Low oil pressure....sometimes

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iamdub

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Will wait for you to report your findings on this.

If I had an oil pan handy, I'd be on it. If I think about it when I do my delete, I'll get some figures. I'm sure someone here has an oil pan sitting around, though.
 
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DougAMiller

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OK, I measured the angle that I had the nose pitched down. Combining the slope of my driveway and the height of the ramps, the rear wheels were about 18 inches higher than the front. So, conditions were the angle was about 9° and I had it overfilled by 2 quarts. I've never leveled it from the factory rake, so add that in. It's what, 1° or 2°? And finally, I've never paid any attention to whether the engine sits parallel to the frame on these. I've known of some vehicles that the engine sat tilted back slightly, so if there is any tilt that should be factored in.

Funny how so few degrees of pitch feels so steep when you are sitting inside.
 

iamdub

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OK, I measured the angle that I had the nose pitched down. Combining the slope of my driveway and the height of the ramps, the rear wheels were about 18 inches higher than the front. So, conditions were the angle was about 9° and I had it overfilled by 2 quarts. I've never leveled it from the factory rake, so add that in. It's what, 1° or 2°? And finally, I've never paid any attention to whether the engine sits parallel to the frame on these. I've known of some vehicles that the engine sat tilted back slightly, so if there is any tilt that should be factored in.

Funny how so few degrees of pitch feels so steep when you are sitting inside.

I'm gonna say the factory rake cancels out the slight angle of the engine for (1) it's negligible and (2) it simplifies what shouldn't be so complicated in the first place.

If I'm in the area this weekend, I'll stop by a friend's house that I'm sure has at least one oil pan kickin around his shop.
 

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I'm gonna say the factory rake cancels out the slight angle of the engine for (1) it's negligible and (2) it simplifies what shouldn't be so complicated in the first place.

If I'm in the area this weekend, I'll stop by a friend's house that I'm sure has at least one oil pan kickin around his shop.
Friends with oil pans just kickin around...
 

iamdub

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Friends with oil pans just kickin around...

Yeah, you know how us dumb, slow and trashy southerners are with our front lawns looking like a U-pull-it yard.

He's always piecing together LSs. Well, he's always blowing them apart, too. lol

His latest is a mildly built 4.8 with an LSA blower in a 'bagged '72 GMC. Took it on the Hot Rod Power Tour and blew up the transmission just a few days in.
 

HiHoeSilver

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Friends with oil pans just kickin around...

Yeah, you know how us dumb, slow and trashy southerners are with our front lawns looking like a U-pull-it yard.

He's always piecing together LSs. Well, he's always blowing them apart, too. lol

His latest is a mildly built 4.8 with an LSA blower in a 'bagged '72 GMC. Took it on the Hot Rod Power Tour and blew up the transmission just a few days in.

What I'm talkin bout!
 
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DougAMiller

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Did a little rough estimate on the oil level in the pan this evening. This is nowhere precise, just an estimate and some rough calculations. Here is a dimensioned drawing of the oil pan I found on the internet.

Oil pan.png


From this I did some rough calculations, and the red line is about where I estimate a normal 6 quarts would fill the pan to.

Oil level.jpg


And if you tilt it 10° This is about where the oil level would be.

Oil tilted.jpg


So probably 1 inch or so below the oil pump intake where the o-ring is. The problem is, now when you pour more oil in it has the full length of the oil pan to fill. By my calculations it would take an additional 3 quarts to raise the level 1 inch in this position. So my 2 quarts wasn't enough to submerge the o-ring, I needed at least one more. That or tilt it down more.
 

iamdub

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Did a little rough estimate on the oil level in the pan this evening. This is nowhere precise, just an estimate and some rough calculations. Here is a dimensioned drawing of the oil pan I found on the internet.

View attachment 229225

From this I did some rough calculations, and the red line is about where I estimate a normal 6 quarts would fill the pan to.

View attachment 229226

And if you tilt it 10° This is about where the oil level would be.

View attachment 229227

So probably 1 inch or so below the oil pump intake where the o-ring is. The problem is, now when you pour more oil in it has the full length of the oil pan to fill. By my calculations it would take an additional 3 quarts to raise the level 1 inch in this position. So my 2 quarts wasn't enough to submerge the o-ring, I needed at least one more. That or tilt it down more.

Good job! With how common this issue is, this post should be a sticky. You feel content with closure? I do! lol
 

HiHoeSilver

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Did a little rough estimate on the oil level in the pan this evening. This is nowhere precise, just an estimate and some rough calculations. Here is a dimensioned drawing of the oil pan I found on the internet.

View attachment 229225

From this I did some rough calculations, and the red line is about where I estimate a normal 6 quarts would fill the pan to.

View attachment 229226

And if you tilt it 10° This is about where the oil level would be.

View attachment 229227

So probably 1 inch or so below the oil pump intake where the o-ring is. The problem is, now when you pour more oil in it has the full length of the oil pan to fill. By my calculations it would take an additional 3 quarts to raise the level 1 inch in this position. So my 2 quarts wasn't enough to submerge the o-ring, I needed at least one more. That or tilt it down more.

You're a genius, Doug.
 

Rocket Man

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On a side note, completely off topic on the SUV’s we all love here, did anybody see the Tramontana that the police on Live PD in East Providence RI pulled over tonight? I had never heard of these cars so I looked it up. Seems there have been 8 total produced in the world. Each one is a total custom, priced over a million dollars, and only 2 were built for North American customers.

31281AB3-3511-4466-BFE3-46F92A600E7D.jpeg
 

afpj

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I thought that when the manufacturer says oil pan capacity is 6 quarts, that would mean that 6 quarts fills to the top of the oil pan? I was looking at replacing my oil pan and several makers list the oil capacity for the oil pan replacement as 6 quarts,which I assume is the capacity of the Oem pan. Just throwing it out there as this is interesting stuff. Even so, it would not change dougamiller’s estimate too far off.
 
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DougAMiller

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I thought that when the manufacturer says oil pan capacity is 6 quarts, that would mean that 6 quarts fills to the top of the oil pan? I was looking at replacing my oil pan and several makers list the oil capacity for the oil pan replacement as 6 quarts,which I assume is the capacity of the Oem pan. Just throwing it out there as this is interesting stuff. Even so, it would not change dougamiller’s estimate too far off.
Using the dimensions that I found and assuming the casting is about 1/4 inch thick, 6 quarts would fill it to approximately the line that I marked. The pan would hold significantly more filled all the way to the top, by my estimate probably over 12 quarts. The rotating assembly (crankshaft and rods) reach below the block and into the oil pan. If the oil filled it all the way to the top they would whip it into foam, something you don't want happening. So the oil level is certainly below the top of the pan.

When they describe it as a "6 quart" oil pan, they are referring to the depth of the sump. Depending on the vehicle it is intended for, some oil pans for the LS-series engines hold more or less.
 
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lowpost99

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Hey guys anyone have the o-ring part#? I recall when I did mine a few years back, there was some debate over a red vs. green o-ring with different part#'s.
 

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Yuey87

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OK, took it to a shop today to get their assessment. Even though the overfill test didn't kick the pressure back up, I am still thinking o-ring just based on the symptoms. Anyway, they say everything is fine, that it is above the minimum spec, which they state is 6 psi at 1000 rpm. That didn't sound right to me, so I looked it up. Yep, GM specs on the Vortex 5.3's are minimum oil pressure is 6 psi @ 1000, 18 psi @ 2000, and 24 psi @ 4000. So, I'm certainly above the minimums. The only time it gets close is after a cold start, right after it goes from high idle to low idle, but before the oil warms up, it will sometimes get down around 7-10 psi.

I guess as far as risking engine damage, I have sufficient pressure, it's just that it was only 2-3 months ago I don't think I ever saw it under 30 psi. Still feeling like the o-ring should be changed.
The thing about it is yes that's assuming all flow is not impaired in any way if there is any kind of buildup or restriction on flow then that pressure is not going to push that oil. Regardless of minimal spec pressure is overrated ideally you would want decent pressure and good to great oil flow. It's about balance but in this case flow is more important if you have low pressure and Ticking persist at full operating Temps and this was not doing it before oil pressure drop then you clearly have a lubrication issue. Some of these things just tick some people mistake injector noise for lifter noise there are many possibilities play it safe and put a mechanical gauge on it as mentioned before I have a 2003 mine jumps around mostly at higher RPMs after I've driven it for 30 minutes but never drops below 40 at 2500 RPMs 550 rpms its 31 psi plus, and that's in the cluster and through the PCM . I've done everything but cam retainer plate which could be a possibility and oil pump check to see if any manifold bolts have broken off you can gaze this through the fender Wells.
 

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OK, took it to a shop today to get their assessment. Even though the overfill test didn't kick the pressure back up, I am still thinking o-ring just based on the symptoms. Anyway, they say everything is fine, that it is above the minimum spec, which they state is 6 psi at 1000 rpm. That didn't sound right to me, so I looked it up. Yep, GM specs on the Vortex 5.3's are minimum oil pressure is 6 psi @ 1000, 18 psi @ 2000, and 24 psi @ 4000. So, I'm certainly above the minimums. The only time it gets close is after a cold start, right after it goes from high idle to low idle, but before the oil warms up, it will sometimes get down around 7-10 psi.

I guess as far as risking engine damage, I have sufficient pressure, it's just that it was only 2-3 months ago I don't think I ever saw it under 30 psi. Still feeling like the o-ring should be changed.
 

Yuey87

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OK, took it to a shop today to get their assessment. Even though the overfill test didn't kick the pressure back up, I am still thinking o-ring just based on the symptoms. Anyway, they say everything is fine, that it is above the minimum spec, which they state is 6 psi at 1000 rpm. That didn't sound right to me, so I looked it up. Yep, GM specs on the Vortex 5.3's are minimum oil pressure is 6 psi @ 1000, 18 psi @ 2000, and 24 psi @ 4000. So, I'm certainly above the minimums. The only time it gets close is after a cold start, right after it goes from high idle to low idle, but before the oil warms up, it will sometimes get down around 7-10 psi.

I guess as far as risking engine damage, I have sufficient pressure, it's just that it was only 2-3 months ago I don't think I ever saw it under 30 psi. Still feeling like the o-ring should be changed.

Based on careful consideration of all of the symptoms and what I have already ruled out, I'm pretty well convinced this is the o-ring. Shouldn't be any sludge, it's been fed nothing but MobilOne synthetic since new, and frequently. The shop that I had look at it didn't want to say anything was wrong since they never saw it go below spec, but I'm going to have them replace it next week. I had to get it back from them because I'm moving my daughter into her dorm this weekend and need it.

The thing about it is yes that's assuming all flow is not impaired in any way if there is any kind of buildup or restriction on flow then that pressure is not goingto push that oil. Regardless of minimal spec pressure is overrated ideally you would want decent pressure and good to great oil flow. It's about balance but in this case flow is more important if you have low pressure and Ticking persist at full operating Temps and this was not doing it before oil pressure drop then you clearly have a lubrication issue. Some of these things just tick some people mistake injector noise for lifter noise there are many possibilities play it safe and put a mechanical gauge on it as mentioned before I have a 2003 mine jumps around mostly at higher RPMs after I've driven it for 30 minutes but never drops below 40 at 2500 RPMs 550 rpms its 31 psi plus, and that's in the cluster and through thePCM . I've done everything but cam retainer plate which could be a possibility and oil pump check to see if any manifold bolts have broken off you can gaze this through the fender Wells.
 

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