If you have a 2004 BMW 325i (M54) and it’s leaking oil, this is a very common issue with this era of engines, also know as the E46 development body style. It’s more common among the plastic valve covers, but the aluminum covers have been known also to crack with time.
To repair this symptom correctly, you must do one of two things: replace the valve cover, or the valve cover gasket.
It’s not uncommon for these plastic valve covers to crack after 10+ years of usage.
As far as availability there isn’t much choice besides going with the dealership or a trusted BMW parts store.
When you do this repair on the 2004 BMW 325i 2.5L M54, it’s also recommended to replace the valve cover gasket, spark plug seals, nut seals, grommets, and copper sealing washers.
In this article you can find 13 of the most common problems on BMW E46 models. Like any other vehicle BMW’s also have problems, the only difference is, they’re something more expensive to fix.
If getting ready to buy one, or have one and want to know what might be some of the common problems to expect in the future, this list could be useful.
Burning Oil Smell and Oil drips
Because the valve cover or the valve cover gasket on E46s will go bad around 60k miles, you’ll find this is the #1 repair on these vehicles. The most common repair on these vehicles by all means.
Failed Window Regulator
This is not a quick repair, but it’s not a difficult one. With a couple of searches online you can find some useful forum posts like this one.
Loss of Coolant
In this video you see some of the common problem areas as far as coolant leaks. It’s a quick and dirty video, but it shows you some good places to look for. Common on a leaking expansion tank.
Blower Motor Final Stage Fan Resistor Failure
If you start noticing the heater fan speed varies regardless of the setting, the fan will not turn off when the car is switched off, or the fan will not switch on at all, these are all the symptoms of the Final Stage Resistor failure.
Jolt Feeling in the Steering
This video explains how you can determine if a BMW E30, E36, or E46 3-series is experiencing control arm bushing failure. This is a common symptom of worn out thrust rod bushings in the front suspension.
Power Steering Fluid Loss
There are two commonly replaced P/S hoses on E46s. They are commonly replaced between 50k-200k miles.
Water Pump May Develop Coolant Leak
One of two things usually will happen: either it will become noisy, or it will start leaking coolant. This can cause your drive and timing belts to go bad.
Some of the common threads I found mentioned that they noticed their water pump went bad after one of the following components in their cooling system also failed; thermostat, radiator, or head gasket.
If find the same results be sure to check these items to prevent future repairs.
Noise from Top Front/Rear Doors
This is commonly hear when the windows are completely closed. The problem is caused from worn door seals. Rubber wears out and specially if you have a vehicle that’s 10-15 years old. There are all kinds of hacks out there to repair this issue, but the right thing to do is to get a new set of BMW door seals. Here are the links to the OE parts from realOEM.com:
Note: I know it's not an E46, but it should give you a good idea how to do it. This is an opportunity to make a video for it.
Coolant Leak from Radiator
It is not uncommon for the radiator to develop a coolant leak. A leaking radiator will require replacement. When a leaking radiator is replaced the entire cooling system should be inspected and if any additional leaks are found they should be repaired also.
Overheating can cause severe engine damage. If the engine begins to overheat it is recommended to stop at the first available location and have your vehicle towed to a repair shop.
Failure of Taillight Bulb housing assembly
If replacing the bulb doesn’t solve the problem, the most common repair is to do a complete rear left bulb socket replacement. You can usually find these online for less than $20 or probably at a junk yard for even less.
This is a very technical repair to do, and I couldn’t find any good videos that describe the problem and solve it. If you’re looking to learn more about it, I would recommend reading this article on troubleshooting BMW hydraulic bucket tappets. This video is a simple procedure you can try, but it’s not guaranteed to remove the check engine light.
Think you have an E46 warped valve cover that is leaking? It’s not uncommon for a BMW 3-series between 1999-2006 to show this symptom. Being that these vehicles as of today are between 10-17 years old and have about 150k-255k+ miles.
While searching around the interwebs for E46 valve cover gasket torque specs, I couldn’t find something that’s really easy to read, so I found a good source that you can use as the main Torque Specs Cheat Sheet.
One of the most common places for BMW E46s to leak oil is from the valve cover. Model for 1999 thru 2006 suffered from this issue. If you have an oil leak down the exhaust side or front of your engine, it’s likely you need to replace your valve cover or your gasket.
When the valve cover gasket leaks, it can create quite a mess and seem much worse than it is. Engine oil can also leak into spark plug hole in the cylinder head, contaminating the ignition coil boot.