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Discussion Starter #1 (Edited)
Alright, I know what you're thinking," a newby who hasn't read through the threads on the oil pressure sensor/switch!"

Yes I have read and yes I have used the advanced search to find threads, but no matter how many keywords I use I still end up with dozens of pages.

I've got a "cold start" oil light that stays on for about 5-6 seconds every time I leave the car parked for a couple of hours or more . Upon start up (when the light is on) it sounds as if I have done an oil change then when the light turns off there is an audible change in engine note. (just as after an oil change)

I think it fair to assume that the filter housing is emptying back into the sump, the question is what is giving way? I've done a considerable amount of searching on the issue and have found one thread (can't bloody find the thread again for reference for the life of me!!) that mentioned the one way valve that sits in the housing. It seems that this one way valve does have a tendency to deform.

Can anyone confirm this, heard of this problem and/or can give me any suggestions?
 

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Is it a red oil light or a yellow oil light? If it's yellow, replace your oil level sensor. If yours is original, it's probably the issue. It's like a $60 part for the OEM version (Hella).

If it's red, that's not good.
 

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I have the exact same issue with my 03 330i. The red Oil light stays on a few seconds longer than I'm comfortable with at start up. Just like the OP I can hear a difference in the sound of the motor once the light goes off. It sounds like valve tap which quiets down immediately after oil pressure has built up in the lifters. It just takes a little longer than it should. I don't have any CEL or oil light while running. It appears to be just a start up issue. The car has 142k miles, fresh oil at correct level. Symptoms are similar whether it's a cold start or warm start.

I did notice that my plastic oil filter housing cap was missing one of the small green o-rings at the tip. I didn't have replacements at the time I was doing my oil change but they are on my To Do list.

OP, As a cheap and easy 1st step, I'd suggest you start by checking your oil cap and replacing the 2 o-rings. Search for thread title "project M54 engine: oil filter housing" for a good pic explaining the rings I'm referring to.

Good luck!
 

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Discussion Starter #5 (Edited)
Thanks 325ragtop. I've seen the thread you mentioned and it mentions the valve once (he couldn't get it off) but I saw another (I didn't bookmark the page don't know what site, aaaaarrrggg!) that mentioned the deformation of that non return valve on several housings...the guy seemed to be a mechanic and had several go through his hands.

I got the little orings and a bmw original filter for my next oil change but I've read, from someone who has the same problem and tried replacing the two, that it makes no difference. I've had this problem for well over half a year now and have just gotten around to getting the space organized to finally try to knock this one on the head come December, as well as other things, but it would be nice to have some sort of confirmation of my hunches before I put the car up on stands and take the bugger apart. I was thinking of cleaning the housing out with gas and seeing if it holds gas or leaks from the valve. Housing is ***8364;250 from the stealers, the valve does not sell separately and they'll need to special order so once I've ordered I have to buy....if that's not the problem I'll have to get someone else involved and take off the sump and investigate the pump.

That's my plan, so far, Stan.
 

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I believe there is a check valve located in the oil filter housing that can fail. This results in all of the oil in the filter draining back into the pan and caused longer than usual priming.
 

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That should be easy to check. Just pull the filter after the car sits overnight and see if the filter canister is empty. Old M30 big 6 cylinders had this problem. The fix was a new filter housing.
 

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Discussion Starter #8 (Edited)
That should be easy to check. Just pull the filter after the car sits overnight and see if the filter canister is empty. Old M30 big 6 cylinders had this problem. The fix was a new filter housing.
Thanks bmwbob89,

Unfortunately, if you take the cap off it automatically drains into the sump...that's part of the reason why the cap has the 2 small o-rings at the tip.

I'm coming to the conclusion that replacing the housing might be inevitable.
 

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Hey Beav, It takes some time for it to drain out. Especially if the oil is cold and pretty thick. Loosen the cap and pull it right up. There should be a lot of oil in there. If not it has drained back.
 

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Discussion Starter #10
Hey Beav, It takes some time for it to drain out. Especially if the oil is cold and pretty thick. Loosen the cap and pull it right up. There should be a lot of oil in there. If not it has drained back.
Alrighty then, confirmed!! The other day I gave it a go, to check if the filter was well seated (aftermarket MANN filter) and the housing was empty with no real sign of "recent" drainage.

Cheers mate!
 

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Discussion Starter #11
Have any of you guys given the engine flush treatment a go? (you know, the "can" that you throw in the oil sump one hour before you give it a change to clean out the gunk.) I've been suggested it several times but am seriously hesitant, don't need it to take away all the "good" gunk and give me more problems....my mechanic gives me the 50/50 when I ask him is it a good thing or a bad thing. (good for him, bad for me?!) hahahaha
 

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Hey Beav, It takes some time for it to drain out. Especially if the oil is cold and pretty thick. Loosen the cap and pull it right up. There should be a lot of oil in there. If not it has drained back.
bmwbob89 is right…. that's a good test and I just did that myself earlier today. I have 2 E46's… my 325 which had no oil pressure issues and is not missing it's o-rings was about 2/3 full of oil when I pulled the cap to take a lot. My 330 was bone dry. I swapped caps, and sure enough, the problem followed the cap! I picked up a couple o-rings and my problem is solved.

Stan, your case may be different, it sounds like you are confident your o-rings are correct and intact. You may be right about needing a new oil filter housing. Sounds like you're on the right track. Good luck!
 

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Discussion Starter #13
bmwbob89 is right…. that's a good test and I just did that myself earlier today. I have 2 E46's… my 325 which had no oil pressure issues and is not missing it's o-rings was about 2/3 full of oil when I pulled the cap to take a lot. My 330 was bone dry. I swapped caps, and sure enough, the problem followed the cap! I picked up a couple o-rings and my problem is solved.

Stan, your case may be different, it sounds like you are confident your o-rings are correct and intact. You may be right about needing a new oil filter housing. Sounds like you're on the right track. Good luck!
They looked in good order but ..... you're right, it must be done to make sure. The last time I had a chance to take it off I had forgotten the o-rings(...mental note "O-rings must be done!") .

Do you remember the socket size?...36 mm was it?
 

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I've used motor flush in many of my cars over the years (and I've owned over 40 cars) I can't say it's ever made a huge night & day difference, but i've never known it to cause any harm and I think it's good preventative maintenance. I tend to buy cars with >100K miles and often with unknown maintenance history. My typical regimen is to do an oil change immediately, regardless of what the prev owner says about when it was last changed. I'll put a can of flush in it before that oil change. I will then run a shortened interval of +/- 1K miles, and do another flush/oil change. Then I'll run another 1K-2K miles and do a 3rd oil change (no flush) before resuming a normal oil change intervals.

BTW, The stuff I use says to put it in a cold motor, let it run at idle for 5-7 mins and then drain. I follow those instructions. I don't think pouring it in any sooner an just letting it sit will do any harm, but doubt it would help, and I definitely would not run the motor under any load or for longer than 10 mins.
 

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No idea about the size***8230; big adjustable wrench works well for me***8230; no need to go crazy torquing it down, that's not how it seals. It should be fully seated and just over snug.
 

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Discussion Starter #17 (Edited)
(Engine model M47 (?), 2.0L diesel 130+ horsepower)

Had a chat with the "Stealers" today and got absolutely nowhere as they gave me no access to mechanics (why would they save me money when they can make it?!...such is life) Gave the orings a change a couple weeks ago with no results, so I guess I'll have to give it a go myself (grab some balls), save myself the 160***8364; in labour (+ 21% tax, not including diagnostics, and whatever else they want to add on....) and take it apart the filter housing myself (mental note: "grab some balls, man!"). Got myself an online manual to study but it's slow as stink as well as horribly cumbersome. (Should I drain the cooling system?)

Will avoid the engine flush as I'm committing to dismantling the filter housing anyways (don't "fix what is not broken"), got my "garage" (carport) space sorted for about a week and will be doing an oil change (needed, 20,000 kms) anyways.....jack stands for a week.

I've got 2 theories (before diving into the "deep end")

1. the oil filter isn't properly seated (or.... cap failure??). As mentioned before, I have an aftermarket (MANN) filter installed, and have noticed that it doesn't stay attached to the cap unit. The one I removed from my last oil change before was slightly squashed and twisted therefore was improperly fitted. I don't know if this could be a factor but would like some outside advice. Now have an original BMW filter to install and will be somehow filling the removed part (filter housing) with diesel to try to see if or where the part is leaking from (easier said then done).

2. (My conclusion through months of searching on the web) I have a one way valve failure in the housing where it drains into the sump, slowly but surely, and leaves the housing devoid of oil, therefore takes the 5 seconds to fill and pressurize. It's an "educated" guess (lacking input) but I've committed to the deduction.....the way I look at it, I'm saving myself 200***8364; +/- in labour charges by giving it a go myself, therefore I'm able to invest into a chip tuning! (the silver lining!) :)


I have a secondary problem, which is just as minor but would love some insight just in case I'm "overlooking" a serviceable part . While the turbo is in its power band (2000 rpm +/-) and I let off there's a small but "noticeable" lag and surge when stepping back on the accelerator. It's far from serious but I've cleaned the MAF with contact cleaner and have even scrubbed the intake manifold bone clean from carbon after cleaning the EGR(MAF was cleaned in the process and had a tiny bit of carbon crudding it up) ...i'm now thinking there's a piece of the turbo that I've "overlooked"?

Un saludo, ANY insight is greatly appreciated and... thanks for reading! (....and hopefully replying!)
 
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