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Verify with a mechanical gauge. If it's actually that low, you likely have a worn bottom-end.
Low Oil Pressure
- Thread starter harbison
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Originally Posted By: TallPaul
Hooking up a manuan gauge is very simple, the tube hooks in where the sender for your electric gauge is not.
I don't know why I keep hitting t instead of w, should say "...where your electric gauge is now."
Hooking up a manuan gauge is very simple, the tube hooks in where the sender for your electric gauge is not.
I don't know why I keep hitting t instead of w, should say "...where your electric gauge is now."
Originally Posted By: TallPaul
Originally Posted By: TallPaul
Hooking up a manuan gauge is very simple, the tube hooks in where the sender for your electric gauge is not.
I don't know why I keep hitting t instead of w, should say "...where your electric gauge is now."
Once you have plumbed in the manual gauge, you first statement would be technically correct.
Originally Posted By: TallPaul
Hooking up a manuan gauge is very simple, the tube hooks in where the sender for your electric gauge is not.
I don't know why I keep hitting t instead of w, should say "...where your electric gauge is now."
Once you have plumbed in the manual gauge, you first statement would be technically correct.
IIRC you can install a "T"and run the dash gauge as well as a mechanical gauge.
Frank D
Frank D
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Throw in a quart of 20w-50 and see if it goes away. Then burn one and think about it.
I checked AutoZone yesterday for an oil pressure tester but they didn't have one. I will check the other auto parts stores. I checked a few things yesterday that may or may not mean anything. Started it up in the driveway and let it idle. For about 15-20 minutes the oil pressure stayed around 40. (It's about 60 degrees here.) It seemed to drop to 20 instantly rather than gradually. I don't know if the engine warmed up at this point or something switched. Continued to idle at 20 (about 750 rpms) Would go to 35 at 2000 rpms. After idling for about 30 minutes oil pressure was down to 15. The gauge is definitely responsive. I'm not sure about its accuracy, however. It doesn't bounce around or anything. Engine ran smooth. Oil is clean and full. No blow-by. I'll try to find a manual gauge. This is a very recent problem. I'll continue to sleuth it out. I'm not ready to pay someone $50 an hour to guess until I've run out of options.
Originally Posted By: Johnny
Originally Posted By: harbison
To Johnny: Pastor in Tahoka, Texas
Wow! You are out in the middle of nowhere. If my memory serves me correctly, you are about 25 miles west of Post, TX.
I asked for two reasons:
1. Originally being from Texas I was just curious.
2. You don't find to many ministers that are interested in oil. The Pastor of my church has two Lexus vehicles and he could care less. I tell him, you preach, I listen. I talk about oil, you listen, but he does not pay any attention to me. Good thing I listen to him.
to the site.
My preacher has a Dodge with the Cummins and NV5600. He makes his own bio diesel and uses Amsoil with a bypass filter! Very cool!
Originally Posted By: harbison
To Johnny: Pastor in Tahoka, Texas
Wow! You are out in the middle of nowhere. If my memory serves me correctly, you are about 25 miles west of Post, TX.
I asked for two reasons:
1. Originally being from Texas I was just curious.
2. You don't find to many ministers that are interested in oil. The Pastor of my church has two Lexus vehicles and he could care less. I tell him, you preach, I listen. I talk about oil, you listen, but he does not pay any attention to me. Good thing I listen to him.
My preacher has a Dodge with the Cummins and NV5600. He makes his own bio diesel and uses Amsoil with a bypass filter! Very cool!
I would try a fresh oil change with 10W40 and see if that fixes the problem. I could be that a quicky lube place put 5W20 in it. Or that the old motor is just ready for a thicker oil.
How is the engine temp -- is it running hotter than it should?
How is the engine temp -- is it running hotter than it should?
Originally Posted By: harbison
I'm not ready to pay someone $50 an hour to guess until I've run out of options.
Wow the small shops around here get between $85-$90/hour, and a dealership....Forget it........If you have a speed shop nearby they might have an OP gauge.
Frank D
I'm not ready to pay someone $50 an hour to guess until I've run out of options.
Wow the small shops around here get between $85-$90/hour, and a dealership....Forget it........If you have a speed shop nearby they might have an OP gauge.
Frank D
Originally Posted By: harbison
Yes, this is lower than normal.
Had oil changed less than 1000 miles ago. Hadn't had oil change in a while prior to that. This vehicle isn't driven that much. 5w30 (manual recommended) dino. Same place that I usually get my oil changed so wouldn't expect any change there.
A couple of questions:
1. How long is "hadn't had oil change in a while"?
2. Where do you get your changed at and what kind of oil and oil filter do they use?
Yes, this is lower than normal.
Had oil changed less than 1000 miles ago. Hadn't had oil change in a while prior to that. This vehicle isn't driven that much. 5w30 (manual recommended) dino. Same place that I usually get my oil changed so wouldn't expect any change there.
A couple of questions:
1. How long is "hadn't had oil change in a while"?
2. Where do you get your changed at and what kind of oil and oil filter do they use?
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Originally Posted By: harbison
For about 15-20 minutes the oil pressure stayed around 40. It seemed to drop to 20 instantly rather than gradually.
Ah-HA! Methinks we have our first clue...
Sounds like a wiring/grounding issue. Try removing and cleaning the connection at the sender. If that doesn't do anything, I vote for a faulty sender.
For about 15-20 minutes the oil pressure stayed around 40. It seemed to drop to 20 instantly rather than gradually.
Ah-HA! Methinks we have our first clue...
Sounds like a wiring/grounding issue. Try removing and cleaning the connection at the sender. If that doesn't do anything, I vote for a faulty sender.
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The abruptness of the event points to a sender/sensor. It should be cheap enough. Rockauto shows it from $20-$30
In all probability its the sender/sensor as more facts come to light. However its always a good idea when dealing with an oil pressure issue to have an idea via an accurate mechanical gauge just what the oil pressure is.
I remember many years ago when I first switched to a synthetic oil, pressure on a dash gauge had dropped and I was getting a knot in my stomach. The pressure did in fact drop, but was still safe, when verified with a mechanical gauge. Synthetic oils tend to show lower pressure than a conventional oil will, but they flow better, and its the oil flow that cools and protects an engine. I do remember you mentioning using conventional oil so the above doesn't apply to you, but I thought I'd toss it into the mix anyway.
I remember many years ago when I first switched to a synthetic oil, pressure on a dash gauge had dropped and I was getting a knot in my stomach. The pressure did in fact drop, but was still safe, when verified with a mechanical gauge. Synthetic oils tend to show lower pressure than a conventional oil will, but they flow better, and its the oil flow that cools and protects an engine. I do remember you mentioning using conventional oil so the above doesn't apply to you, but I thought I'd toss it into the mix anyway.
UPDATE: Changed oil pressure switch. Still drops. Maintains 50-60 when cold. Holds good at highway speeds but drops to "check guages" level at idle (5-10).
Changed oil after 2000 miles. Went with 10w40 instead of 5w30. No noticable difference.
Before trouble started, oil had not been changed in over year but only about 5-6000 miles, so it wasn't really too dirty or anything.
Problems seem to go back to oil change.
My question is What maintains your oil pressure when the oil warms up and thins out? My wife's suburban is 40 psi constantly.
Of course, her's only has 180,000 miles instead of 200,000 like mine.
Thanks,
Richard
Changed oil after 2000 miles. Went with 10w40 instead of 5w30. No noticable difference.
Before trouble started, oil had not been changed in over year but only about 5-6000 miles, so it wasn't really too dirty or anything.
Problems seem to go back to oil change.
My question is What maintains your oil pressure when the oil warms up and thins out? My wife's suburban is 40 psi constantly.
Of course, her's only has 180,000 miles instead of 200,000 like mine.
Thanks,
Richard
Originally Posted By: harbison
To Johnny: Pastor in Tahoka, Texas
Yes, this is lower than normal.
Had oil changed less than 1000 miles ago. Hadn't had oil change in a while prior to that. This vehicle isn't driven that much. 5w30 (manual recommended) dino. Same place that I usually get my oil changed so wouldn't expect any change there. Pressure gauge doesn't come up automatically.
I see from a later post that you changed the sending unit with no change in behavior. I'd go further and say buy an inexpensive mechanical oil pressure gauge and see what it reads. There are too many other things in the chain of electric (especially factory electric) gauges that can go screwy on you. Mechanical gauges, even cheap ones, are typically fairly accurate.
It COULD be a bad filter too- maybe collapsed filter media. I'd say its worth a few bucks to change the filter and replace a quart of oil to see if the behavior changes.
I've seen at least one vehicle that would lose oil pressure after running for a while, and it was such a large accumulation of gritty blow-by deposits in the oil pan that it would plug the oil pickup screen after a few minutes! (Believe it or not, after a redneck oil pan scraping and a fix to the PCV system, that engine is still running at over 230,000 miles).
To Johnny: Pastor in Tahoka, Texas
Yes, this is lower than normal.
Had oil changed less than 1000 miles ago. Hadn't had oil change in a while prior to that. This vehicle isn't driven that much. 5w30 (manual recommended) dino. Same place that I usually get my oil changed so wouldn't expect any change there. Pressure gauge doesn't come up automatically.
I see from a later post that you changed the sending unit with no change in behavior. I'd go further and say buy an inexpensive mechanical oil pressure gauge and see what it reads. There are too many other things in the chain of electric (especially factory electric) gauges that can go screwy on you. Mechanical gauges, even cheap ones, are typically fairly accurate.
It COULD be a bad filter too- maybe collapsed filter media. I'd say its worth a few bucks to change the filter and replace a quart of oil to see if the behavior changes.
I've seen at least one vehicle that would lose oil pressure after running for a while, and it was such a large accumulation of gritty blow-by deposits in the oil pan that it would plug the oil pickup screen after a few minutes! (Believe it or not, after a redneck oil pan scraping and a fix to the PCV system, that engine is still running at over 230,000 miles).
Originally Posted By: harbison
My question is What maintains your oil pressure when the oil warms up and thins out? My wife's suburban is 40 psi constantly.
Of course, her's only has 180,000 miles instead of 200,000 like mine.
When hot, your oil pressure should NOT remain constant as you go from idle to high RPM- it should ramp up until the engine's oil pressure regulator kicks in, and then it should hold constant.
I presume you aren't aware that not all factory "oil pressure gauges" are actually real gauges. Some of them are wired so that they are, in effect, just a mechanical oil pressure light- when the sensor detects more than ~5 psi, contacts close and the gauge flips to a pre-set reading (usually around mid-scale or "40 psi.") If the sensor ever drops to below ~5 PSI, the pseudo-gauge will drop to 0 and the "check gauges" light will come on. Fords were notorious for having this kind of non-gauge back in the late 80sa and 90s, but I've seen them on other brands as well. I suspect this is what your wife's Suburban actually has. Other factory gauges, sometimes in the exact same model car but a different year, will actually be fairly accurate. My '99 Cherokee's dash gauge tracks almost exactly with a mechanical gauge.
My question is What maintains your oil pressure when the oil warms up and thins out? My wife's suburban is 40 psi constantly.
Of course, her's only has 180,000 miles instead of 200,000 like mine.
When hot, your oil pressure should NOT remain constant as you go from idle to high RPM- it should ramp up until the engine's oil pressure regulator kicks in, and then it should hold constant.
I presume you aren't aware that not all factory "oil pressure gauges" are actually real gauges. Some of them are wired so that they are, in effect, just a mechanical oil pressure light- when the sensor detects more than ~5 psi, contacts close and the gauge flips to a pre-set reading (usually around mid-scale or "40 psi.") If the sensor ever drops to below ~5 PSI, the pseudo-gauge will drop to 0 and the "check gauges" light will come on. Fords were notorious for having this kind of non-gauge back in the late 80sa and 90s, but I've seen them on other brands as well. I suspect this is what your wife's Suburban actually has. Other factory gauges, sometimes in the exact same model car but a different year, will actually be fairly accurate. My '99 Cherokee's dash gauge tracks almost exactly with a mechanical gauge.
440 Magnum,
I considered the bad filter, which is one reason I had the oil changed again. On the crud in the oil pan, would that cause a consistent problem or sporatic?
It runs great otherwise. My last suburban (93) had 275,000 miles on it when I sold it and still ran great. I need to find a mechanical gauge. AutoZone didn't have one, maybe other parts stores would.
I considered the bad filter, which is one reason I had the oil changed again. On the crud in the oil pan, would that cause a consistent problem or sporatic?
It runs great otherwise. My last suburban (93) had 275,000 miles on it when I sold it and still ran great. I need to find a mechanical gauge. AutoZone didn't have one, maybe other parts stores would.
FWIW, when I bought my '99 Cherokee (with a fairly accurate gage, as stated above), I saw it go as low as 15 PSI at idle when hot, and up to around 45 PSI when under load. 15 PSI seemed low to me, but a quick check of the service manual revealed that as low as 13 PSI at idle is normal. After changing the oil and filter for the first time (it had a Fram and who knows what oil), I've never seen it go below 25 PSI at idle and have seen it as high as about 55-60 PSI when under load. I'm using 10w30 and have used both Mopar and Purolator filters.
The point of all that was, maybe a simple oil change will clear it up.
The point of all that was, maybe a simple oil change will clear it up.
mstrjon32 - I just had the oil changed again but that didn't seem to help.
1sttruck - oil pressure relief valve? I'll have to get a manual and find out where that is.
Going down the highway it maintains about 40 psi but once you come to a stop, it goes down to nearly nothing.
1sttruck - oil pressure relief valve? I'll have to get a manual and find out where that is.
Going down the highway it maintains about 40 psi but once you come to a stop, it goes down to nearly nothing.
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