on Jun 19, 2015 15:32:22 GMT -6
I'm pretty sure he did. He's very thorough that way. Hey human, did your mechanic test the pressure with a mechanical gauge? Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora |
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Post by human on Jun 27, 2015 10:40:59 GMT -6
A string of thunder storms yesterday pushed the temperatures here down into the 70s for the first time in several weeks, so I decided to take the Aurora out for a little drive for the first time since I parked it in disgust. Oil pressure stayed between 16 and 25 psi. during the entire 45-minute drive but would drop to about 8 psi. at stop lights, just a hair above the point that the 'Low Oil Pressure' warning would trigger. The temperature stayed steady at just a tick over 200 degrees. I finally pulled the car back into the driveway and put it in 'Park' for a minute and within about 45 seconds, the temperature climbed just above the first thin mark past 200 (220?) and the 'LOP' warning sounded. The takeaway from that little experiment was that ambient temperature is a factor and I can't drive the car on 90+ degree days. I'd still love to identify and fix (if feasible) the root cause of the problem, although if I found the right toy to replace it I wouldn't hesitate to sell that car and let it become somebody else's problem. Meanwhile, I'm just thankful for the Impala, boring as it might be.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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Post by sheaintheavy on Jun 27, 2015 14:14:36 GMT -6
Oil pressure stayed between 16 and 25 psi. during the entire 45-minute drive but would drop to about 8 psi. at stop lights, just a hair above the point that the 'Low Oil Pressure' warning would trigger. The temperature stayed steady at just a tick over 200 degrees. Yup, this describes how my 96 behaves. Except for a particularly hot day, it hasn't tripped the low oil pressure alarm in 2 years. It's my daily driver and I use high mileage mobile 1 synthetic, 10-30 in the summer months. 5-30 in the winter and cooler months. I'll have to say there doesn't seem to be an oil pressure difference when leaving in the 5-30 during some hot spring days. The 5-30 tends to have a more uniform pressure in all Temps. I had an issue once with a bad oil filter in an 89 Trofeo (3800) I had, changed only the filter, and the oil pressure went back to normal. |
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Post by human on Jun 28, 2015 11:36:10 GMT -6
You had me a little excited when you mentioned the bad oil filter but when I checked the most recent service receipt, the mechanic had changed the filter along with the oil, even though it was way early for an oil change. Guess it's back to the drawing board... Yup, this describes how my 96 behaves. Except for a particularly hot day, it hasn't tripped the low oil pressure alarm in 2 years. It's my daily driver and I use high mileage mobile 1 synthetic, 10-30 in the summer months. 5-30 in the winter and cooler months. I'll have to say there doesn't seem to be an oil pressure difference when leaving in the 5-30 during some hot spring days. The 5-30 tends to have a more uniform pressure in all Temps. I had an issue once with a bad oil filter in an 89 Trofeo (3800) I had, changed only the filter, and the oil pressure went back to normal. Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora |
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Post by Toronado3800 on Jun 28, 2015 21:01:38 GMT -6
Oil pressure stayed between 16 and 25 psi. during the entire 45-minute drive but would drop to about 8 psi. at stop lights, just a hair above the point that the 'Low Oil Pressure' warning would trigger. The temperature stayed steady at just a tick over 200 degrees. Yup, this describes how my 96 behaves. Except for a particularly hot day, it hasn't tripped the low oil pressure alarm in 2 years. It's my daily driver and I use high mileage mobile 1 synthetic, 10-30 in the summer months. 5-30 in the winter and cooler months. I'll have to say there doesn't seem to be an oil pressure difference when leaving in the 5-30 during some hot spring days. The 5-30 tends to have a more uniform pressure in all Temps. I had an issue once with a bad oil filter in an 89 Trofeo (3800) I had, changed only the filter, and the oil pressure went back to normal. Hey hey, I loved my 89 Trofeo! In 2010 At 280k I drove it to Springfield and traded it in on my MarkVIII. |
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Post by sheaintheavy on Jul 1, 2015 9:51:57 GMT -6
Hey hey, I loved my 89 Trofeo! In 2010 At 280k I drove it to Springfield and traded it in on my MarkVIII. Awesome! I actually still have my Trofeo, but in 2011 I hit a deer. Parts are so hard to find, so I parked it and got the Aurora. It had 323k miles when I parked it, nothing major up to that point other than an intake gasket at 300k. Love that car. |
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Post by human on Oct 16, 2015 21:12:35 GMT -6
Well, for the past five months, the Aurora has basically been sitting at the bottom of my driveway with occasional little exercise runs that basically end once the oil pressure warning sounds. It was a little on the chilly side this evening (mid-low 50s) so I decided to take it out and see how much of a bearing temperature had on the oil pressure problem. Tonight was the first time since late May that I've been able to drive the car around without the oil pressure dropping below 12 psi! The engine temperature never topped 220, so there is definitely a connection. A couple of people I've talked with have suggested the oil pump as the culprit. How terrible is that to replace? I'm considering it but I do hate throwing good money after bad.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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randnon
Aurora Passenger
Posts: 246
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Post by randnon on Oct 16, 2015 23:00:42 GMT -6
The oil pump would be a big deal, and they are usually reliable. The 95's came with a higher flow oil pump to begin with. It is not available. I would look for a couple of other alternatives. One would be to disconnect the oil cooler using a filter adapter from a 98 or 99. Also find out why you are heating up to 220 deg. water pump? bad belt tension-er / belt, air deflector scoop in place. Are you using synthetic? Have you got any leaks under pressure? At higher RPM's what are your pressures at say 2000 and 3000 rpm ? Rich in Buffalo
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skizo
Aurora Passenger
WOT ... is there any other way?
Posts: 278
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Post by skizo on Oct 17, 2015 11:44:22 GMT -6
Temp is still too high, so I'd concentrate on the cooling system. Check for any noise around the water pump that would indicate excessive wear ... I replaced mine, and I haven't seen it crack 200F since no matter how hard it's driven.  If the water pump sounds ok, I'd also test the antifreeze if you haven't already done so, and plan on a good system flush in any case. Use the recommended DexCool at 50/50 and put a new pressure cap on the system. A lot of problems come about when somebody replaces a cap with some aftermarket cheepo that's not rated for the system. Stock cap should be 15 pounds. PS ... upping the oil viscosity is kind of a kludge for "fixing" an oil pressure issue. Your mechanic lost a few points here for that ... and while we're on the subject of oil, I'd recommend a quality high flow filter, as many of the aftermarket types can be restrictive ... |
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Post by human on Oct 17, 2015 19:26:54 GMT -6
I'll definitely try a new cap. Being a '95, the car takes the old fashioned green antifreeze. Dex came out a year or two later. I know it was in use by '97, not sure about '96. The system was flushed when the radiator was replaced last January and he may have even done it again when he replaced the thermostat. I agree about the thicker oil and my mechanic would as well. He said he did it as a last resort when he had run out of other ideas. Temp is still too high, so I'd concentrate on the cooling system. Check for any noise around the water pump that would indicate excessive wear ... I replaced mine, and I haven't seen it crack 200F since no matter how hard it's driven. If the water pump sounds ok, I'd also test the antifreeze if you haven't already done so, and plan on a good system flush in any case. Use the recommended DexCool at 50/50 and put a new pressure cap on the system. A lot of problems come about when somebody replaces a cap with some aftermarket cheepo that's not rated for the system. Stock cap should be 15 pounds. PS ... upping the oil viscosity is kind of a kludge for "fixing" an oil pressure issue. Your mechanic lost a few points here for that ... and while we're on the subject of oil, I'd recommend a quality high flow filter, as many of the aftermarket types can be restrictive ... Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora |
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Post by human on Oct 17, 2015 20:51:50 GMT -6
I was just looking at pressure caps on eBay and put a genuine ACDelco cap (RC74) on my watch list for $10.09 w/free shipping. I then got curious and took a look at the one on the car and its markings more closely resemble those of a Stant cap I also put on my watch list. Even if it's not the original, the cap has obviously been there a while as there's fair amount of brown residue on the underside; however, the inside of the tank appears clean. Would that residue interfere with normal operation?
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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Post by human on Oct 18, 2015 14:26:24 GMT -6
Today was such a nice day to be outside that I decided to indulge in one of my favorite outdoor activities--junk yarding. With the Aurora parked the past few months and the Impala being too new to really need anything, I just haven't had a reason to go lately. But I decided it would be worth the gate fee to see if I could find a pressure cap that would fit my Aurora's coolant tank. That actually proved to be a challenge since people at the yard apparently remove the caps as a matter of routine when they drain the cars of vital fluids, but I finally found one on a 2000-ish Chevy Malibu. At least I think it was a Malibu. It's a slightly different configuration, from the one on the Aurora, rated 15-18 psi and penetrating slightly deeper into the tank. There was a '98 Aurora nearby that was missing its cap but after a successful test fit, $2 got me a new(er) cap. I had driven the Impala to the junk yard so the Aurora's engine would be cold when I got home. I swapped on the cap and took it out for a drive. The engine temperature topped out at just over 200 degrees (maybe somewhere in the 205-210 range, assuming the temperature gauge is accurate) and the oil pressure stayed mostly in the 20s and 30s, which is much better than I've been seeing the past few times I've driven the car. At one long traffic light, it did drop to about 8 psi but quickly bounced back to 9 or 10 without my having to intervene. As soon as the light turned green and I gave it a little gas, the pressure was back in the mid-upper 20s. When I got home, I let the car idle for a minute or two. The temperature maintained and the oil pressure in park bounced between 9 and 10 psi.
I'm not going to call this 100 percent cured yet since it's not quite 60 degrees outside today, and ambient temperature is definitely a factor, but it's definitely progress in the right direction.
Daily Driver: 2011 Impala LT
Weekend Toy: 1995 Aurora
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skizo
Aurora Passenger
WOT ... is there any other way?
Posts: 278
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Post by skizo on Oct 18, 2015 22:24:58 GMT -6
Good to hear you're making progress ... I'd still go with a new OEM cap as our system is more sensitive than most. Also, I wasn't aware the Dex was a "new" thing ... I do know my '99 has a sticker recommending it's use.
Something else to put on your hit list ... check with your mechanic and see if he's sure the thermostat is installed correctly. That's something you could check yourself easily enough without losing too much coolant. There's a hole in the diaphragm that has to be up at the top for the thing to vent properly. Improper installation creates an air pocket that can prevent it from opening it when it should. Using a non-vented replacement will cause the same sort of issues.
I'd say your oil pressure is back in the ballpark. Mine warm idles at about 9-11 pounds, and average highway around 40-55 depending on load. Stomp on it, and I'll see 65-70 pounds. Crank it cold, and we're talking 90!
Oh. residue ON the cap shouldn't be an issue, but residue IN the relief section could definitely interfere with proper operation. Keep in mind, that same sort of gunk would be in the rest of the system too without regular flushing. One of the advantages of Dex is it's long life and less tendency to break down and create crud.
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