S52 obd1 low oil pressure confusion

[E30335i]

Long story short performed oil change on a s52 swapped e30 with mileage about 175k and noticed oil looked like how oil looks if just broke in new motor. Swapped with 20w50 gtx Castrol. Car turned on just fine, never had any issues with current ownership. Car starts up right away and oil light goes out right away. Gets driven home and then next morning went to turn it on and doesn’t want to start. It sounded like low compression but after numerous amount of tries the car finally started. Misfiring very bad and overtime it fixed itself.
Here’s the problem.
Oil pressure light flickers and goes away when tapping the gas pedal. There’s some random days where the light stays solid and light goes off at 1500rpm.
Here’s what we did to check.
It has a z3m oil filter housing so extra plug for the pressure gauge. It was reading inaccurate but if the light goes off at 7.5psi and at 1500rpm it turns off definitely an issue. We take off the pressure gauge to look inside and there’s barely any oil flowing up the the gauge. We then added oil into the housing through the port to see if that helps at all. Inconclusive.
After leaving it running at 1500rpm once the car gets to 1/4 temp, oil pressure sky rockets to within spec. we let off the throttle and had a working gauge and was at 14psi at idle.
So at cold it’s very low and once it warms up it’s normal. Right now I have the oil pan off and the oil pump nut was not loosened and the oil pick up tube is free from debris. Any ideas? Next step was to pressurize the system with a tube going into the oil pump with oil and then next take the oil pump chain off and spin the nut and see if oil circulates. I never had an issue with 20w50. It’s in 5 s52 cars at the moment.


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[flyfishvt]

Test it with 10/40. Sounds like the oil is thinning out when it gets warm

Do a compression test and a leak down test.

Send a oil sample to Blackstone to be tested.

[bluptgm3]

Factory fill was 5W-30, at 284k miles I’m running (Amazon Basics) 5W-40 API SN/SM or SL, ACEA A3/B4, with occasional lifter chatter on cold start.

I’m guessing you are running oil that is too thick in order to mask a bearing clearance issue.

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[Eric93se]

50w oil is only for the track or 110F desert weather.

[blckstrm]

Long story short performed oil change on a s52 swapped e30 with mileage about 175k and noticed oil looked like how oil looks if just broke in new motor. Swapped with 20w50 gtx Castrol. Car turned on just fine, never had any issues with current ownership. Car starts up right away and oil light goes out right away. Gets driven home and then next morning went to turn it on and doesn’t want to start. It sounded like low compression but after numerous amount of tries the car finally started. Misfiring very bad and overtime it fixed itself.
Here’s the problem.
Oil pressure light flickers and goes away when tapping the gas pedal. There’s some random days where the light stays solid and light goes off at 1500rpm.
Here’s what we did to check.
It has a z3m oil filter housing so extra plug for the pressure gauge. It was reading inaccurate but if the light goes off at 7.5psi and at 1500rpm it turns off definitely an issue. We take off the pressure gauge to look inside and there’s barely any oil flowing up the the gauge. We then added oil into the housing through the port to see if that helps at all. Inconclusive.
After leaving it running at 1500rpm once the car gets to 1/4 temp, oil pressure sky rockets to within spec. we let off the throttle and had a working gauge and was at 14psi at idle.
So at cold it’s very low and once it warms up it’s normal. Right now I have the oil pan off and the oil pump nut was not loosened and the oil pick up tube is free from debris. Any ideas? Next step was to pressurize the system with a tube going into the oil pump with oil and then next take the oil pump chain off and spin the nut and see if oil circulates. I never had an issue with 20w50. It’s in 5 s52 cars at the moment.


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I've got my flame suit on. Try using some Seafoam.

I'm not kidding. I just went through this with my Escalade at 213k miles, though my problem was the opposite - it had great pressure at first startup, would slowly drop over about 30 minutes until it got to 10 psi and the car would freak out. I added an extra quart over full to do some diagnosis and that got me nowhere.

My oil samples are sitting on my table, will go out to Blackstone tomorrow.

Conventional wisdom was that it was the oil pickup o-ring, or that the cam bearings were shot. I get a Blackstone report every oil change, so I didn't feel like the bearings were bad - especially since this just up and happened one day.

First I tried the oil pressure sensor, then the screen for it - no dice.

I opened it up - I dropped the front diff and the oil pan and did the o-ring - and I knew when I took it off that it wasn't the problem. The pan was super clean - no sludge at all, nothing in the pickup screen. I buttoned it back up, and now the problem took only 90 seconds to go from 45 psi to 10 psi. Over that 90 seconds it went from 1 quart over full to 2 quarts low.

At 90 seconds it was clearly not a "hot oil" issue.

I went to bed defeated - who wants to go to bed at 2:00 am having failed miserably?

I got up the next morning and all that oil was back. It was getting trapped somewhere up top despite the fact the LS3 has ginormous return channels and what seemed to be happening was theoretically impossible.

So, it wasn't consuming oil and it wasn't any conventional problem. At that point I figured a hail Mary was worth $20.

I dropped a full quart of Seafoam into the oil and ran it 90 seconds until it got down to 10 psi, then came back 20 minutes later and did it twice more. It looked like it was 2 quarts low still at that point (after the 3rd run).

I came back an hour later and it took about 10 - 15 minutes to get down to 10 psi. The oil no longer read low after a run, and I could restart it 5-10 minutes later and run another 15-20 minutes. Did that 3 times again.

I came back another 2 hours later and repeated the process (except it took longer). By the third run it was maintaining 15 psi.

I came back an hour later and it held 20 psi once it came up to temperature.

I ran it gently for two days and changed it and it's been fine. No one can tell me what happened, but it's fine. I still keep it on the oil pressure readout full time, but it behaves completely normal.

Long story short - something clogged the oil return in my motor. Before doing a full rebuild (I just had the heads off 2 years ago), I decided to try a solvent and see if it would dissolve whatever was plugging the oil system, and it worked miraculously.

I'm not a hack - I've done both the head on my M3 and both heads on the LS3 in my Escalade. And just about everything else on my M3 a person could do.

This problem defied the normal diagnoses (there are pages of discussion with machine shops and old small block builders I didn't include here), and at the end of the day $20 of Seafoam and a little patience completely fixed my issue.

Or put another way, it isn't going to make it worse, but it just might save you days of work.

[E30335i]

I’m in a lot warmer climate that the coldest is 48F average. This car is set up for track. I’m pretty sure the oil is fine because we have people using 10w60 for their daily. I also used to daily 20w50 in my e30 s52 but I think oil weight is a political subject so let’s stay away from that, but for this particular case If I can’t find a issue gonna put 5w40 in the oil. It’s just weird how it’s the opposite of lack of oil pressure until it comes to temp and I might also add when it’s warm the oil goes down significantly. I never witnessed a car go down that dramatically.


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[blckstrm]

Seriously - it sounds like you have a blockage somewhere. A solvent like Seafoam or Berryman's could be a very simple solution to break up whatever seems to be clogging the system. I certainly wish I'd tried that before dropping my front diff and oil pan.

[gdavid]

I know very little of e30 engine swaps but is it possible that your oil level is just lower than you think it is due to the angle of the engine? This swap requires a e34 oil pan if I recall correctly which is installed at a 30 degree angle just like the e36, with the engine at 20 degrees in a e30 and the dipstick measuring at the lowest point of the pan, perhaps you need more oil in it. I could very easily be wrong and I'm sure this is all thoroughly covered in the e30 realm.

[E30335i]

You guys wouldn’t believe it, clogged oil filter. Pumped up oil from pick up tube to the pump with oil not coming out of the oil pressure sensor. Removed oil filter housing to verify oil movement. Passed. Put everything back together, turned on without oil filter and bam. New oem filter. Bam. Performed oil flush with existing oil and quart of atf for 30 min. New oil change with oem filter. Car is smoother than ever.


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