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Post by human on Oct 19, 2015 9:40:31 GMT -6
I did a little more research and DexCool was introduced in the 1996 model year, so it is NOT specified for a '95 Aurora. The old fashioned green coolant is indeed the appropriate choice for my car. DexCool (called "DexKill" by some of its critics) is a mixed blessing. Yes, it lasts longer than regular green antifreeze but not nearly as long as GM would have us believe. From what I've read, time rather than mileage is the operative factor as exposure to air has a nasty tendency to turn DexCool acidic over time and it eats away seals and plastic components. It is often pointed to as a major culprit for intake manifold failures, especially on 3800 Series II engines. There have been extensive discussions of this over on the pontiacbonnevilleclub.com board.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by human on Oct 21, 2015 8:39:24 GMT -6
Okay, so the pressure cap was not a 'magic bullet' fix, nor was I expecting it to be. Yesterday, temperatures crept back into the low 70s and my LOP warnings crept back as well but not until the outside temperature had fallen back into the upper 60s. I had two persistent LOP warnings at unusually long traffic lights during rush hour traffic with the outdoor temperature at 68 degrees and engine temperature at or slightly above 220 degrees. In both cases, engine temperature quickly fell back to slightly above 200 shortly after the light turned green and I started moving again. I also had one intermittent LOP as I was waiting to turn across a couple of lanes of traffic to get into the college where I teach. It came on for about two seconds and self-cancelled. I guess the lesson to be learned is it takes a little while at sustained high temperatures for the oil to actually thin out.
I drove the Aurora to work again today--third straight day--and had no problems. Afternoon temperatures are expected to hit the mid 70s, so it will be interesting to see how the oil pressure does. I had consistent LOP issues at or above 75 degrees with the old pressure cap in place. I've ordered a brand new ACDelco pressure cap of the exact type specified for the car. Tracking shows it'll arrive in today's mail. We'll see if it works any better than the junkyard replacement that I snagged Sunday, which is also a Genuine GM part but off of a different model car.
While it's progress, it's not perfection...
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by human on Oct 21, 2015 17:55:53 GMT -6
When the brand new pressure cap came this afternoon, I promptly put it on and drove the car in rush hour traffic with outside temperatures in the low 70s. The engine temperature stayed just a smidge over 200 degrees the whole time. Earlier in the afternoon, the car had done okay, albeit slightly hotter, in moderate traffic with the junkyard cap in 75-degree temperatures. Tomorrow is supposed to get up to 78 degrees and I've got a late afternoon class so I'll be in rush hour getting home. It'll be a good test for the new cap. At any rate, it's been a nice change of pace to park the Impala and drive the Aurora this week. But I'm still not pronouncing it fixed until I drive it successfully in at least 85-90-degree heat with the air conditioning going and I'm not putting any more refrigerant in it until next spring.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by Toronado3800 on Oct 21, 2015 19:38:21 GMT -6
Oh wow. Thanks for the series of updates.
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Post by human on Oct 22, 2015 15:51:49 GMT -6
Today was the warmest yet this week with the high topping 80 degrees as I drove home, but my engine temperature stayed right around 200-205 and no LOP warning (cue applause). Oil pressure did drop to the 8-9 psi mark at a few stop lights and I think I saw a couple of momentary dips to 7, but all in all, it's doing much better, especially considering that the last few times I drove the car in 75-80 degree weather before changing out the pressure cap, it consistently got LOP's. I'm still not going to pronounce it completely healed until I drive it in true summer conditions, but I'm feeling better and better about it.
The idea of replacing the water pump is still in the back of my mind and I may do that next summer if the LOP's return.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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tigger
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Post by tigger on Oct 23, 2015 18:06:41 GMT -6
Good to hear you're making progress! I did suggest a new cap in May, haha! Check your fans, replace your Tstat and reservoir cap! Water pump and Tstat would be a good spring project, keep at it...
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Post by human on Oct 23, 2015 22:02:44 GMT -6
Yeah, the thermostat has already been done and I think once I do the water pump, I will have replaced pretty much the entire cooling system. The car did okay this afternoon at long lights in 80-degree weather. It's interesting the more I drive it, the better it seems to do. For a while, I had gotten so disgusted with the car I didn't even want to drive it and had even stopped carrying the key in my pocket. I'm glad those days are over, at least for now.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by human on Oct 26, 2015 9:52:06 GMT -6
Yesterday, I got the first LOP I've had since putting the new pressure cap on. I was at a long red light at the top of an exit ramp with the nose of the car higher than the tail. Outdoor temperature was 71 degrees. Engine temperature rapidly spiked up from just a hair over 200 degrees to just over 220 and the LOP alarm went off. The alarm was persistent so I put it in neutral and gunned the engine to increase oil pressure and cancel the alarm. The light turned green a moment later and the temperature began to decrease almost immediately. No more LOP's the rest of the day or so far today.
It's interesting to me that yesterday's LOP happened when the outside temperature was 10 degrees cooler than it had been the previous couple of days when everything was fine. I've also noticed that the air coming out of the vents is quite warm, even though I've had the climate control is set all the way down 60 degrees. The AC is off since the refrigerant has leaked out and I'm not going to recharge it this late in the season. When we had a couple of cold mornings (30s and 40s) last week, I couldn't stand to have the temperature set even at 65. While 60 felt a little cool, 65 made the inside of the car feel like a blast furnace. I'll admit I'm pretty hot-natured, that was ridiculous.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by sall on Oct 26, 2015 10:13:55 GMT -6
Oil pump is behind the crank and turns with the crank. I read somewhere that if the crank is loose the pumps output can drop. Might want to check the torque. If that doesn't work then you have issues. Only going to get worse in warm weather and stop/go traffic.
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RCA1186
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Rob
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Post by RCA1186 on Oct 26, 2015 11:55:08 GMT -6
I've also noticed that the air coming out of the vents is quite warm, even though I've had the climate control is set all the way down 60 degrees. The AC is off since the refrigerant has leaked out and I'm not going to recharge it this late in the season. When we had a couple of cold mornings (30s and 40s) last week, I couldn't stand to have the temperature set even at 65. While 60 felt a little cool, 65 made the inside of the car feel like a blast furnace. I'll admit I'm pretty hot-natured, that was ridiculous. If the '95 uses the same setup as the later models, you could have a blend door or AC programmer problem. I had a faulty a/c programmer that made it so the temp settings would only change on the extremes...i/e heat would be on full from 90 all the way to 65, once you get to 60 it goes to cold(outside) air temp. Same going up, if you started from 60 it remained cold all the way until you hit 90)
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Post by human on Oct 26, 2015 19:52:39 GMT -6
Hmmmm. I don't much like the sound of that. How do I go about testing the torque and what should it be? More importantly, how do I adjust it if it isn't what it should be? Oil pump is behind the crank and turns with the crank. I read somewhere that if the crank is loose the pumps output can drop. Might want to check the torque. If that doesn't work then you have issues. Only going to get worse in warm weather and stop/go traffic. Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by human on Nov 16, 2015 10:41:18 GMT -6
Over the past month, I have been mostly using the Aurora as my daily driver and leaving the Impala at the bottom of the driveway. I've put a little more than 1,000 miles on it and have only had two LOP incidents since I replaced the pressure cap. Outside temperatures have ranged from the 30s to the low 80s. Ironically, the second LOP was yesterday and it was only 45 degrees outside. As with the previous one, I had just pulled off the highway and was at a traffic light. One thing I have noticed is that engine temperatures often peak and oil pressure correspondingly plummets when I'm out running errands, making stops, parking the car for a few minutes and getting back in and going somewhere else. The temperature gauge will often register higher after I get back in to go to the next place on my agenda than it did when I parked. The other thing I have observed is that there is a delay between the engine temperature rising and the oil pressure dropping. It appears to take a sustained high temperature to thin out the oil. I have several times seen the engine temperature rise above 210 degrees without the oil pressure dropping significantly. The car also seems to be doing better just by virtue of being driven regularly. Oil pressure mostly stays in the mid-20s to mid-30s at normal operating temperature when the car is moving and will usually maintain 9-12 psi at a stop light.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by Toronado3800 on Nov 17, 2015 9:53:50 GMT -6
My theory is your oil is:
Warmer and thinner after a long trip.
Or
Up at the top of the engine after revging her up on the highway.
I forget, have you fooled with synthetic or a thicker oil yet? It is only a band aid I will admit.
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RCA1186
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Rob
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Post by RCA1186 on Nov 17, 2015 14:08:08 GMT -6
Synthetic I would think would lead to less oil pressure (less flow resistance) although I haven't noticed as much at least according to my DIC.
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Post by human on Nov 17, 2015 17:11:58 GMT -6
I concur with the "warmer and thinner" hypotheses. When I first took the car to my mechanic after the LOP's started happening, the last thing he tried as somewhat of an act of desperation was to change the oil and put in 10W40. The car does use a little bit of oil so I checked it last week and wasn't surprised to see it was a little over half a quart low so I added some. What I had on hand was Havoline High Mileage Formula 10W30 so what's in the car now is 10W(not quite)40. My theory is your oil is: Warmer and thinner after a long trip. Or Up at the top of the engine after revging her up on the highway. I forget, have you fooled with synthetic or a thicker oil yet? It is only a band aid I will admit. Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by Toronado3800 on Nov 17, 2015 17:13:57 GMT -6
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Post by human on Jan 10, 2016 0:02:54 GMT -6
I've been driving the Aurora off and on since I last posted about oil pressure in mid-November without incident--until today, that is. I was out running errands, had three or four stops, was on and off the highway, and got an LOP at the top of the exit ramp coming back into my side of town. I think that's about the third one I've gotten at that same spot since October. The temperature outside was about 48 degrees and the engine temperature was just a nudge above 200 degrees. The rest of the way home--about three or four miles--oil pressure stayed in the high teens and low twenties when the car was moving and would drop down to about seven psi at traffic lights.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by Toronado3800 on Jan 10, 2016 0:06:43 GMT -6
How many miles do you figure you've put on it since the light first started coming on?
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Post by human on Jan 10, 2016 9:29:22 GMT -6
Since the first LOP last summer, I've driven it maybe a total of 1,500-2,000 miles. The problem started around the end of May and I pretty much quit driving the car until the weather cooled down in October. I doubt I drove the car more than 100 miles during the summer, because I couldn't go more than five or ten miles without getting an LOP. With cooler weather and after replacing the pressure cap on the overflow jug, I drove it daily from mid-October to sometime in November with the goal of putting 1,000 miles on it. Since replacing the cap, I've had maybe six or seven LOP's. Since about mid-November, I've driven it sporadically, putting maybe another 400 miles on it.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by sheaintheavy on Jan 10, 2016 12:51:59 GMT -6
Could the problem be the engine rpm drops too low at times? I had the LOP warning a few years ago, and I just slipped the gear into neutral to bring the rpm up a little and the warning stopped. I haven't changed anything in the time since except for water pump and thermostat, EGR valve, MAP sensor, and I now use 5w30 Mobile 1 high mileage synthetic all year, but no more LOP. The MAP sensor and EGR really helped with stabilizing the idle....
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Post by human on Jan 10, 2016 15:24:18 GMT -6
Could the problem be the engine rpm drops too low at times? I had the LOP warning a few years ago, and I just slipped the gear into neutral to bring the rpm up a little and the warning stopped. I haven't changed anything in the time since except for water pump and thermostat, EGR valve, MAP sensor, and I now use 5w30 Mobile 1 high mileage synthetic all year, but no more LOP. The MAP sensor and EGR really helped with stabilizing the idle.... I've done that a few times at long lights, drop it in neutral and goose the throttle a little. I have noticed sometimes that as the oil pressure drops into the single digits, the engine seems to run a little rough. My mechanic put a new thermostat on it last summer and I'm seriously considering the water pump as well. I'll definitely take the MAP sensor and EGR valve into consideration. UPDATE: After ascertaining that the parts were easily accessible and simple to install and that they aren't terribly expensive, I went ahead and ordered both the EGR valve and the MAP sensor. That can be a little half-hour project next weekend, weather permitting. I replaced an EGR valve about 30 years ago on my '77 Buick Skylark. My grandfather decided to turn it into a teachable moment and coached me through the operation, not that it was exactly brain surgery. Still, it's a good memory. I'll post back and let you know what, if any, effect that has. Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by human on Jan 12, 2016 14:56:28 GMT -6
I had another LOP this afternoon, similar conditions and location to the one Sunday morning, except I made it one more stop light past the exit ramp. That makes about half a dozen LOP's I've had within two blocks of the same spot within the past three months. Very odd. Thinking of recent posts in this thread, I immediately glanced at my tachometer when it happened and saw it was turning at barely above 500 rpm. The warning did self-cancel when the pressure went back up to 6 psi without my intervening.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by human on Jan 13, 2016 23:07:24 GMT -6
I had a pleasant surprise today when the mail came and in addition to my water bill, there was an EGR valve for the Aurora. It was a quick and almost easy installation. I say almost easy because one of the bolts that holds the valve in place fell down into the depths of the engine bay, never to be seen again. I'm really surprised there aren't any alignment pins to help keep it straight. That's how I lost the bolt was getting things lined up before I tried to start tightening the bolt. I'll head to the boneyard tomorrow and get another one. Actually, I'll get a couple of them in case I lose another. Then we'll see what, if any difference the new EGR valve makes. The MAP sensor should be here in a few days. That will be a snap to install.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by sall on Jan 14, 2016 16:34:34 GMT -6
Curious why you would expect a new EGR and MAP sensor would help low oil pressure? Faulty pressure sensor, thinning oil[heat], pump or worn bearings are the culprits...?
Anyways, here is a trick for you. Put a small rare earth magnet on your socket and it will hold the bolt securely.
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Post by Toronado3800 on Jan 14, 2016 17:23:56 GMT -6
I think they are under the belief the idle is low or eratic.
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Post by human on Jan 15, 2016 10:24:42 GMT -6
That is correct. I stopped by the junkyard on my way in to work today--it's right across the road from work--and grabbed a couple of bolts. I'll snug the EGR down properly this afternoon and run some errands in an attempt to more or less replicate the usage pattern that triggered the last LOP and see what happens. It's a barely scientific test, but we're grasping at straws here as I employ the 'Sherlock Holmes method' to eliminate the impossible so that whatever remains, no matter how improbable, must be the truth. I'm still waiting on the MAP sensor. Tracking shows a shipping label has been generated but the thing hasn't actually entered the mail stream yet. I think they are under the belief the idle is low or eratic. Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by human on Jan 31, 2016 21:08:56 GMT -6
So we had a nice, warm afternoon--high of 67 degrees--the last of the previous weekend's snow was gone and I finally had the EGR valve and MAP sensor installed so I decided to take the Aurora out for a spin. I intentionally made a few stops to set up the conditions under which LOPs occur and boy did they! I had several intermittent LOPs, which cancelled themselves in a few seconds, usually accompanied with the engine speeding up on its own. But at a couple of long stop lights, the LOP warning came on and stayed on until I dropped it into neutral and goosed the throttle. It was actually enough to make me worry that the oil level might be low, but I checked it a few minutes ago and the level was fine but the oil itself looked dirty. The DIC shows 62 percent oil life remaining. Bottom line there, the EGR valve and MAP sensor did not make one iota of difference. Fortunately, I didn't drop a whole lot of money on those two items. The Aurora will be pressed back into service for a few days next week (Feb 10) when the Impala goes in get the front bumper repaired. I just hope the weather's cold during that time.
Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by sall on Feb 1, 2016 9:17:05 GMT -6
Right those parts were just chasing a ghost IMO. Unfortunately I do not think it is going to get much better. At this point I would probably put the bandaid on it and run some good 5w-40 or 10w-40.
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Post by human on Feb 1, 2016 10:57:13 GMT -6
Right those parts were just chasing a ghost IMO. Unfortunately I do not think it is going to get much better. At this point I would probably put the bandaid on it and run some good 5w-40 or 10w-40. Although I'm still toying with the idea of putting a water pump on it, I'm rapidly getting to the point where I'm just going to have to "accept those things I cannot change" and either just drive the car in cold weather or just cut my losses, sell it, and let it be someone else's problem. Sometimes I think I really messed up by selling the LSS instead of the Aurora. Daily Driver: 2011 Impala LT Weekend Toy: 1995 Aurora
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Post by Toronado3800 on Feb 1, 2016 14:04:33 GMT -6
To get by longer I don't disprove of the thicker oils.
Any reasonable possibilities left uncovered? Is there a way to check our oil pumps w/o yanking the motor? W/O diagnosing it as a problem I would never recommend this, but I wonder if anyone makes a higher pressure pump for Northstars. Small Block Chevy's used to have seemingly more choices than necessary in the Summit and Jegs catalogs.
Somehow I, yup, me, ended up rebuilding an oil pump from a 60's vintage 460 Ford I believe it was in an equally huge Lincoln. It worked btw.
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