Common places for an oil leak?

My 2004 330Ci vert has 94k on the clock and has had plenty of maintenance according to the records. It has a small oil leak, yet I see that the rocker cover gasket was replaced a year ago at 77k due to a leak. I have not found where the leak is coming from yet, so I wanted to ask where is the most likely culprit considering the aforementioned?

Originally Posted by VECTOR

My 2004 330Ci vert has 94k on the clock and has had plenty of maintenance according to the records. It has a small oil leak, yet I see that the rocker cover gasket was replaced a year ago at 77k due to a leak. I have not found where the leak is coming from yet, so I wanted to ask where is the most likely culprit considering the aforementioned?

Oil filter housing gasket is probably your problem, very hard to detect unless you have a lift, my money is on this. And BTW, it's only cost you about 8 dollars for the gasket, and about two hours of your time.

However, I would recommend to replace the CCV system and it's associated hoses if not done recently, why? Because it also could be the culprit of your slow leak and while doing the oil filter housing gasket you have tons of room to do the CCV.

I am new to BMW's, so I am not sure what a CCV system is, and why it should be changed if the leak is found elesewhere?

add the oil pan gasket to the list. As for why these parts need to be changed, basically all rubber gaskets and hoses degrade over time..

I think I've replaced 4 of the various gaskets and seals by now, at 165K. From what my mechanics tell me, the main oil pan gasket is usually the last to go. It seems they all went about 120-140 K.

Originally Posted by Miko_10

add the oil pan gasket to the list. As for why these parts need to be changed, basically all rubber gaskets and hoses degrade over time..

Nah! Don't need to replace oil pan gasket unless it's obvious.

Originally Posted by VECTOR

I am new to BMW's, so I am not sure what a CCV system is, and why it should be changed if the leak is found elesewhere?

Search for CCV and you will learn a great deal.

CCV=PCV=oil seperator

You know you can live with leaks of a small sort for quite a while...that's number one.

Two--reason to do ccv while doing oil filter housing is that it's a system that fails at some point and it's pretty convenient to do while at ofh.

But, another thing you could consider is planning both of these things leisurely...study the diys...etc...and then after you've got all the parts, something else will necessitate your going in there anyway...and you can take care of it all in a brutal weekend event!

Also, I'd add the vanos oil line to the list for leak sites too...easy to get to when ofh is off...four crush washers needed.

Anyway, if the cooling system gives you issues...a good time to get into that coz you need to and while everything is out...move on.

An oil leak isn't good...but if monitoring oil levels at same time of day...like in a.m. should be easy to see if rate of loss increases substantially and move up the schedule for repair.

Also...take off underplate and clean it...so easier to monitor things...while you're there...might spray off bottom of engine a bit...might make it easier to spot leak.

While you're underneath looking up with good flashlight, look for leaks in the lines coming off the PS reservoir...gasket leaks in cap (very well hidden gasket...new part $2...buy it)...put real screw clamps on hoses underneath if the leak is from there...very common.

Other oil leaking sites? Ah, PS hoses leak from front lines too...all metal end and fitting next to radiator...and if you're an automatic, then I think trans has a line to cooler somewhere also...fluids that can leak too.

Crib notes on ofh...just did it...drop PS pump from Alt and let it sit, remove alt, remove ofh and mark locations of bolts (different lengths)...

HTH

Doug

Originally Posted by dmax

CCV=PCV=oil seperator

You know you can live with leaks of a small sort for quite a while...that's number one.

Two--reason to do ccv while doing oil filter housing is that it's a system that fails at some point and it's pretty convenient to do while at ofh.

But, another thing you could consider is planning both of these things leisurely...study the diys...etc...and then after you've got all the parts, something else will necessitate your going in there anyway...and you can take care of it all in a brutal weekend event!

Also, I'd add the vanos oil line to the list for leak sites too...easy to get to when ofh is off...four crush washers needed.

Anyway, if the cooling system gives you issues...a good time to get into that coz you need to and while everything is out...move on.

An oil leak isn't good...but if monitoring oil levels at same time of day...like in a.m. should be easy to see if rate of loss increases substantially and move up the schedule for repair.

Also...take off underplate and clean it...so easier to monitor things...while you're there...might spray off bottom of engine a bit...might make it easier to spot leak.

While you're underneath looking up with good flashlight, look for leaks in the lines coming off the PS reservoir...gasket leaks in cap (very well hidden gasket...new part $2...buy it)...put real screw clamps on hoses underneath if the leak is from there...very common.

Other oil leaking sites? Ah, PS hoses leak from front lines too...all metal end and fitting next to radiator...and if you're an automatic, then I think trans has a line to cooler somewhere also...fluids that can leak too.

Crib notes on ofh...just did it...drop PS pump from Alt and let it sit, remove alt, remove ofh and mark locations of bolts (different lengths)...

HTH

Doug

nice info, and based on the thread i made about my leak and input from other fanatics, the oil filter housing gasket seems most common, i will also be tackling that something this week

Originally Posted by joneperry

nice info, and based on the thread i made about my leak and input from other fanatics, the oil filter housing gasket seems most common, i will also be tackling that something this week

Thanks, JP...

Don't forget #1 though...a tiny leak is just that...it doesn't mean you're a bad person or anything to leave it be...to ignore it and not monitor...then you're bad!

If you've read any number of posts...nothing personal...and just saying...but something will happen that will necessitate your getting it up in the air, removing fan and belts...maybe airbox...at that point...remove PS pump, alt, ofh gasket...then make right turn and replace elbow and have to at that point remove TB, clean ICV, DISA...new gasket/o-ring/grommet as appropriate. CCV right there.

I did all this...with radiator and heater hose replacements...think maybe 15 hours work total over 2.5 days...not horrible and very redeeming.

Got 33+ mpg on trip from NNJ to DC...at times 35. Also, since ICV mostly I think...have prolly gained from my 21 ish mpg/city to 23 or so.

Might some of this be due to the ofh gasket...doubt it, but could be...anyway, lots to do down there...doable diy...don't know if you were doing this or not...

Finally, burning oil I understand, but ofh doesn't seem to get on anything too hot like the vcg does on exhaust heat shield.

HTH

Doug

dmax (doug), you give some wonderful information , i think im going to take ur advice and change all of the other things you have mentioned

Originally Posted by joneperry

dmax (doug), you give some wonderful information , i think im going to take ur advice and change all of the other things you have mentioned

You'll have a good time...mostly straightforward, but keep track of the basics...I labeled all connectors with tape and name of item it plugs into...also helps you see the connectors better. Don't know how much diying you've done, but if you're going to do all of what I said, I'm hoping you've been around a car before!

Questions on anything I suggested and that you're actually going to still do... LOL...just ask! I'll get back to you as soon as I can...or one of the other 140K fanatics will, I'm sure!

Doug

Thanks Doug

I have not brought it in to the mechanic yet, but will pass on this info if he has trouble finding the leak.

Originally Posted by VECTOR

Thanks Doug

I have not brought it in to the mechanic yet, but will pass on this info if he has trouble finding the leak.

He might well just spray off bottom for you and send you on your way to return in a week with fresh drips...or you could ask him too...but, you know, you'd have to tell him to move further on than necessary now and save you the time to get to that neighborhood...but, if he hasn't done ccv before or gives you that look that tells you he hasn't...then pass on that shop for this job...think it's 2 hours for just ccv there...but they may charge more. Not to impune the credibility of your mechanic, btw, just saying there are many mechanics, but not as many that work frequently inside the same car. And many mechs would rather you take the lead on doing more than necessary to resolve your complaint. If you want to get ahead on reliability issues, you often have to manage that yourself.

Just last week a guy with an Infinity 35 something or other said that his mechanic said just oil and brakes.

Anyway, you know what I mean? Don't trust the mechanic to suggest things in the neighborhood they could do easily...they have to be careful suggesting stuff like this with customers who are uninformed and thus suspicious of shops...and I understand where this comes from...so nothing personal mechanics and shop owners...really!