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Discussion Starter #1
Hi,

I drive a e46 BMW 330ci.
The car is burning oil fast. Like 1 quart every 15 miles!
It seams to be running well, no real loss of power.
There is a very light vacuum under the oil cap so i'm a bit suspicious of CCV but could that burn oil that fast? Is piston rings more likely?
There is some smoke coming out the back. Oil used is 5W-40, car has 160,000K.

There is no smoke when I start from cold but after about a minute you can see it.

Thanks in advance for the help!
 

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Has the car ever overheated ?
 

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Are you sure you're not leaking?

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Discussion Starter #5
Yeah no sign of a leak anywhere. Its going through enough oil that if there was a leak i'm sure i would have seen it. There is some smoke coming out the exhaust anyway.
I think I will do a compression test this weekend. Does anyone know how long of a ratchet extension you need to get the plugs out? And what size socket you need to get the plugs out? My tool selection is not the best. Cheers!
 

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Yeah no sign of a leak anywhere. Its going through enough oil that if there was a leak i'm sure i would have seen it. There is some smoke coming out the exhaust anyway.
I think I will do a compression test this weekend. Does anyone know how long of a ratchet extension you need to get the plugs out? And what size socket you need to get the plugs out? My tool selection is not the best. Cheers!
You`ll need a dedicated spark plug socket, they have a molded rubber insert which grips the top of the plug. You`ll also need probably 8 or 9 inches of extension, you can put a few short ones together, just be sure to secure them (and the socket) together with electrical tape.

Take a small cardboard box, and punch 6 holes (like the size of a No. 2 pencil) in it, maybe 2 inches apart, and number them 1 thru 6. Use this to keep the plugs in the order they came out of the engine, that might prove to be important.

If the plugs are black and oily, that`s usually a good indicator that your CVV is toast....
 

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Discussion Starter #7
Thanks!. If I see low compression in one or two cylinders that could mean piston rings, valve seals, or CVV is the problem (presuming external gaskets are good). Whats the best way to diagnose between these problems?
 

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I literally just fixed a similar problem on my 04 330xi 2 days ago, a 30 to 45 minute drive at an average of 70mph, roughly north of 3,000RPMs would cost me a quart and a half of oil. There were also pretty serious shakes when cold starting, and idling. Replaced my CVV and all issues were resolved... As for how to videos, I tend to prefer the 50's kid on you tube, good pace and fairly thorough in his explanation and walk through. There is also the ShopLife videos which are pretty good, also on you tube. Good luck with the repair!
 

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Discussion Starter #10
Glad you were able to sort it out! Did it take long for the smoke to clear the exhaust pipe?
Going to do a compression test this weekend. I will post the results.
If I get good compression across all cylinders is the next best step to change the CVV? Anything else it could be?
I haven't noticed any drop in performance and starting/idling seams all good.. really hoping the rings or valve guides aren't the problem.. :/
Cheers!
 

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Glad you were able to sort it out! Did it take long for the smoke to clear the exhaust pipe?
Going to do a compression test this weekend. I will post the results.
If I get good compression across all cylinders is the next best step to change the CVV? Anything else it could be?
I haven't noticed any drop in performance and starting/idling seams all good.. really hoping the rings or valve guides aren't the problem.. :/
Cheers!
Ironically, it was the grayish smoke that first hinted at the CVV, that along with the other symptoms, brief shake or tremble at cold start, and the excessive oil burn. Within an hour of driving after replacing the CVV all hints of smoke were gone from my exhaust, and I noticed a substantial increase in performance. I've also had zero oil burn after the replacement.

Not sure if there are any other avenues to explore, but this appears to be a pretty common e46 problem. In almost every case I researched, where there were no obvious oil leaks, the symptoms seemed always point back to the CVV. - Hope this is in some way helpful, good luck!
 

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Glad you were able to sort it out! Did it take long for the smoke to clear the exhaust pipe?
Going to do a compression test this weekend. I will post the results.
If I get good compression across all cylinders is the next best step to change the CVV? Anything else it could be?
I haven't noticed any drop in performance and starting/idling seams all good.. really hoping the rings or valve guides aren't the problem.. :/
Cheers!
Changing out the CVV (or replacing with a catch-can) is always a good thing, because the original one is probably on life support at this point, and will serve no good purpose going forward. Most folks find that the old units virtually crumble in their hands as they are removing them.
When you pull the plugs, if the electrodes are dark & oily, that is usually a good indicator of a failing CVV.
If you decide to stay with a new CVV, don`t forget to replace the old oil dipstick tube (and it`s O-ring) with the new-style single-walled unit, this is a critical part of the job, and often overlooked.
 

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Discussion Starter #13
Okay so i did the compression test.

Results are as follows:
C1 - 186
C2 - 188
C3 - 183
C4 - 182
C5 - 178
C6 - 179

This gives me an average of 182.66 PSI. Cylinders are within 5.31% of each other. This seams good to me. Can I presume the engine is in good health?


With these results I replaced the CCV. Just waiting for some gaskets to dry and then will fire her up. Fingers crossed I don't need to buy more oil..

Should I consider doing an engine flush after burning so much oil in the cylinders?

Thanks!
 

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Okay so i did the compression test.

Results are as follows:
C1 - 186
C2 - 188
C3 - 183
C4 - 182
C5 - 178
C6 - 179

This gives me an average of 182.66 PSI. Cylinders are within 5.31% of each other. This seams good to me. Can I presume the engine is in good health?


With these results I replaced the CCV. Just waiting for some gaskets to dry and then will fire her up. Fingers crossed I don't need to buy more oil..

Should I consider doing an engine flush after burning so much oil in the cylinders?

Thanks!
What about the oil dipstick tube ? Did you replace that ?
 

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No.. :/

But it seamed fine. no sludge on that at all.
If you find it`s still pushing (wet) oil up into the combustion chambers, that`s probably your weak link....
 

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Discussion Starter #18
Its fixed! Woohoo. No more smoke. Thanks for your help!

I am noticing a slight vacuum under my oil cap. Where I remove the cap the car idles a little rough.
Is that normal?
 

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Its fixed! Woohoo. No more smoke. Thanks for your help!

I am noticing a slight vacuum under my oil cap. Where I remove the cap the car idles a little rough.
Is that normal?
Your creating a vacuum leak. Keep it off long enough and you'll throw P0171 & P0174. {been there, diagnosed by jfoj}..

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