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7 Series - E65 / E66 (2002 - 2008)
Discussion of BMW's 4th generation E65/E66 7 Series flagship. The E65 generated much controversy, due to its radical styling and iDrive user difficulties. Nonetheless, the E65 broke records to become the best-selling 7-series iteration ever, especially after its 2005 facelift.

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  #1  
Old 09-03-2018, 05:58 PM
HerbP HerbP is offline
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Random Oil Pressure Light

Oil Pressure light
I have been chasing a ghost to find out why I am getting random low oil pressure warnings, after replacing my valve cover & timing cover gaskets. I have pulled the valve covers again to make sure nothing was left in the topside of the heads after replacing my gaskets. I found nothing out of the norm.

I changed all 6 of my check valves, &bblown out everything possible including where the oil pressure switch is installed. This weekend I also swapped the Vanos solenoids out of my 750, & that has not really helped either. Since installing a oil pressure gauge I have not gotten the light, but the oil pressure seems to be a bit low to me.

At idle cold I am getting 40 psi.
Oil pressure at operating temp I am getting 22 psi.
While driving at 1500 rpm's I am getting 22 psi.

The oil pressure seems to be a little higher after changing the Vanos solenoids, but not where I feel it should be. There is not a diagnostic setting in ISTA, that will read oil pressure on my car. Other models have that ability. I have also upped the oil to 10w40 to see if that would help, but that did not work either. Without having oil pressure readings before the low oil pressure warning started, I do not have a baseline to start with. I know that the Vanos system controls the oil pressure inside of the engine, & I don't know why my problem started after the valve cover gasket replacements. If anyone has any documented readings at set temps & RPM's, this would help me determine if I really have a problem now. I don't want to trash my engine, but I can not seem to find anything that might help me solve my problem. I do not feel this is an oil pump problem, but I really don't want to waste 600.00 for a new oil pump, until I am positive it might be the problem. I have read a lot of threads from different forums with others having the same problem, that really points me in the right direction. My next move is probably inspecting the cam ledger bearings to see if there is a problem there, & possibly removing the Vanos units why the valve covers are off. If I have to remove the camshafts, I will probably drop the engine to go ahead & change my valve seals & clean the Secondary Air system while I have easy access to everything.

Any help would be much appreciated!
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  #2  
Old 09-04-2018, 12:30 PM
JCMech JCMech is online now
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Are you seeing a message on the instrument panel or control display saying low pressure?
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Old 09-04-2018, 01:43 PM
HerbP HerbP is offline
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On the Idrive.
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  #4  
Old 09-04-2018, 02:25 PM
JCMech JCMech is online now
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Great. It might be something minor. If it was a light on an actual oil pressure gauge you added then its probably something you need to dive deeper. The idrive is reporting on the oil pressure sensor below the vacuum pump, which is a switch. It does not measure pressure , just if there is pressure or not. The oil pressure message will appear if pressure is below 7 psi. It might be a bad switch or plug. If your low oi pressure warning happens every few minutes, I would suggest unplugging the sensor. IF its a bad sensor, your message will no more reappear. IF the message still appears, it is a bad plug or wire.
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Old 09-04-2018, 02:43 PM
JCMech JCMech is online now
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Or just swap the pressure switch from your 645 and 750 and see if the issue travels
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Old 09-05-2018, 06:32 PM
HerbP HerbP is offline
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Quote:
Originally Posted by JCMech View Post
Or just swap the pressure switch from your 645 and 750 and see if the issue travels
I have installed a new sensor without any difference. I was hoping that one of my solenoids might be a problem since one fell off my work bench, but the ones out of the 750 made no difference. It would be nice to know how & what path the oil pressure takes. If the Vanos system is controlling the oil pressure & the oil pressure to the sensor is all that is required, how do you really determine if you really have a problem. The oil leaving the pump is somewhere around 65 psi, with the the Vanos system using what it needs to operate. What oil pressure is required at the bearings & the crankshaft? I am considering order some more fittings to add to my 750 to use as a baseline. This will probably tell me what is normal for our engines. If I find a difference in the oil pressure readings, where do I start to look?
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Old 09-06-2018, 07:27 AM
JCMech JCMech is online now
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Does your oil pressure gauge show anything lower than 5 psi? The switch has the on/off psi stamped on it. Mine is 0.3 bar or 4.4 psi.

Idle from cold , mine is between 30-40psi.

Here's the specs-

Min (14.5 psi) and max (58-116 psi) oil pressure at 20C

What's important too is that it delivers 9-12 L/min at 700rpm and 50-55 at 6500rpm
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Old 09-06-2018, 07:39 PM
HerbP HerbP is offline
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Quote:
Originally Posted by JCMech View Post
Does your oil pressure gauge show anything lower than 5 psi? The switch has the on/off psi stamped on it. Mine is 0.3 bar or 4.4 psi.

Idle from cold , mine is between 30-40psi.

Here's the specs-

Min (14.5 psi) and max (58-116 psi) oil pressure at 20C

What's important too is that it delivers 9-12 L/min at 700rpm and 50-55 at 6500rpm
At cold idle I have 40 psi at 90 F, & 22 psi at 235 F. I have no clue on the volume that the pump is delivering. I am not seeing the increase of pressure as I am increasing the RPM's, that is what really concerns me. I replaced my cooling fan today as it went up in smoke, & maybe it has something to do my problem. I have considered try to put the oil pressure gauge at the filter, to see what kind of readings I am getting there. That might be a higher pressure eliminating the Vanos system regulating the oil pressure the oil pressure switch sees?
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  #9  
Old 09-07-2018, 10:37 AM
JCMech JCMech is online now
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The oil pump is pretty robust unless the pressure relief or control valves in it are shot, which is highly unlikely. I do not think it is an issue. And there is definitely going to be a higher oil pressure at the filter. See the diagram I've attached.

Can you answer my question on whether you see oil pressure lower than 5-7 psi on you oil pressure gauge at any time? Cold start, warm up , then go for a drive. This will confirm whether it is really an oil pressure problem or something else.

Of the 6 check valves , the lower most check valve goes to the chain tensioner. The upper two, goes to the vanos solenoids controlling the exhaust and intake cam timing.


Here's a diagram of the oil flow from the N73 which is basically identical the the N62 except for 4 more cylinders.
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Old 09-07-2018, 07:21 PM
HerbP HerbP is offline
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Quote:
Originally Posted by JCMech View Post
The oil pump is pretty robust unless the pressure relief or control valves in it are shot, which is highly unlikely. I do not think it is an issue. And there is definitely going to be a higher oil pressure at the filter. See the diagram I've attached.

Can you answer my question on whether you see oil pressure lower than 5-7 psi on you oil pressure gauge at any time? Cold start, warm up , then go for a drive. This will confirm whether it is really an oil pressure problem or something else.

Of the 6 check valves , the lower most check valve goes to the chain tensioner. The upper two, goes to the vanos solenoids controlling the exhaust and intake cam timing.


Here's a diagram of the oil flow from the N73 which is basically identical the the N62 except for 4 more cylinders.
I have not seen 7 psi on the gauge since all of this started, but the lowest when the engine ran hot was 12 psi. This was when my cooling fan quit, & I was forced to pull over to cool the engine down. The normal pressure at 240 is around 22 psi. I have replaced all 4 solenoids & all 6 non-return valves. I have learned that if the Vanos solenoids are not seated all of the way, it will cause all kinds of timing errors.
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  #11  
Old 09-08-2018, 12:37 PM
JCMech JCMech is online now
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Quote:
Originally Posted by HerbP View Post
I have not seen 7 psi on the gauge since all of this started, but the lowest when the engine ran hot was 12 psi.
Logically this rules out the switch. The idrive should not display the low oil pressure message since the DME never sees anything less than 5-7 PSI. Perhaps you have a loose connector in the plug.

Yes, experienced that too. When the solenoid is not in all the way, the solenoid will not get the proper oil pressure to rotate the vanos, thus causing timing problems. You can get similar issues if the screen is stuck with gunk too. Clean engine, happy engine.
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Old 09-08-2018, 07:37 PM
HerbP HerbP is offline
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I wish I would have test fitted the solenoids in the heads while I had the timing cover off, just to see how tight of fit that here actually is. It is a very good possibility that I did not seat the solenoids all of the way causing the problem. After I went back in & inspected all of my work & found nothing wrong, I have not had any more low oil pressure warnings. I have also found some brittle wiring leading up to the solenoids. I would have probably never worried about any oil pressure readings, until I saw what they were at idle. My small blocks never ran pressure this low.
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  #13  
Old 09-10-2018, 11:46 AM
JCMech JCMech is online now
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Glad to know the problem is behind you. It would be nice to know what exactly caused it though.
12 PSI does seem low as the min specs is 14.5 If you have a change to drop the oil pan, take a look at the screen inside the oil pickup. Highly unlikely, but possible it is partially blocked.
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  #14  
Old 09-10-2018, 07:33 PM
HerbP HerbP is offline
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I will have the permanent oil pressure sensor installed tomorrow where I can watch it inside the car. It will have a set point to catch my attention. I also have a coolant temp gauge that I will be installing this week to. No more idiot lights for me. I have also got to rerun all of my Vanos solenoid wires, since the heat has toasted them & they are just breaking off. I am picking up the wiring connectors from the local dealer tomorrow, then I will pull the new wires up into the black boxes on top of the intake.

I will also install the fittings on my 750 for oil pressure readings at certain temps & RPM ranges. This will give me a good baseline & comparison for both cars in my area. I will post the readings to hopefully help someone else in need. I hope the readings for both engines are close where I can put this problem to rest!
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