How Ironic. My oil light was with a Napa gold. 3200 into an oil change it started flickering then stayed on solid. Oil was full. PYB
Strange oil pressure experience
- Thread starter Stelth
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I had my VX's Oil Pressure Switch replaced, it had a small internal leak and I just replaced the thing. The replacement was wrong(I think for the 1.6L sized engines but nonetheless was what appeared to be a used part[in hindsight] from one auto part store's 'brand' to another auto store's 'brand' and reboxed)...
Long story short. I had the oil pressure light start to 'flicker' after a WOT and 2nd/3rd gear driving followed by downshifting up to a left-hand turn/slightly about a 10* degree incline. As I came to a stop in Neutral now, the light 'began' to flicker.
!?
For me, I changed the oil filter. At the time it was an Amsoil EaO20, at about 5,000 miles in on the filter. My engine 'may' be in somewhat of a cleanup mode. I still have the oil filter outside but have not cut it open as I'll need a real filter cutter for that housing.
What I can say is I returned the OPS to the auto store, complained it was re-boxed as I now realized and got the dealer OPS(not a sending unit mind u, I just have a dummy light).
The light never came on full and bright, but the 'flicker' sort of scared me. The UOA to follow showed normal 'wear', but idk. The oil pump might be lazy and if the filter 'was' loaded up it may have shown a lack of efficiency for the oil pump to handle relief bypass well?
Occasionally, I'll get the light go out like normal on a startup or 'restart'. The light will come back on for a brief second or two(at most) then return to being off as the engine starts idling. This is all within 5 seconds or so.
The more frequently this happens(light on/off/on/off again upon restarts mainly), I start wondering if the oil filter is being loaded up more. I have a Royal Purple, close to the same sort as the EaO. I'm approaching 4,000 miles in on this OCI.
Oh, the disadvantages of not having a reliable OPSU/gauge set up!
Then again, I have 260k miles and I could be looking at beginning of bearing failure allowing pressure drops/fluctuation.
Long story short. I had the oil pressure light start to 'flicker' after a WOT and 2nd/3rd gear driving followed by downshifting up to a left-hand turn/slightly about a 10* degree incline. As I came to a stop in Neutral now, the light 'began' to flicker.
!?
For me, I changed the oil filter. At the time it was an Amsoil EaO20, at about 5,000 miles in on the filter. My engine 'may' be in somewhat of a cleanup mode. I still have the oil filter outside but have not cut it open as I'll need a real filter cutter for that housing.
What I can say is I returned the OPS to the auto store, complained it was re-boxed as I now realized and got the dealer OPS(not a sending unit mind u, I just have a dummy light).
The light never came on full and bright, but the 'flicker' sort of scared me. The UOA to follow showed normal 'wear', but idk. The oil pump might be lazy and if the filter 'was' loaded up it may have shown a lack of efficiency for the oil pump to handle relief bypass well?
Occasionally, I'll get the light go out like normal on a startup or 'restart'. The light will come back on for a brief second or two(at most) then return to being off as the engine starts idling. This is all within 5 seconds or so.
The more frequently this happens(light on/off/on/off again upon restarts mainly), I start wondering if the oil filter is being loaded up more. I have a Royal Purple, close to the same sort as the EaO. I'm approaching 4,000 miles in on this OCI.
Oh, the disadvantages of not having a reliable OPSU/gauge set up!
Then again, I have 260k miles and I could be looking at beginning of bearing failure allowing pressure drops/fluctuation.
Originally Posted By: Stelth
I have a full-size GMC van with a 4.3l v-6. For most of the time that I've owned this vehicle, my oil pressure has been 20-25 psi at idle and 45-50 psi at speed, when fully warmed up. Not long ago, I had the oil changed by a quick-lube outfit with 5w30 Castrol and a filter that I can't remember the name of, but it was an e-core. Oil pressure was what I've come to expect until about 2000 miles into the OCI, when it dropped to about 20 psi at idle, and 35 psi at speed. I drove it for a while like this, but it made me uncomfortable, so I changed the oil again, this time with Max Life 5w30 and a Napa Gold filter. Oil pressure is back where I expect it to be, as above.
What gives?
What oil do you normally run, referring to the initial numbers you posted? My point is maybe you still have something that changed. If you normally run a generic 5w30 and your pressure is as initially stated, then you run the GTX and it starts falling off, there is definitely something that changed. If you change to MaxLife (a thicker 5w30), the pressure should be slightly higher than before, not equal. All this said, the numbers you quote are fine for the 4.3 but i would also be concerned about the relative and rapid change in oil pressure.
One thing to consider is engine temp. Sometimes the gauges on the GM's are not terribly precise. If the engine is running hotter it could cause your issue. I had this happen on my suburban 350. It dont take much of a temp increase to notice a drop in oil pressure.
I have a full-size GMC van with a 4.3l v-6. For most of the time that I've owned this vehicle, my oil pressure has been 20-25 psi at idle and 45-50 psi at speed, when fully warmed up. Not long ago, I had the oil changed by a quick-lube outfit with 5w30 Castrol and a filter that I can't remember the name of, but it was an e-core. Oil pressure was what I've come to expect until about 2000 miles into the OCI, when it dropped to about 20 psi at idle, and 35 psi at speed. I drove it for a while like this, but it made me uncomfortable, so I changed the oil again, this time with Max Life 5w30 and a Napa Gold filter. Oil pressure is back where I expect it to be, as above.
What gives?
What oil do you normally run, referring to the initial numbers you posted? My point is maybe you still have something that changed. If you normally run a generic 5w30 and your pressure is as initially stated, then you run the GTX and it starts falling off, there is definitely something that changed. If you change to MaxLife (a thicker 5w30), the pressure should be slightly higher than before, not equal. All this said, the numbers you quote are fine for the 4.3 but i would also be concerned about the relative and rapid change in oil pressure.
One thing to consider is engine temp. Sometimes the gauges on the GM's are not terribly precise. If the engine is running hotter it could cause your issue. I had this happen on my suburban 350. It dont take much of a temp increase to notice a drop in oil pressure.
Originally Posted By: yonyon
JHRZ2 is probably right. Something went wrong in the filter causing it to be bypassed. You ran some unfiltered oil for a little while, then you fixed it.
Yes a filter problem fits the symptoms; I've had it happen a couple of times.
JHRZ2 is probably right. Something went wrong in the filter causing it to be bypassed. You ran some unfiltered oil for a little while, then you fixed it.
Yes a filter problem fits the symptoms; I've had it happen a couple of times.
The system changes during driving/load conditions on the vehicle aside from normal filter bypass, etc. A loaded filter relying on it's bypass to keep oil from being filtered may cause a lazy oil pump or somewhat worn engine to respond poorly if stressed in this way? Suddenly the now invisible to pressure oil filter becomes a restriction point and the bypasses are relied upon, if not oil pump goes into relief mode and causing pressure drop?
Originally Posted By: jstutz
Guys, if the filter was bypassed, why would that lead to low oil pressure. Wouldn't that increase the pressure. There would be no loss across the filter.
Don't think of it as pressure loss, but pressure differential or pressure drop. Now, let's start with a zero restriction system where the pump dumps straight into the sump: there's no pressure differential between the pump output and the sump, so oil pressure is the same at both locations. The pressure at the sump is going to be approximately zero, so that's the pressure you have at the sump. Every restriction you add that creates more of a pressure differential will either lower pressure at the sump or raise it at the pump. The sump being at zero already, you get higher pressure at the pump. This continues as you add more restrictions increasing pressure differential until you reach maximum regulated pressure. In this simplified model, the filter will increase pressure at it's inlet side unless that is already at maximum and only then will it lower pressure at its outlet side.
Guys, if the filter was bypassed, why would that lead to low oil pressure. Wouldn't that increase the pressure. There would be no loss across the filter.
Don't think of it as pressure loss, but pressure differential or pressure drop. Now, let's start with a zero restriction system where the pump dumps straight into the sump: there's no pressure differential between the pump output and the sump, so oil pressure is the same at both locations. The pressure at the sump is going to be approximately zero, so that's the pressure you have at the sump. Every restriction you add that creates more of a pressure differential will either lower pressure at the sump or raise it at the pump. The sump being at zero already, you get higher pressure at the pump. This continues as you add more restrictions increasing pressure differential until you reach maximum regulated pressure. In this simplified model, the filter will increase pressure at it's inlet side unless that is already at maximum and only then will it lower pressure at its outlet side.
Originally Posted By: yonyon
Originally Posted By: jstutz
Guys, if the filter was bypassed, why would that lead to low oil pressure. Wouldn't that increase the pressure. There would be no loss across the filter.
Don't think of it as pressure loss, but pressure differential or pressure drop. Now, let's start with a zero restriction system where the pump dumps straight into the sump: there's no pressure differential between the pump output and the sump, so oil pressure is the same at both locations. The pressure at the sump is going to be approximately zero, so that's the pressure you have at the sump. Every restriction you add that creates more of a pressure differential will either lower pressure at the sump or raise it at the pump. The sump being at zero already, you get higher pressure at the pump. This continues as you add more restrictions increasing pressure differential until you reach maximum regulated pressure. In this simplified model, the filter will increase pressure at it's inlet side unless that is already at maximum and only then will it lower pressure at its outlet side.
^Which could then perhaps reveal a 'tired' oil pump that is just fine without a loaded up filter.
Originally Posted By: jstutz
Guys, if the filter was bypassed, why would that lead to low oil pressure. Wouldn't that increase the pressure. There would be no loss across the filter.
Don't think of it as pressure loss, but pressure differential or pressure drop. Now, let's start with a zero restriction system where the pump dumps straight into the sump: there's no pressure differential between the pump output and the sump, so oil pressure is the same at both locations. The pressure at the sump is going to be approximately zero, so that's the pressure you have at the sump. Every restriction you add that creates more of a pressure differential will either lower pressure at the sump or raise it at the pump. The sump being at zero already, you get higher pressure at the pump. This continues as you add more restrictions increasing pressure differential until you reach maximum regulated pressure. In this simplified model, the filter will increase pressure at it's inlet side unless that is already at maximum and only then will it lower pressure at its outlet side.
^Which could then perhaps reveal a 'tired' oil pump that is just fine without a loaded up filter.
I'm leaning toward the oil filter explanation. Next OC will be with Peak 5w30, a relatively thin 30 weight, and the ever-popular microgard filter, we'll see how that works out.
I will say this, I have a 'failing' IACV and it definitely can affect symptoms and feel, my idle gets near stalling at times and other days on cold starts does the 'rev rpm/fall rpm' like it's possessed.
I have the old oil filter and want to open it. No cutter for that amsoil EaO yet though.
I have the old oil filter and want to open it. No cutter for that amsoil EaO yet though.
Originally Posted By: jstutz
Guys, if the filter was bypassed, why would that lead to low oil pressure. Wouldn't that increase the pressure. There would be no loss across the filter.
Depending on how the oil circuit on the 4.3 is done, without the resistance of an oil filter I would expect a drop.
When my oil pressure changed I lost about 10pis across the entire RPM range. The gauge still came up but instead of going to say 40 it would be at about 30. I suspect for whatever reason the filter went into bypass or the element failed, because it happened fast.
Guys, if the filter was bypassed, why would that lead to low oil pressure. Wouldn't that increase the pressure. There would be no loss across the filter.
Depending on how the oil circuit on the 4.3 is done, without the resistance of an oil filter I would expect a drop.
When my oil pressure changed I lost about 10pis across the entire RPM range. The gauge still came up but instead of going to say 40 it would be at about 30. I suspect for whatever reason the filter went into bypass or the element failed, because it happened fast.
Originally Posted By: ltslimjim
Originally Posted By: yonyon
Originally Posted By: jstutz
Guys, if the filter was bypassed, why would that lead to low oil pressure. Wouldn't that increase the pressure. There would be no loss across the filter.
Don't think of it as pressure loss, but pressure differential or pressure drop. Now, let's start with a zero restriction system where the pump dumps straight into the sump: there's no pressure differential between the pump output and the sump, so oil pressure is the same at both locations. The pressure at the sump is going to be approximately zero, so that's the pressure you have at the sump. Every restriction you add that creates more of a pressure differential will either lower pressure at the sump or raise it at the pump. The sump being at zero already, you get higher pressure at the pump. This continues as you add more restrictions increasing pressure differential until you reach maximum regulated pressure. In this simplified model, the filter will increase pressure at it's inlet side unless that is already at maximum and only then will it lower pressure at its outlet side.
^Which could then perhaps reveal a 'tired' oil pump that is just fine without a loaded up filter.
I agree with this and believe i understand it. On the 4.3 I think the oil pressure sending unit is after the filter meaning if there is more differential pressure across the filter the gauge would read lower. So to me the filter could very well be the cause but not because its stuck in bypass which i believe on the 4.3 the bypass is located in the adapter the oil filter spins onto and not the filter. It would be more so because it was clogged for some reason and i believe the bypass don't open on the 4.3 until about 10 psi differential pressure. This is a great discussion.
Summary for how i understand it:
If filter bypass is stuck open, the oil pressure would read higher because there is no pressure drop across the filter.
If filter is restricted but not to the point of the bypass valve opening then you would see lower pressure at the sending unit therefore the gauge as well.
Originally Posted By: yonyon
Originally Posted By: jstutz
Guys, if the filter was bypassed, why would that lead to low oil pressure. Wouldn't that increase the pressure. There would be no loss across the filter.
Don't think of it as pressure loss, but pressure differential or pressure drop. Now, let's start with a zero restriction system where the pump dumps straight into the sump: there's no pressure differential between the pump output and the sump, so oil pressure is the same at both locations. The pressure at the sump is going to be approximately zero, so that's the pressure you have at the sump. Every restriction you add that creates more of a pressure differential will either lower pressure at the sump or raise it at the pump. The sump being at zero already, you get higher pressure at the pump. This continues as you add more restrictions increasing pressure differential until you reach maximum regulated pressure. In this simplified model, the filter will increase pressure at it's inlet side unless that is already at maximum and only then will it lower pressure at its outlet side.
^Which could then perhaps reveal a 'tired' oil pump that is just fine without a loaded up filter.
I agree with this and believe i understand it. On the 4.3 I think the oil pressure sending unit is after the filter meaning if there is more differential pressure across the filter the gauge would read lower. So to me the filter could very well be the cause but not because its stuck in bypass which i believe on the 4.3 the bypass is located in the adapter the oil filter spins onto and not the filter. It would be more so because it was clogged for some reason and i believe the bypass don't open on the 4.3 until about 10 psi differential pressure. This is a great discussion.
Summary for how i understand it:
If filter bypass is stuck open, the oil pressure would read higher because there is no pressure drop across the filter.
If filter is restricted but not to the point of the bypass valve opening then you would see lower pressure at the sending unit therefore the gauge as well.
Here is the diagram for the 4.3. The sending unit is after the filter on the top side of the engine.
http://www.chevytalk.org/fusionbb/showtopic.php?tid/192284/
http://www.chevytalk.org/fusionbb/showtopic.php?tid/192284/
Originally Posted By: jstutz
Here is the diagram for the 4.3. The sending unit is after the filter on the top side of the engine.
http://www.chevytalk.org/fusionbb/showtopic.php?tid/192284/
Interesting thread. Thanks. I'm about 3000 miles into my current OC of Max Life and Napa Gold filter, and the oil pressure reading has been consistent, including on some freeway trips of ~100 miles.
Here is the diagram for the 4.3. The sending unit is after the filter on the top side of the engine.
http://www.chevytalk.org/fusionbb/showtopic.php?tid/192284/
Interesting thread. Thanks. I'm about 3000 miles into my current OC of Max Life and Napa Gold filter, and the oil pressure reading has been consistent, including on some freeway trips of ~100 miles.
I have had this happen with Walmart SuperTech Synthetic 5w30.
It was definitely NOT the filter as every oil change I have done in my XJ is with the same FL1A filter.
Had it happen twice - after an all-weekend offroad session where the engine got REAL hot for MOST of the day, my idle oil pressure was around 18-22 or so.
As soon as I changed the oil, it was fine again ... until the next weekend offroad trip where the engine spent a lot of time at overheated temperatures.
I stopped having the problem when I switched to a HDEO. I'd really like to try a xw30 grade HDEO to see if I still have the problem.
It was definitely NOT the filter as every oil change I have done in my XJ is with the same FL1A filter.
Had it happen twice - after an all-weekend offroad session where the engine got REAL hot for MOST of the day, my idle oil pressure was around 18-22 or so.
As soon as I changed the oil, it was fine again ... until the next weekend offroad trip where the engine spent a lot of time at overheated temperatures.
I stopped having the problem when I switched to a HDEO. I'd really like to try a xw30 grade HDEO to see if I still have the problem.
Originally Posted By: Stelth
OK, let me try this again. The only person so far to offer any sort of a possible answer is JHZR2. Mostly I'm getting what I think are irrelevant questions.
So. What would cause an oil pressure drop of 10-15 psi when a vehicle is fully warmed up, with only a couple of thousand miles on the oil? And then the oil pressure goes back to normal with new oil and filter, and remains at the normal pressure for thousands of miles.
Let me ask the question again for possible penetration is this a factory gauge or an actual oil pressure indicator?
OK, let me try this again. The only person so far to offer any sort of a possible answer is JHZR2. Mostly I'm getting what I think are irrelevant questions.
So. What would cause an oil pressure drop of 10-15 psi when a vehicle is fully warmed up, with only a couple of thousand miles on the oil? And then the oil pressure goes back to normal with new oil and filter, and remains at the normal pressure for thousands of miles.
Let me ask the question again for possible penetration is this a factory gauge or an actual oil pressure indicator?
...and at idle isn't 18-22 'fine' anyway?
Originally Posted By: ltslimjim
...and at idle isn't 18-22 'fine' anyway?
It is within specification.
...and at idle isn't 18-22 'fine' anyway?
It is within specification.
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