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Discussion Starter #1
I have made some bad decisions in my time, but I think my choice of mechanic has taken the top spot for worst decision so far.
A series of bad choices on my part led me to let an incompetent mechanic change the engine in my 320Ci, and after getting the engine changed I have an issue that is frustrating the life out of me.
My oil pressure light comes on once the car is up to temperature. Towards the beginning it disappears as soon as I touch the accelerator, but as the heat builds, the light stays on until gradually higher RPMs up until around 1500 RPM.
The mechanic who changed the engine, and who’s responsibility this engine now is, says it’s probably something stupid and I shouldn’t worry about it. I strongly disagree however I can’t see him until Monday. An indie BMW specialist who I consulted over the phone thinks it may be the vanos seals, but cannot work on my car until deep into December. A few other people think it may be a variety of other things, but I don’t know who to listen to because I need to get my car fixed ASAP and due to covid I cannot afford to let mechanics blindly chase this issue.

Has anybody experienced the same issue as I have? What did it turn out to be?
Thanks in advance!
 

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Answer to your title is yes. Oil pressure is responsible for moving vanos pistons and adjusting cam timing. Oil is fed to the vanos via the vanos oil line that is attached to the rear of the oil filter housing. If you have insufficient oil getting to the vanos solenoids you don't get the required travel of the vanos solenoids and thus the vanos pistons don't move and adjust the camshaft angles. Solenoids can get gummed up too. Vanos piston seals can go hard and allow oil to leak past rather than move the pistons. The correct level of clean oil is an important part of vanos function.

But I don't see how any of this will cause your oil pressure light to come on. I presume, btw, that the light you are referring to is RED not AMBER. An AMBER oil light means that your oil is low and needs topping up. If it comes on with the correct oil level and stays on for about 10 seconds and then goes off you need to replace the oil level sensor in the bottom of the oil pan. If the light is RED with the correct level of oil, and you are getting oil to the head, I would change the oil pressure sensor which should be in at the rear of the oil filter housing before doing anything else.

There is a possibility that the nut has come loose, or even come off, the oil pump shaft. That's the worst case scenario. But you would hear a lot of rattling from the timing chain if that were the case.
 

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Discussion Starter #3
Thanks for the reply, Bopper. It is a red light, and the oil pressure switch has recently been changed (weeks ago) with an OEM part from BMW. My oil is filled the the correct level and I cannot hear any strange noises coming from the engine while at idle or cold.
However, the day after I got the car back, I took it on a 10 mile drive just to double check that another issue I had had gone away for good, the engine sounded different once it was up to temperature. It seemed much louder and rougher. I stopped for a few minutes and the noise went away as I was on my way home.
 

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Thanks for the reply, Bopper. It is a red light, and the oil pressure switch has recently been changed (weeks ago) with an OEM part from BMW. My oil is filled the the correct level and I cannot hear any strange noises coming from the engine while at idle or cold.
However, the day after I got the car back, I took it on a 10 mile drive just to double check that another issue I had had gone away for good, the engine sounded different once it was up to temperature. It seemed much louder and rougher. I stopped for a few minutes and the noise went away as I was on my way home.
Is oil getting to the head? Run the engine for a bit. Turn it off and remove the oil filler cap and see if the cylinder head is wet with oil. Obviously it should be. But read this entire thread. There are some potential solutions. Particularly the references to crankcase pressure and CCV. See what you think.

 

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Changed the engine......

I did see one time a very odd issue caused by mixing up the Banjo bolts of the P/S and the vanos line.
Year/model dependent, some have a restrictor/flow check valve
 

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Discussion Starter #7
My idle seems to be 550-650 when warm, sometimes it drops under 500 for a second though.
However, can this be causing my oil pressure light to illuminate even at 1000-1500 rpm?
 

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My idle seems to be 550-650 when warm, sometimes it drops under 500 for a second though.
However, can this be causing my oil pressure light to illuminate even at 1000-1500 rpm?
Your idle is much too low, and yes, that can be a cause. The idle is too low in any case, and you should find out why.

I would replace the VANOS seals and clean your ICV.

Then I would methodically check fuel pressure then do a smoke test.
 

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My idle seems to be 550-650 when warm, sometimes it drops under 500 for a second though.
However, can this be causing my oil pressure light to illuminate even at 1000-1500 rpm?
Red oil light on at 1000 rpm - 1500 rpm sounds like a serious problem, especially with a unknown or rebuilt engine. Plus the mysterious engine noise you said, I think you need to be serious.

I don't think VANOS seals -- old or new -- are bad enough to cause low oil pressure this bad (a really bad leaky VANOS seal that caused the red oil light should had caused an error code issued because the cam was not advanced/retarded on time, but this is not the case). So forget about VANOS seals is the root cause.

You have either bad oil pump, clogged oil holes with gasket compound used in the rebuild, or oil pressure regulator was wrong part or installed wrong, or rag or paper town left in the oil filter housing, etc.
 
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