Different sound after oil filter housing gasket change

[cozmicf]

Hey guys, I got the oil filter housing gasket changed on my 2011 BMW 135i by a mechanic today (because I found an oil leak around there) and noticed it sounded different after. I've only had this car for about 8 months so I don't know exactly what it used to sound like brand new.

The videos below have two different sounds that I had not noticed below. Can anyone identify them? Is this normal after an OFHG change?

1. Sounds like something spooling up when I rev it but not very smoothly (would turbos be affected at all by an OFHG change?):

2. Seems to come from under the engine cover, sounds like a more pronounced diesel-y sound than before (mostly in the second half of the video):

Are any of these sounds normal? I will probably take it back to the mechanic to get it checked out.

[Stewy_604]

Sounds completely normal to me.

[Matticus91]

Is your oil level good? Any leaks? Car throwing any codes or driving differently?

They have to remove, or at least partially remove the intake manifold to get one of the bolts for an OFHG change - it's possible they missed something when they put it back together.

The first video definitely sounds a little weird, the second one seems normal. These engines make a ton of not-so-savory sounds under the hood.

The first video almost sounds like the turbo isn't regulating pressure correctly, but if that was the case it would definitely be noticeable when driving.

[Neiman Levenson]

i agree with matticus, the intake manifold is extremely sensitive. I took mine off for carbon cleaning and was in a world or hurt when I re-installed it.

Ultimately, you need to use the exact torque specs and order of torquing the bolts to ensure that the manifold seats 100% with no small or faint leaks. I even had to get to new intake manifold gaskets and follow the protocol 100% to make sure it seated right and didnt give me any leaks.

your mechanic probably knows this about intake manifolds though. The usually "good and tight" or star pattern. will not cut it when torquing down the intake manifold. you have to follow exact spec is what I found

[Dackelone]

2nd video sounds normal to me. Some cars can such air thru the rear crankshaft seal. Maybe your OFH was leaking so much that now your engine has more vacuum at idle - hence the different sound to "your ears"... which is completely normal to "our" ears.

[cozmicf]

Thanks for the info everyone. I haven't gotten any DME error codes, and the oil level sensor hasn't gone off. The car drives the same as far as I can tell, and I don't really notice any decrease in power.

I haven't noticed the noise from the 1st video in a while now, so maybe it was something that only happened for a while after the OFHG change and isn't really a problem? I will try revving it again tonight to see if I hear the noise again.

Is there any easy test for checking for leaks? Would an MHD log help?

[brytom]

Check for vacuum leak or boost leaks?
In stock form, it should be giving you codes right away for low boost pressure if there was an issue. They are multiple sensors checking boost pressure. I don't think there is anything on the intake side that requires vacuum that it would have been touched. Only vacuum items are the turbo and exhaust flap.
In stock form, you don't need to do much if you're careful. Remove the microfilter trim, remove the air box, move some harness out of the way. I take shop air to knock any debris from falling in to the intake ports of the head. Take out the seven bolts/nuts for the intake and slide it up an inch. There is no need to to touch the DME nor the charge air pipe or throttle body.

Edit:
I forgot the main vacuum line runs from the pump over the intake to the vacuum reservoir built in to the valve cover. You can try remove the acoustic cover, should be two push down in the front you can pull up on and pull the cover forward and out of the slides built in to the intake pipe. Check the hose if it is snapped in properly and the hose after the bend down below the intake is cracked or broken. I doubt there is an issue, as a vacuum leak before the reservoir will cause issues with the exhaust flap and the wastegate, meaning you would have boost pressure faults.

[cozmicf]

Originally Posted by brytompkins

Check for vacuum leak or boost leaks?
In stock form, it should be giving you codes right away for low boost pressure if there was an issue. They are multiple sensors checking boost pressure. I don't think there is anything on the intake side that requires vacuum that it would have been touched. Only vacuum items are the turbo and exhaust flap.
In stock form, you don't need to do much if you're careful. Remove the microfilter trim, remove the air box, move some harness out of the way. I take shop air to knock any debris from falling in to the intake ports of the head. Take out the seven bolts/nuts for the intake and slide it up an inch. There is no need to to touch the DME nor the charge air pipe or throttle body.

Edit:
I forgot the main vacuum line runs from the pump over the intake to the vacuum reservoir built in to the valve cover. You can try remove the acoustic cover, should be two push down in the front you can pull up on and pull the cover forward and out of the slides built in to the intake pipe. Check the hose if it is snapped in properly and the hose after the bend down below the intake is cracked or broken. I doubt there is an issue, as a vacuum leak before the reservoir will cause issues with the exhaust flap and the wastegate, meaning you would have boost pressure faults.

Thanks for that. I think it should be ok given that I haven't seen any other symptoms or codes, and the car drives the same. If I start having problems I will give that a try.