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Old 09-09-2018, 10:51 PM   #1
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Join Date: Nov 2017
Location: Mountville, Pennsylvania
Posts: 3
My Ride: 2004 325XI Touring
2004 325xi Touring Leaking Oil, Burning Oil, and has a Misfiring Cylinder

I apologize for this being so long, so there's a summary near the end, as I tend to add too many details.

So I bought a beautiful 2004 325xi Sport Wagon last November, and shortly after my purchase I would notice a slight to moderately bad burning oil smell coming through the AC vents with the heat on, and most often occurring when it was raining or cold outside. Sometimes after a long drive I could even see some light smoke coming through the hood (I'd always check to be sure it was just the oil). Since then I have also found that after revving it high or driving it hard, 80 - 90mph on the highway for more than 50 miles, I end up losing between 3 and 5 quarts of oil. Never have I once seen oil under a spot I parked my car though, so I can only assume it all comes out as I'm driving. I believe the engine takes 6.9 quarts though, and I'll pull the dipstick to check afterwards finding it at or below the 'low' line. Adding 5 quarts will bring it back to or above the max line, not sure why. But since then, I've simply dealt with the oil issue. Fast forward maybe 3 months and I had my coolant leak every few days for maybe an 8 week long period of time, and discovered that was just the coolant thermostat valve getting stuck (this is what my 'car friends' tell me, I'm not too mechanically inclined). But just recently, as of 2 weeks ago, I was on a two hour drive to visit family and after about an hour of driving I could feel the engine kind of shaking when in 5th gear (in severity on a 1-10 scale, I'd say a 6), and it felt like it was struggling with acceleration (I was maybe going 70, and it somewhat slowed to around 60). I would slow down to between 55 and 60mph, going into sport mode to force the vehicle back into 4th, where everything was once again fine. In 5th though, it was struggling to accelerate, it felt pretty badly underpowered, and wasn't revving very much past the low 2000s. Car friends said it sounds like a cylinder misfiring, and by what I've read that sounds right. So I let the engine idle the other day and unplugged each spark plug one at a time to see if one in particular wasn't working, but each one made the engine sound barely underpowered, all an equal amount, making them all seem fine. One car friend suggested that maybe one of them is only failing when already under a good amount of strain, in 5th gear for example. I just blow torched and wiped down all my spark plugs 3 days ago, (the sparking end and the threading), which had a medium amount of oil on them. After that, I had to attend a family funeral, so driving another 2 hours, and this time I could feel the engine become 'underpowered' in 5th gear for maybe only a 5 - 10 second period, and only once during the drive. I can still feel the engine shaking a tiny bit when I switch to Drive/Reverse, but it feels normal in park. This never happened when I first bought it, so I'm not sure whats happened since then.

In short: Bought an E46 10 months ago, I soon found that it burns and leaks oil, but only after a hard run or when revved pretty high (hard run being 80+mph for more than 50 miles). It also happens to burn oil regardless of how I run it during cool or humid weather, and almost every time when it's raining. Fast forward maybe 2 months, and I've simply been dealing with refilling the oil, but I also experienced an 8 week long period where my coolant was leaking out and I had to keep refilling it. That stopped and hasn't reappeared since. Just 2 weeks ago I was making a 2 hour drive to visit family and after an hour of driving on the highway, (averaging about 85mph), the car started to shake moderately and had trouble accelerating in 5th gear, (was fine in 4th going 60mph). I was told it sounds like a misfiring cylinder, so I cleaned the spark plugs thinking maybe refilling the oil had somehow affected them, and on my next family visit the car shook only once for maybe 5 - 10 seconds. I force it into 4th with the sport manual mode to make it stop, (I don't do more than 60), and then I can sometimes resume normal driving after putting it back into automatic mode.

Some important details:

- Bought with 169,800 on it, it currently has around 182,300
- Due to the high revving oil issues, I drive like a grandma in it, except when I'm in a hurry, never pushing past 90 (but I ALWAYS accelerate slowly)
- To get better efficiency, I constantly accelerate lightly and let off to maintain a specific speed (not sure if this is important)
- I never allow the gas tank to dip below 1/2 (I heard this was good practice)
- I use 5w-30 oil, in case that's relevant
- I've refilled the oil on average every 3 - 8 weeks, depends on the miles & the strain
- I've never once seen leaked oil after moving from a parked spot, so I assume it only comes out while driving (I can lose 3 - 5 quarts at a time)
- I regularly check all fluids, always at least biweekly
-I never tended to the coolant leak issue, as it stopped on its own and I was told it isn't a big deal (plus I rarely have time)
-OBD reads out a 'Coolant Thermostat Temp below Regulating Temp' (P0456) and 'Very Small EVAP System Leak' (P0128)
- Whatever I can do to save money while not ruining my car, I will
-Model again is a 2004 325xi Touring Sport Wagon with an M54 engine (2.5L)

Most importantly, I cannot thank you enough if you take your valuable time to read either of those and help me out, as I love this car and am scared shitless about what could be wrong with it. Again, thank you so much to everyone willing to share their knowledge & thoughts.
BimmerLoverE30 is offline   Reply With Quote
Old 09-09-2018, 11:54 PM   #2
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Join Date: Jul 2018
Location: Valley Village, CA
Posts: 49
My Ride: 02 325iT
Year: 2002
Model: 325i Touring
Transmission: Auto
That is a LOT of oil loss. The most likely culprit is a leaking valve cover gasket, which would drop oil onto the exhaust manifold(s) and smoke like hell. Worse, if the valve cover spark plug gaskets are bad, oil will also drip into the spark plug wells. There is a gasket on the oil filter housing that's a known leaker. Last, but not least, is a bad rear main seal, which might not leak much while the car is sitting, but will while the crank is turning. I wouldn't think it's the oil pan gasket or drain plug, because the gasket would mostly leak when full, and the drain plug would leak at all times.

Do some investigating with a flashlight around the top/rear of the engine (when it's cold), feel around for wet oil. Crawl under the car and see what looks oily.
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Old 09-10-2018, 06:17 AM   #3
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Join Date: Dec 2013
Location: Elizabethtown, PA
Posts: 2,717
My Ride: '03 325i Touring
While these engines are known to have oil consumption issues, that it is absurd. When the dipstick reads below the safe markings it should only take 1-1.5 qts to get it back to the full mark. I had a 2001 that used a quart about every 400-450 miles, so I basically put a quart in @ every fill up. The main culprit is gummed up piston rings from poor maintenance. It can also be caused by a failed oil separator in the CCV system. I would recommend replacing the CCV system as a start, as well as the valve cover gasket mentioned above. While the coils are out for the valve cover gasket I would also recommend replacing the spark plugs, as you're better than half way there. If you're adding 3-5 qts of oil at a time you need to be checking it more frequently or you are definitely hurting the engine. As I said earlier, though, there would be zero oil reading on the dipstick at that point.

Do you have any maintenance history on the vehicle? If not it's time to start all the basics, like a cooling system replacement, especially with that thermostat code. Spend some time reading on here in the general forum and you'll find lots of info on basic maintenance and DIY guides.

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325xi, e46, high milage, misfire, oil

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