[nukezero]

So after it's all said and done with the oil filter housing gaskets, I think I forgot to properly torque/tighten down one of the bolts I accidentally unbolted for no reason. I didn't need to touch that bolt but I mis-took it for a oil filter housing bolt.


Here it is, what are the ramifications? does this bolt play a role in sealing oil/coolant or does it just seem to hold the oil filter housing bracket to the block?

picture borrowed from Mr.5

[nukezero]

does anyone know if this is a one-time use bolt??? (blue marking)

thanks

[nukezero]

Here is the picture... It's kind of strange. On my car, it is a tan colored bolt with no blue marking for one time use.

On edrive90's picture, his bolt is aluminum and has a blue marking. Maybe i'm good to go, i don't need to replace it.

[JamesM3M5]

I don't know the torque spec on that bolt, but it should be a steel bolt on the N54. Tighten it down snug, should be no problem.

On the N51/52 magnesium engines, however, they are one time use aluminum bolts that are known to break all on their own.

[wroom1]

Exact same thing happened to my 06 E90 while checking for oil leaks. this bolt with washer marked by blue arrow was broken. Do you guys know if this could also lead to oil leak? I know my oil filter gasket is leaking oil. I would greatly appreciate if someone could share their expertise on this issue. I couldn't find the part no. for this bolt on realoem.com
Nukezero; thanks for bringing this up

[nukezero]

So I found out that the bolt that I have is actually steel. In other pictures I saw, it is silver aluminum with a blue marking. That means it is only one time use.

So lucky for me, I didn't have to buy new bolt since I cracked it open. I torqued it down to 27 ft-lb and called it a day. According to the manual, it appears to be part of the cylinder head where it mates to the bottom of the block. You can see a gasket between that, which is presumably the headgasket.

For those of you who weren't so lucky and need this bolt, the dealer part manager actually called me back and told me she found the bolt part number. It is actually a part number with several other bolts for the cylinder head.

The part number is: 11-12-7-574-303

[wroom1]

Thanks Nukezero good thing is that these aluminium bolts (Set of alu. screws f cylinder head) are not expensive now need to find time for this DIY--

[JamesM3M5]

If you have an N54, this bolt is steel. If you have an N51/52 engine, it is aluminum. If it is broken, you must also remove the valve cover and VANOS units from the camshafts to replace the other two bolts in the set of 3. If the one you can see is broken, the other two may also broken, and they are hidden under the VANOS units. You will need the N5x cam setup tools to do the job.

[wroom1]

Hi James, I think it is an aluminium bolt (N52 engine; 06 325i). I don't see any oil leak from any other part of the engine or valve cover gasket. It's leaking from oil filter gasket. Do you think this broken bolt has to do anything with the oil leak? Is it a part of oil filter housing or valve cover? I will post the pictures soon.

[wroom1]

Here is the pic oil leak is only on this side of the engine. Is there any ways to pull out this bolt? Not sure why BMW uses these alu bolts on engine block!!!

[BMWM.D.]

Originally Posted by wroom1

Here is the pic oil leak is only on this side of the engine. Is there any ways to pull out this bolt? Not sure why BMW uses these alu bolts on engine block!!!

Yep, on the N52's you can get a nasty oil leak when that bolt breaks. It's actually one of the head bolts.

The reason for the aluminum bolts is that the N52 uses a composite magnesium-aluminum crankcase. Magnesium and steel don't work well together. There are some locations (transmission bellhousing, etc.) that use alumimum bolts but are threaded into the aluminum insert portion of the block. Why BMW didn't use regular steel bolts in these locations is beyond me. Possibly to avoid confusion as many of the bolts on the engine DO thread into magnesium.

[Fritzer]

Do these bolts break on their own?