Assistance requested. Q about oil loss, here's what I am seeing...

[EricV]

Hi folks. First off, my thanks to everyone on this forum in advance. I used to rely heavily upon this place a few years ago, but kind of fell out of touch. Second, I am very sorry this is so long- I wanted to be as complete as possible.

I still have my 1993 M50 525i (manual trans.) and it's currently at 107K. Here's what I am inquiring about. Please bear with me, as I also have a Q about how the PCV system may play a part...

It seems to "dump" oil (about half a quart) once every 500 miles or so. I say "dump" b/c the oil level ever so slowly lowers, but then all of a sudden it drops suddenly. I have been over and over this engine for five years- it has some seepage that seems historically unchanged where the head meets the block, and it also seeps from the oil filter canister lid- but very little and at high revs (I have tried and tried to stop this, short of using Permatex or paper thin gasket material.) In short, I don't think these things account for my loss, especially the sudden drop in oil level. It also does not appear to burn oil. I am, by the way, using Mobil fully synthetic. I also had to change my valve cover gasket about 2 years ago (at about 90K) as it was leaking oil into my spark plug holes. That seems remedied.

Now one thing I did notice, over the past 10 months or so, is that there seems to be some kind of blow by that appears to be oil coming from the little rubber tube that attaches to the manifold directly to the right of the throttle body- facing it from the throttle body side (driver's side) of the car. This little tube to the right of the TB shoots whatever right into the manifold, and again I see some kind of over spray that appears to be oil on the manifold where it connects. About 2 inches before where this tube terminates and in line w/ the total tube is a white plastic piece shaped like a childs spinning top.

Is this stuff part of the PCV system? My guess is that it is. Could this blow by oil be part of my oil loss issue? What might this blow by be indicative of (please don't say it's a terminal issue. :) I sure would appreciate any guidance.

I have also had an on-going gradual loss of coolant issue since I bought it. Can't find it anywhere- I have checked and re-checked all suspect areas, replaced the radiator/pump, etc. My mechanic has thrown up his hands also. The issues do not appear, I stress appear, to be related. No telltale mixing of coolant and oil, odd smoking, or anything like that. Our guess is that it's seeping some place we can't see it and burning off, leaving no drips or other tell tale signs.

Do any of you M50 owners have a similar problem? I'd love to hear from you.

Overall the car is still strong. I struggle with keeping it though as I fear it's going to become costly soon. At about 90K I had all kinds of things done- flushed out all fluids, plugs, all filters, guibo, clutch, radiator, water pump, aluminum water pump housing installed, EAT chip, M5 sways, and a suspension kit installed also. Overall a nice car, but again I am growing fearful of it.

Last Q, I promise. I get a knocking noise (metallic engine knocking) upon acceleration from about 2-3K rpms most obvious in lower gears. been doing it for a long time. Could the EAT chip be causing some kind of detonation problem? Again, it doesn't appear to burn oil, so although it sounds like piston slap I don't think it's a major issue. Any input here also appreciated.

My sincere thanks to all who read through this. :) I am at work, but will check back here later this afternoon. Have a good one!

Eric

[EricV]

moves it back to near the top of the threads for best visibility. Thanks!

[ryan roopnarine]

please use this diagram

http://www.realoem.com/bmw/partgrp.do?model=HD53&mospid=47404&hg=11&fg=40
or enter your own vehicle data into www.realoem.com/bmw and go to "11 engine" then "11.40 intake manifold" to point out to us which one of the lines you are referring to. i've been under the intake manifold a fair bit, and my car does not appear to have any white fittings.

[EricV]

only one rubber hose going into the manifold just to the right of the throttle body, and I know for a fact that my car is a late '93 M50 Vanos engined 525i. I do appreciate the link though- great site. I guess what I'll have to do is get someone to take a digital pic and then I'll try to figure out how to post. I do appreciate your attempt to help- I thought that with something this basic (i.e. one tube, the only tube, to the right of the throttle body) it would be straightforward. Alas, perhaps it's with BMW's as with other cars- no two are alike! :)

Eric

[EricV]

parallel to the ground, straight into the same side edge that the throttle body mounts into, near the top edge so that the "blow by" oil actually mists up on top of the manifold. FWIW... :)

[ryan roopnarine]

does your car have the electronic throttle maybe? i don't know if that is different, but it might be the cause.

[ryan roopnarine]

if you are talking about a 3/4 in fitting that is directly behind the throttle body and has a big and a small hose coming out of it, you are referring to item 10+9 in the diagram. if it is leaking from the mating surface between the manifold and fitting, as you can see from the diagram, there is an o-ring that goes in between there, and that might be the cause. ill wait and see if this is what you are referring to.

[EricV]

took another close look at the diagrams, but again it just doesn't represent my set up. I see what you are talking about (10-9) but that seems to be on the "inside" or underneath the intake manifold. The hose I am referring to, at the risk of being redundant, is the only hose on that same flat side of the manifold (the same flat side the TB bolts to) to the right of the TB if standing on the drivers side facing the TB. For instance, you're looking at the TB and then, just to the right and the only thing there, the hose connection I am referring to.

I'll see if I can't get my buddy to photograph it this weekend and I will see if I can post it.

Ryan, I know how frustrating it is to do this by description, and again I really appreciate your willingness to help and your patience!

Have a great evening-

Eric

[ryan roopnarine]

its the brake booster hose on the same side. now i know what you meant by "white" and "looks like a top". it isn't in that diagram. its the thing with the irremovable hose clamps. it may just be that they are tired. you or your mechanic can pry them off and put adjustable hose clams on there if it is leaking from where the hose meets the manifold.

[EricV]

...and I am ashamed to admit I didn't realize that before. :) I was so focused on the end with what appears to be oil spray coming from it and assumed it was a part of the PCV system. So, given this (that it's a vacuum hose and there's some kind of oil blow by coming from it) any idea what it is and if it is something to be concerned about?

Also, and not to take advantage of your kindness and expertise, any idea on how to approach my oil loss issue as well as how to approach the detonation issue (i.e. in what order to start attacking/troubleshooting... knock sensors first? etc., etc.?)

Many thanks!

Eric

[Ross]

It sounds like excessive blowby if you are using a quart in 500 miles, are you sure it doesn't smoke?
The knocking you describe could be detonation which is very destructive and could certainly account for your blowby if it's been going on for a while.
Off the top of my head it sounds like maybe a broken ring or burnt piston.
Do a leakdown test to check the health of your motor.
I've gotta know why you would drive a car "at high RPMs" if it makes a knocking sound?

[ryan roopnarine]

...and I am ashamed to admit I didn't realize that before. :) I was so focused on the end with what appears to be oil spray coming from it and assumed it was a part of the PCV system. So, given this (that it's a vacuum hose and there's some kind of oil blow by coming from it) any idea what it is and if it is something to be concerned about?

Also, and not to take advantage of your kindness and expertise, any idea on how to approach my oil loss issue as well as how to approach the detonation issue (i.e. in what order to start attacking/troubleshooting... knock sensors first? etc., etc.?)

Many thanks!

Eric

any of the vacuum hoses will have "blowby" come out of them when they get old and can no longer grab on to the nipples. removing the permanent clamp, putting an adjustable clamp on it, and tightening it down will probably fix it.

what kind of "knock" are you experiencing? is it like an old chevy that has never had its oil changed and now has slap? or is it like medium load/ lugging engine ping?

take your finger and put it parallel to the back of the oil cannister. drop itdown until you hit the nook(cranny?) ofthe oil filter housing unit. is there a little mL of oil pooled down there?

[EricV]

words more carefully.

First off, it doesn't typically use a quart over 500 miles. I should have been more clear. Over the course of 500 or so miles, my oil level will ever so slightly, and incrementally, drop just a bit, a hair on the dipstick. That's fine- it's an old car. Every now and again, I get this "dump" issue- all of a sudden the level just drops off steeply and suddenly. That's the issue that has me puzzled.

Secondly, as you "gotta know," I do not drive any car at high RPM's with a knocking noise. Not sure what gave you that idea. It's audible at low RPM's upon acceleration. At idle, it sounds great, as well as at higher (not high, mind you) rpm's. Smooth overall. Being an older car, it usually stays within the 3-4K range.

Thanks for your input, I am sure I'll be doing a leakdown test at some point in the near future. It passed the past one with flying colors about 15K ago. Still, it's old and I would imagine it's up for some serious work, in spite of all I have done to it. That age old dilemma...to keep or to sell....

Eric

[EricV]

nook/cranny you mentioned as I did see, yesterday during another "search," a reference to this being a possible source. Perhaps it is leaking there and burning off also.

I hate to say it, but of the two choices it sounds more like the Chevy you described. A little loud under load (I can only hear it if, say, it's echoing off a building right next to me as I accelerate from a light.) It's just audible at those lower rpm's as I pull off. Smooth at idle and at higher rpm's. I am just curious how I should approach the issue- start with octane boost, switch back to my stock chip, perhaps test components, etc. Just looking for guidance so I can approach this efficiently as I have limited time and access to a garage and my tools. I am sure I'll also be doing a compression test soon, although it passed about 15K ago.

Again, many thanks.

Eric

[Ross]

It's really tough to diagnose noises in this manner but here goes.
Is the sound the same when cold as when fully warmed?
Does the "knock" get worse under load?

I misread your 1/2 qt. as A qt., sorry. Thats still excessive though. Are you reading the oil level under the same conditions each time? Since you mention occassionally maybe it's only the car not being level.
What was the reason for the leakdown test 15k ogo?

[EricV]

patience and attempts to work through this. Again, I am simply trying to learn what it MAY be and, more to the point, a plan of attack so I am not wasting time- basically an order of troubleshooting to get started.

The knocking is the same if cold or hot (engine temp) and it's clearly under load, like starting out in 1st then 2nd gear. Below that (at idle) or above that (at higher speeds in higher gears) the thing sounds great. Now I have to admit, I may just not be hearing it at higher speeds/gears. It's definitely prominent under load though. I think my fuel lines may be leaking (been noticing a smell at start up this summer, which disappears when engine is up to temp) so I am wondering if running lean may be doing it.

I always check the oil in the same spot, a level spot. I'm very anal about this. It is very puzzling though. The incremental loss I can expect/accept as I know I have that seepage from the filter canister lid (at higher revs) but the sudden drop in level- only occassionally- is what puzzles me. It's sudden and substantial. How do I know this? B/c I have checked it routinely in the past and then, a few days later my oil warning comes on and I check it again and bam, it's down by like 1/2 a quart. That's why I called it "dumping."

Again, I appreciate your time and patience. I just want to develop a plan of attack as my mechanic seems to lack the interest (I guess they're busy with cars that are clearly broken and rushed to be fixed) and I also want to get a better feel for it myself- and hopefully fix these issues. If I could get these things worked out, I'd be more interested in keeping the car.

Thanks!

Eric

[granit_silber]

I can't help with the oil issue, but I do have a tidbit for you.

In a recent Roundel (maybe the September issue) the guy that does tech talk (can't remember his name right now) mentions that M50 seems to eat coolant and that he doesn't know why.

I have a non-vanos M50 that does eat coolant. My engine, doesn't have any cooling problems and no leaks. It just seems to be how things are with the M50.

-ashley

[EricV]

nt
I can't help with the oil issue, but I do have a tidbit for you.

In a recent Roundel (maybe the September issue) the guy that does tech talk (can't remember his name right now) mentions that M50 seems to eat coolant and that he doesn't know why.

I have a non-vanos M50 that does eat coolant. My engine, doesn't have any cooling problems and no leaks. It just seems to be how things are with the M50.

-ashley

[ryan roopnarine]

i've been losing coolant for a year or so. i just had a coolant hose burst on me, one that goes from the throttle body/air box to the head. i changed it out, and now my coolant level stays solid no matter how hard i drive it (and this is despite a slight weeping in the radiator at a bottom seam). i didn't see that it was leaking coolant because the nipple for it is under the manifold, and the dirt/heat under there masks it well. i don't think it is normal to say that the m50 "eats" a nominal amount of coolant.

about the level drop of oil. does it drop like this within the last 500 miles before oil changes? though it isn't exactly comforting, it isn't out of the ordinary for oil consumption to go up as contaminants break down the oil. mine uses maybe 1/2-5/8 of a quart of dino per 2500 miles (and that's because of the oil canister leak) but in last 500-750 miles ofthe oil's life, it will drop about 1/4 to 1/2 a quart. i drive my m50 likely more than any one else here, and see the car do the same thing with synthetic around 5500 miles, so ihave the first hand experience to not be worried by it.

[EricV]

"eat" coolant, but I guess it's comforting to know I'm not alone.

Nope- no rhyme or reason, I wish it were as predictable as yours. I'm about 1K into my oil interval (changed about 1K ago) and this is the second "dump" I have experienced. If I had some idea of where it was going, I'd feel better. As it is now, I just don't trust the car to go farther than say 30 miles at a pop.

I guess I will go ahead and schedule the car to go to Richmond VA for leakdown and other diagnostics, about an hour away from me. There's a reputable independent mechanic there I should try. I'm just trying to gain as much info as possible before handing it off to another mechanic to try to save some money. I am so heebed out by this car, at this point, I just want to unload it for whatever I can get out of it- which will not be much unfortunately.

My thanks to all- I will keep you posted!

Have a great evening-

Eric

[Ross]

Lean running will certainly cause detonation.
You may have issues with the carbon canister and it's purge on start-up if you are smelling fuel at start-up. I tried looking at realoem to see the part in the vac. line you mentioned earlier but it isn't shown. I can look at my own car later to refresh my feeble memory.
Are you using good fuel? Perhaps a knock sensor has gone south?
Try plugging the crankcase vent line on the manifold side and open the oil filler, watch for smoke coming out and see if you are getting crankcase pressure by holding your hand over the filler hole. Crankcase pressure and smoke are bad and a sign of worn or broken rings. Your noise could be a piston rattling about.