The E46 common oil/coolant/fluid leaks w/ pics and part numbers thread

330ciandr6 Wrote:Ok, I have decided to make a thread depicting all of the common oil leaks on the e46 (non m3). There are numerous threads on here asking where your oil leak is coming from so hopefully this will help. Best way to determine where an oil leak is if you can't tell from tracing the oil is to completely clean all of the oil off with brake clean or something similar and and wipe it down to where its completely clean. Then drive the car for a few miles or so and reinspect and see if you can find where its leaking from (Be careful as the car is going to be hot after driving it, duh). If its a small leak a few miles may not be enough. You may have to drive the car for a few days to get enough to leak to determine where its coming from. On to the common leaks. (These are not my images, these were pulled from google images)

1. Valve cover gasket leak.
These are very very common and happen to every e46 eventually. They mostly leak on the passenger side of the motor near the rear of the valve cover on top of the heat shield for the bank 2 exhaust manifold. It will look like so:





Part numbers needed for the fix:
valve cover gasket set: build date before 9/02 11-12-9-070-990
build date after 9/02 11-12-0-030-496
Grommets: 11-12-1-437-395

2. Oil filter housing gasket
Another very common leak on these motors. This one is tough to see from the top of the engine. Most of the time you will just notice oil in the splash shield and eventually on the ground. Driver side of the motor, under the oil filter housing where it bolts to the block. I'll let the pictures do the talking. Second picture is what the leak looks like with the housing removed.




Part numbers needed for fix:
Oil filter housing gasket: 11-42-1-719-855
Crush washers: 32-41-1-093-596 (qty 2)

3. Vanos oil line
These hoses usually won't have a dripping type oil leak but will leak very slowly and start to build up residue. It bolts to the oil filter housing and to the vanos unit.




Part numbers needed for fix:
Vanos line: 11-36-1-705-532
Crush washers: 32-41-1-093-596 (qty 4)

4.Oil separator drain tube
If you have never done your oil separator and hoses, you need to at least check this hose. Most of the time this hose is severed in half and is all covered in residue. The residue can run down the dipstick tube and make it look like the dipstick tube oring is leaking. This one was tough to find a picture of one.

It is on the right in this picture connected to the dipstick tube.


Lower hose in this picture


Part number needed for fix:
Drain hose: 11-15-7-532-649
Drain hose for cold weather package with insulation: 11-15-7-532-629

5. Power steering hoses at the reservior with cap o-ring
While not technically an "oil" leak I will still cover these as they leak horribly. Some people stop the leaks by just replacing the clamps if the hoses are in ok condition while some people replace the hoses. Which you do is up to you. If your reservior is also covered in residue. Replace the cap o-ring.



This is what the reservior looks like with a leaking cap o-ring:



Part numbers needed:
If just doing clamps: 07-12-9-952-109 (qty 2)
If doing hoses:
If built before 9/01 32-41-1-095-526 and 32-41-6-796-390 along with clamps above.
If built after 9/01 32-41-6-750-155 and 32-41-6-796-390 along with clamps above.
Cap o-ring: 32-41-1-128-333

6. Oil pan
Usually only common on higher mileage cars but can happen to any of them. Now alot of times other oil leaks can leak down and around the oil pan and make you think your oil pan is leaking which is why I highly recommend cleaning up the oil and thoroughly inspecting the leak before just replacing parts.



Part number needed: 11-13-1-437-237

7. Rear main seal
Usually on higher mileage cars as well. It leaks between where the transmission mounts to the engine. This is not an e46 but is what it looks like when a rear main seal leaks.



Here is a picture of the actual rear main seal that is leaking on an e46 with trans removed:


Part number needed:
Rear main seal kit: 11-14-1-438-274
Just the seal: 11-14-2-249-533
I recommend doing the kit as it comes with the mounting plate and the gasket for the plate. Its always better to replace it while you are in there. Plus if you do just the seal you have to make sure you have it seated flush when you install it. If you buy the kit, it comes seated in the housing already.

8. Automatic transmission pan gasket
This leak will look similar to the oil pan leak except for with transmission fluid. If you have a leak on the ground near the center of the car with a reddish fluid this is probably it. The fluid can also have a brown color if it has alot of age to it. So it can easily be mistaked for oil. An easy way to tell the difference is the smell. Oil and the trans fluid have a completely different smell.

(I'm having a hard time finding a good picture of an e46 with a trans pan leak, if anyone has a personal one, let me know so I can add it.)

Part number needed for fix:
These part numbers vary greatly as there are different transmissions that have been installed in e46's. There is also multiple different fluids. To be sure of your part number for your pan gasket you can PM me or ask in this thread, just give me the last 7 digits of your vin and I can provide you with the number. For the fluid part number, there should be a label on the pan of your transmission with the fluid part number. I can also look that up for you if needed.

9.Differential output seals
These normally won't pour fluid or leave a leak on your driveway. But you will notice the leak if you get under the car and look at the diff. They leak slowly and build up residue under where the axles bolt to the diff. This is what it looks like when one is leaking.



Part number needed for fix:
Diff output seals: 33-10-7-505-604 (qty 2 needed if doing both sides.)

10. Oil pan drain plug
This leak can happen because the drain plug gasket isn't replaced when the plug is removed, because the gasket isn't there, or if the plug isn't properly tightened. It can run down the oil pan and sometimes make it look like the pan is leaking. I couldn't find a pic of one actually leaking but the plug would be covered in oil and residue all around it. Here is a picture of the drain plug.



Part number needed for fix:
Drain plug gasket: 07-11-9-963-151
Drain plug: 11-13-1-273-093 (if needed)

(damn tinypic deleting my pictures)
I'll check back and make sure the pictures stay up and don't get deleted or moved.

If you can think of anything that needs to be added or edited, please let me know.

This is one of the other power steering hoses that can leak. These leak from the crimp seams and build up alot of reside on the rubber portion of the hose.



Part number needed for fix:
For the part number on this, it depends on which pump you have installed in your car. Ever since BMW changed the style of the pump, the pressure hose changed as well. They changed where the pressure hose mounts to the pump therefore the new style hose has different bends. The new style hose part number is 32-41-6-764-725. The old style hose part number is 32-41-6-774-215. The new style hose has only one bend in the metal pipe near the pump that is about a 110 degree bend or so. The old style has 2 bends near the pump.


12. Differential rear cover gasket
This isn't all too common on these cars but it can eventually happen with age and higher mileage. On this picture...it looks like both the axle seals and the diff cover gasket are leaking. It leaks all over the cover and around the bolts. It will build up residue like in the picture.



Part needed for repair:
Bmw no longer offers a gasket for this, they stopped making it and have instructed everyone to use RTV silicone to reseal the cover.

Coolant leaks

(Some of these I couldn't find actual pictures of the leaks so I'm just using pictures of the parts)

1. Thermostat
A very common leak on e46's. Tough to see the leak by just taking a quick glance. They usually leak from the bottom onto the water pump which can make you think the water pump is leaking. Inspect the leak thoroughly and determine if it is coming from the thermostat or waterpump before replacing.



Part number needed for fix:
Thermostat: 11-53-7-509-227

2. Water pump
Another common problem for e46's. These also leak from the bottom of the housing and are hard to see taking a quick glance. Alot of times the fan on automatic cars have to come out to be able to see the leak. Be careful and like I said above, make sure its not the thermostat leaking down over the water pump.



Part number needed:
Water pump: 11-51-7-527-910