Oil pressure reading too high??

[Benzadmiral]

'Tis a bit nippy down here in The Swamp right now. These are the sort of temps you in New England or Minnesota would consider balmy, lows of 25 to 29 F. and highs around 45 F.

On my commute every morning, about 6 miles or 20 minutes into the run, I check my Driver's Info Center readings. Normally, in the 60 to 80 F. temps of most early Loozyana mornings, the oil pressure reads around 60 psi as I sit at the light, idling, and rises immediately as I accelerate. So far so good.

But yesterday and today, at the same point in my drive, it reads about 116 psi!

The car has 5w30 Napa Syn in it now, though I added .75 quart of 10w30 to top off about two weeks ago. The coolant is reaching the right temp of 192-195 F. as it always does, but the oil is reading thicker. Is it the outside temp that is keeping the oil pressure so high? If I drove the car longer, would the pressure come down?

One more detail: Sunday, warned about the coming chill, I topped off the battery, removed the clamps and brushed them up. Naturally I found that some of my electronic settings had been lost, like the clock and trip meters, but the oil life monitor was unaffected. Is it possible this affected the oil pressure reading?

 

[UNC017]

My rule is to never trust an electronic dash gauge for any sort of precision reading. I have no idea if your pressure is abnormally high or not, but my HUNCH would be that the abnormal cold has somehow changed the calibration of your electronic pressure sending unit, or outright caused it to fail.

 

[TallPaul]

That seems awfully high, even 60 seems somewhat high for idle.. Wonder what is the oil pressure spec on your car.

My F150 gets about 20 at idle and about 42 at speed.

 

[willix]

Never rely on a oem gages. If its PCM data then a sensor/sender may be at issue. It is possible incorrect volts, high or low may effect accuracy. Check the charging output. When was the last time someone had to top off the battery? This suggests to me the battery is cooking.

 

[Benzadmiral]

Originally Posted By: willix
Never rely on a oem gages. If its PCM data then a sensor/sender may be at issue. It is possible incorrect volts, high or low may effect accuracy. Check the charging output. When was the last time someone had to top off the battery? This suggests to me the battery is cooking.


The DIC readout on the battery is 13.6 volts, which I understand is a little high, but it's been like that since I've had the car. I check the battery every month, and have rarely had to add any distilled water.

That 60 psi for oil pressure is my memory of what it usually is. You know how you see something nearly every day, and when it changes you find you're not sure what the old setting was? It might be more like 35 or so. (On my W126 Mercedes, the oil pressure gauge was in bar -- approx. 15 psi per bar. It would start out cold at 3 bar, so about 45 psi, and sink at full warmup to 1.5 or so.)

ETA: Just talked to my regular mechanic. He thinks the 13.6 V is correct, and that since the other electronic gizmos are working, that it might well be the oil pressure sender. "Keep an eye on it," he says, "but it's probably not something to worry about until your next oil change."

 

[ARCOgraphite]

Pressure is too high - but most likely cause is faulty E-Gauge or sender. Second most likely cause is coolant in the oil - check this right away. A very very remote possibility is your oil pump relief is stuck. Is you filter weeping around the gasket?

 

[willix]

13.6v is normal output on that Buick. 60 psi@idle does seem high and may be related to outside temp in luzyanna. Does this 3.8 engine have a supercharger? I would be curious to know what the press.relief valve threshold is. Over 100psi seems excessive even at flat out WOT. Having the supercharger may explain the Higher pressures. I have no clue. Someone here will have better info on this.. I am generalizing at this point. 13.6 volt is normal for these cars.

 

[Benzadmiral]

Originally Posted By: ARCOgraphite
Pressure is too high - but most likely cause is faulty E-Gauge or sender. Second most likely cause is coolant in the oil - check this right away. A very very remote possibility is your oil pump relief is stuck. Is you filter weeping around the gasket?


Just checked the oil. With 3300 miles on it, it's a little darker than, say, spilled Coca-Cola, but definitely not milky or strangely colored. I might be able to squirm under and have a look at the filter this evening before it gets dark.

 

[Benzadmiral]

Originally Posted By: willix
13.6v is normal output on that Buick. 60 psi@idle does seem high and may be related to outside temp in luzyanna. Does this 3.8 engine have a supercharger? I would be curious to know what the press.relief valve threshold is. Over 100psi seems excessive even at flat out WOT. Having the supercharger may explain the Higher pressures. I have no clue. Someone here will have better info on this.. I am generalizing at this point. 13.6 volt is normal for these cars.

No, it's normally-aspirated. And as I corrected myself to say, I'm not *sure* that 60 psi was what I saw every day until yesterday -- so I know that's not much help.

 

[ARCOgraphite]

Had GM fixed the intake manifold coolant leak issue by '03? My throttle body fell off the plasitic intake on my 07 4.3L Chev W/T. GM has some issues. Prob them young guns pretending to be mech E but not dry behind the ears.

 

[TallPaul]

Get a mechanical gauge if you want to be sure.

 

[mechtech2]

13.6 seems about one volt too low, for a running system.

That oil sensor may whack out after a certain pressure is achieved, and not be accurate.
Too high is not a problem - too low needs checking out. This is because you have a reference from before.
I'd give it some time.

 

[Benzadmiral]

When the weather warms (which could be next week), I'll report back.

 

[ls1mike]

Every 3800 I have has was about 60 PSI at idle cold. That is 2 N/A cars and 2 Supercharged cars. The Supercharger shouldn't really make a difference. My bet is your oil pressure sending unit went bad. Easy fix and I have had to do it on 2 out of the 4 3800's I have had. I get mine from the dealer. Last time I got one it was 11 dollars.

 

[highmilegeguy]

Seems like 116 would explode the oil filter. Most are built with a margin of safety to, maybe, 100.

The oil pump pressure relief valve for most cars opens at 60-65.

 

[highmilegeguy]

""Had GM fixed the intake manifold coolant leak issue by '03? My throttle body fell off the plasitic intake on my 07 4.3L Chev W/T. GM has some issues. Prob them young guns pretending to be mech E but not dry behind the ears. ""

How does a throttle body fall off a intake manifold???

Sounds like a diyer was messing with it thinking he was a mech but was still wet behind the ears!

 

[GMBoy]

Originally Posted By: mechtech2
13.6 seems about one volt too low, for a running system.



Yes. With the engine running it should be around 14-14.5 volts. With the engine off it will show battery voltage so you'll see a 12 volt range.

 

[GMBoy]

I had this same issue with a 2001 Olds Aurora (4.0L V8) I used to own. The digital readout would occasionally show as high as 135psi! The first time it happened, I changed the oil filter and the issue went away. Then it reappeared several months to a year later and I did the same thing to "fix" it. Dummy me though I don't remember if the same make of filter did this both times!

 

[Benzadmiral]

GMBoy, mine is now showing a steady 130 psi, cold, idling, accelerating, whatever, it reads the same. The readout also proclaims that the oil pressure is "normal." Are there two circuits, one which monitors for low pressure and will trigger a light and warning message, and one which reads the actual pressure? If so, then the second is bad. If not, then how can the car's "brain" think that 130 psi is "normal"?

 

[willix]

The 96 Eldo I drive has read 13.6 after start cup and settles down to 13.3 or 13 .4 after running a while and this has been consistant through out the last 4 yrs I'v owned this thing. I don't read data unless its related to a active code. The batt was weak & replaced last summer and readings were unchanged. I'm curious to look at the oil psi after reading these posts. Its getting up to +10 today so maybe I'll start the thing up after sitting for 4 days outside.