A VERY THOROUGH description and a puzzling issue. You are correct about the constant pressure valve. Given all that you've done I would have to try a new CPV. It could be the source of oil pressure loss.(??)

Just out of curiosity, did you try to remove the oil pressure sensor and attach the gauge into the hole for the sensor? Any difference?

 

Yesterday I got another CPV and welded it in order to block oil flow to oil squirters. Oil pressure at idle is exactly the same, so I assume the valve was working good if we consider it should be closed below 1 bar. I'll road test it today monitoring oil pressure to see what happens. I've rebuilt many BMW engines so far but this one is giving me headaches. Thanks for the support MrMCar!

 

The worst part is that I've never seen this engine working before rebuilding it. It may have a crack somewhere, who knows...

So far:

Rod bearings clearances OK
Main bearings clearances OK
Crankshaft axial play OK
Oil Pump is new (SHOULD BE OK)
Constant pressure Valve OK (TESTED)

Next I'll be changing Oil Filter Housing...

 

Curious, where are you measuring oil pressure? AFAIK the only reliable place to measure pressure without special BMW tool is where the low oil pressure switch goes., very difficult to get to and requires the airbox to be removed.

I have heard multiple accounts of people measuring by drilling/tapping into the oil filter cap and having mixed results. There is a special tool (a modified threaded bolt for the oil filter cap) that BMW uses to measure pressure but it is hard to find and expensive.

 

Take a look, I recorded a video showing it
Oil Pressure Gauge Location:

 

I recorded some videos showing the behavior of engine oil pressure:

Oil pressure at idle, cold engine

Oil presure at idle, 80 deegres Celsius

Oil pressure revving the engine, operating temperature

Oil pressure at idle, operating temperature

 

I road tested it and oil pressure warning didn't blink even in higher oil temps at idle. Max oil temperature was 103 degrees Celsius and sometimes when lifting gas pedal rpm would go to 500 rpm, and still no oil pressure light. Mechanical gauge reads constant 0.4-0.5 bar at idle (5 - 7 psi).

 

Is it possible your mechanical gauge is not reading the correct pressure? We're only talking a difference of 3psi.

Also since this is a swapped car are you sure that the oil pressure warning light on the dash even works?

 

Is it possible your mechanical gauge is not reading the correct pressure? We're only talking a difference of 3psi.

Also since this is a swapped car are you sure that the oil pressure warning light on the dash even works?

I have two mechanical gauges and both read the same pressure. BMW also states oil pressure should reach maximum oil pressure of 4 bar (58 psi) and mechanical gauge reads almost 5 bar (72 psi).

Yeah, oil pressure warning light works fine, same way it would be in a E46.

 

I would try that oil control valve I mentioned earlier. Nothing else makes sense. Especially with good pressure with increased revs.
Dumb question: You are using 10-60 oil?

 

Yes, Castrol 10W60 TWS!

 

BTW, I just pulled a brand new oil filter housing off the shelf upstairs.
The two ports are in the same oil galley. So the gauge location is GOOD!

 

Good to know!! Thanks for checking it!

 

Interesting thread that may help diagnose your issues:

Possible Stupid Question RE: Euro Oil Cooler/Euro Filter Housing

Bimmerforums is the preferred online BMW Forum and community for BMW owners. At Bimmerforums, you will find technical how-to information maintenance specifics audio advice wheel and tire combinations and model specific details not found anywhere else. Our professionals are here to help make...

www.bimmerforums.com

the op in the thread above was seeing some drastically different pressures at the oil cap and the factory pressure switch location when oil was at operating temp. Turned out he had a clogged oil cooler. Might not help but I found the information informative.

 

Thanks eacmen,

First time I started this engine I suspected it could be a oil cooler related problem, specially because we are not using the M3 E46 oem oil cooler with this swap. We are using a transmission oil cooler from the E36. Turns out I just blocked the two hoses in order to test it, and no changes in oil pressure... The videos I posted before were recorded without oil cooler, with two hoses blocked.

 

The idle dip you showed after revving is pretty normal for these engines and can often be remedied by cleaning the ICV or doing throttle adaptations. Since you have the airbox out already might as well clean the ICV in my opinion.

Something isn't adding up. You have high pressure under load and low pressure at idle. Is your idle RPM is lower than what it should be? (should be ~800 rpm when warm)

Page 9 of this PDF outlines the oil flow throughout the engine. What is worrisome is that the pump itself should be regulating the pressure in the system so the high pressure condition should not happen. Maybe the spring for the relief valve in the oil pump is stiff from the factory but loosens up over time?

http://www.billswebspace.com/MS54B32TrainingModule.pdf

 

Yes it wouldn't happen if I had the airbox and MAF installed, just wanted to show that even with 500 rpm (way lower than idle speed) oil warning light didn't show up.
Idle speed is 800 rpm but without airbox, MAF, and ICV idle speed fluctuates between 800 and 850 rpm. With everything installed idle speed is constant 800 rpm.

It's weird that oil pressure overcomes 4 bar, it behaved the same way with the old oil pump so I don't believe the spring relief valve is stiffer in a new oil pump . Let's consider there's some dirt inside an oil gallery... At higher rpms any kind of blockage in an oil gallery would increase pressure, right? Lower flow, greater pressure. That would explain having more than 4 bar of oil pressure at higher rpms but I can't see how it would decrease pressure with lower rpms. For example, I had a problem with a M50 engine in the past. Oil pressure of that engine was 0.7 bar at idle and operating temperature (measured at oem oil sensor location) and some day it started to have loud lifter tick. Measured oil pressure again, it was 1.5 bar. Turned out some dirt blocked cylinder head oil gallery explaining why pressure was higher before the blockage.

 

With engine at operating temperature oil pressure readings are below 0.4 bar (6 psi) and BMW states the minimum oil pressure for this engine is 0.7 bar (10 psi) at idle. I'm measuring oil pressure with the gauge attached on the oil filter housing, next to the OEM oil pressure sensor location.

BMW instruction of testing oil pressure: pressure gauge attached to the oil filter cap, not at the oil pressure switch.
There could be different pressure at oil filter cap and at the sensor location. It spec at 1bar and not 0.7bar at the filter cap. You need a special drilled oil filter cap bolt for testing the pressure.

Oil pressure at idle speed with engine at operating temperature	min bar	1,0
Regulated pressure	bar	4,0

#1 Oil regulating valve, full open? Letting too much oil volume up into the vanos/cylinder head?

This is not a pressure relief valve, but it restrict the oil pressure into the VANOS high pressure oil pump. So even if this valve is bad and wide open, the VANOS pump will not consume all of this oil -- meaning the VANOS will not cause the engine oil to drop even if this valve is wide opened and therefore, it doesn't affect the engine oil pressure.

 

BMW instruction of testing oil pressure: pressure gauge attached to the oil filter cap, not at the oil pressure switch.
There could be different pressure at oil filter cap and at the sensor location. It spec at 1bar and not 0.7bar at the filter cap. You need a special drilled oil filter cap bolt for testing the pressure.

Oil pressure at idle speed with engine at operating temperature	min bar	1,0
Regulated pressure	bar	4,0

I'll get another oil filter cap and attach the mechanical gauge to it and see if there's difference. It's gonna be a great test!
Where did you get those infos? Because I have BMW ISTA+ and it shows different values

 

A few thoughts;

1) Any oil regular oil pump can only deliver X amount of oil predicated upon the size of the pump rotor/stator and the speed it's spinning at. Up to a point then we can cavitate (not the case here) if we over-speed the pump.
2) The oil is then fed into the main galley and distributed throughout the lower end. It also is sent up to the cylinder head for use by the vanos (large quantities can be called for at times) and for lubrication of the cams/followers etc.
3) Yes the BMW test plan for checking oil pressure is performed with an adapter cap on the oil filter housing, albeit the oil pressure switch (main warning to the driver) is located on the main pressure port of the oil filter housing. He is testing at the same port of the oil pressure switch. (I verified with a new housing on my shelf)

In order as to not fit an over-sized oil pump (power robbing) a balance must be struck between peak demand and be able to satisfy oiling at hot (thinner oil) idle conditions. This is where the CPV (constant pressure valve) comes into play. It's 1 bar regulated and if the oil pressure should fall below 1 bar, the spray feed for the piston cooling jets is shut off in order to ensure adequate supply for the rest of the engine.

Earlier "S" engines were bereft of Vanos. Oil was supplied to feed the cylinder head through the block into the head. Less volume of oil is needed for the camshafts etc. To this end BMW fitted one (4 cyl) or two (6 cyl) restrictors located at the top of the block, just under the cylinder head. This ensured that
A: An over abundance of oil did not depart the block.
B: there is adequate oil supply for the main galley.
I have solved two engines with premature rod/main bearing wear as during a rebuild and cleaning the restrictor(s) were left out. This condition saw too much of the oil headed into the cylinder head and partially starving the lower end during low/idle speeds.

With the advent of Vanos, which can call for large amounts of oil at times, BMW made a departure from the old way and supplied copious amounts of oil right up to the vanos. Then stepped down the pressure/volume with a regulating valve. Essentially connecting it to the main feed (again ensuring adequate supply if needed) and then stepping it down. Rather than restrict the feed. The step down happens on the other side of the vanos with the regulator fitted to the side. (The one with the locking tab on it)

I had another problem car that had bearing issues and low oil pressure at near idle/idle speed. After much frustration I cut open a large bottle (this is the lower end assembled on an engine stand) and filled it with oil. Attached it around the oil pump pick up and spun the oil pump with a drill.
The objective was to see if oil was being lost somewhere along the main caps or one of the connecting rods. (First place oil has to go.) It turned out that the builder had to grind the inside of the block slightly to allow for clearance of the connecting rods, as this motor was a 3.5L to 3.9L stroker motor.
In doing so, they ground just a little too much away on the left side of the engine and made a small hole into the main oil galley.
The oil pump was just fine, however since the oil filled the main galley, and them pushed out of the area where they ground down too much (an aneurysm if you will) the oil came up out of the sump, through the pump which was delivering the maximum (the regulator valve must have been full on?) pressure/volume, but it just left the hole and dropped back down to the sump to start it's journey over and over again. Albeit not delivering adequate volume to where it was needed.

So where does this leave Guilherme? He could try another oil pump, but I rather doubt that's his issue. Once he increases the revs, there's enough. This to me suggests a leak and/or a place where oil volume is being lost at the pump's lower end of delivery capability. Once he picks up the speed of the pump (engine speed increase) it can deliver. Keep in mind that if he is losing copious amounts of oil elsewhere in the engine, the pressure regulating valve must constantly try to overcome the increased demand.

Hence the suggestion of replacing the vanos feed side regulating valve. Either he bought it with a defective pump and the replacement is also defective? There's a loss of large amounts of oil because of large bearing clearances? (He plastigauged them) There's a hole somewhere in the oil galley? There's a large amount of oil being sent somewhere where it's not supposed to be? The two suspects here (for me) are the CPV or the vanos feed oil control valve.

Beyond that, naturally he should be checking the basics of proper oil pump gear? Restricted pick up screen? Something untoward inside the filter housing?
I don't think there's a blockage in the feed or galley. Such would see the demise of whatever was beyond the blockage, but the pressure would be more than good.

My lengthy thoughts for the day.

 

So where does this leave Guilherme? He could try another oil pump, but I rather doubt that's his issue. Once he increases the revs, there's enough. This to me suggests a leak and/or a place where oil volume is being lost at the pump's lower end of delivery capability. Once he picks up the speed of the pump (engine speed increase) it can deliver. Keep in mind that if he is losing copious amounts of oil elsewhere in the engine, the pressure regulating valve must constantly try to overcome the increased demand.

Thanks for all the support MrMCar!
I believe next steps are:
1) Measure oil pressure at oil filter cap and see if there's difference
2) Replace oil filter housing
3) Check camshaft clearances (could be a source of oil volume being lost)

Any other tests you guys suggest?

Thanks a lot guys for all the help!!

 

Engine Specs - S54 Rod Bearings - Wiki-DIY
shows much greater rod bearing clearance than you have but tighter clearance shouldn't negatively affect oil pressure.
OEM BMW S54 rod bearings are assymmetrical...I think blue ones on top of rod and red on bottom?

 

Engine Specs - S54 Rod Bearings - Wiki-DIY
shows much greater rod bearing clearance than you have but tighter clearance shouldn't negatively affect oil pressure.
OEM BMW S54 rod bearings are assymmetrical...I think blue ones on top of rod and red on bottom?

Yes. By my experience building BMW engines I found the rod bearings clearances too tight... Usually clearannces are around 0.06 mm for rod bearings and 0.05 mm for main bearings and with this one I got 0.04 mm on both. But accordingto BMW TIS this is within spec. Take a look:

Here is the video we recorded while building this specific S54. It's all in portuguese but you can see how we measured everything, the rod bearings showing red on bottom and blue on top and so on...
That day I didn't plastigage rod bearings, measured them with the dial. But the second time I opened the oil pan I plastigaged all rod bearings as well.

 

My genuine version of TIS shows the same as you.

11 41 Oil Pump with Strainer and Drive S54

Oil pressure at idle speed with engine at operating temperature	min bar	0,7
Regulated pressure	bar	4,0

 

@gscavalli Please let us know what happens after you change the filter housing. When I changed mines it actually got worse-- I went from only having low pressure on idle to having low pressure at all times. This leads me to believe my oil pump is gone but I'm not 100% certain.

 

Hi Guilherme , did you ever get to the bottom of this? I have the same issue with my 2004 E46 M3, I have a flickering red oil light when the engine dips just below idle RPM (only when at full operating temp) installed a new oil pump, pressure switch and new rod bearings (ACL) still have this problem, would love to know if you have resolved your problem

 

UPDATE:

I removed vanos, both camshafts and found two possible problems...
With camshafts out I cranked the engine until oil flows up to the cams and I noticed a lot of oil coming through a hole on rocker arm (exhaust side). There's a screw plug (picture below) on intake side rocker arm and I believe it should have the same on exhaust side? I recorded a video showing the effect of blocking that hole

Possible problem #2

I found that o-rings on the regulating valve of VANOS may be the wrong size. It seems it does not seal properly and could be a source of oil leak that could drop oil pressure

What do you guys think?

Cheers!

 

With camshafts out I cranked the engine until oil flows up to the cams and I noticed a lot of oil coming through a hole on rocker arm (exhaust side). There's a screw plug (picture below) on intake side rocker arm and I believe it should have the same on exhaust side?

You had found the root cause of the issue. Congratulations!!! Yes, only the EX rocker shaft has pressurized oil and not the IN shaft. I always wonder what is the logic for this.

Whoever holding the chain up must be a little scared of being pulled into the black hole

 

#5 screw plug

RealOEM.com - Online BMW Parts Catalog

BMW parts 3' E46 M3 Valve Timing Gear - Cam Shaft

www.realoem.com

 

I still would try to check the pressure going up at the vanos reduction valve. You have it off.

 

You are actually lucky you checked the oil pressure. Can you imagine what the exhaust camshaft, finger followers & rocker shaft would have looked like in 20,000 Kms?

 

GUYS I BELIEVE I GOT IT FIGURED OUT

I did the same test without the screw plug on intake rocker arm and guess what... There's no oil coming out of it! The screw plug goes only on exhaust side. Intake and exhaust rocker arms are completely different designs. Exhaust rocker arm supplies oil for exhaust camshaft, that's why it has some holes on it and the plug. There's oil pressure inside exhaust rocker arm. Take a look:

Intake rocker arm is only a shaft , no oil inside it, no need for a screw plug..... DAMN!
I'll reasemble evertything and let you guys know what's the oil pressure! I'm excited!!

 

Whoever rebuilt this head before had put the oil plug in the wrong shaft, and I wonder how many miles the engine ran with this mistake.

The VANOS valve o-rings look normal.

 

Wow. Amazing!! I had to watched the video twice. I wonder why bmw didnt design it to squirt oil on the intake side. I am glad you found this out.

 

Oil DOES flow into both rocker shafts. Oil feeds up through the block into the cylinder head and fills both rocker bosses.
This is how the finger followers get lubricated internally.

 

I don't think so.
I cranked the engine with both rocker shafts without the screw plug and there's no oil inside intake rocker shaft.
Finger followers get lubricated through that hole, similiar to piston pins. The difference of exhaust shaft is that it supplies oil to exhaust camshaft journals while intake camshaft journals get lubricated directly by main oil gallery.

Am I wrong?

Cheers

 

Yes, each rocker got oil lubed by gravity, not pressurized oil. But why they didn’t feed the oil to the EX cam journals like the IN side?