Help diagnosing oil leak (pics attached) - A/C compressor??

Hi folks, I'm trying to locate the source of an oil leak on my e90. Recently noticed a small spot on the garage floor and a nasty buildup of gunk down near the serpentine belt and A/C compressor. My first thought was valve cover gaskets, but I had them replaced very recently.

Dropped the underbody panels and looked around. Found a significant amount of grime and oil on the A/C compressor and surrounding area. Underbody panels showed evidence of a consistent drip in that same area.

For those familiar with working on the S65, is this a common area for oil to leak? Is the A/C compressor even connected to the oiling system? Does it seem like I cracked the case or is there likely more to the story, and if so, what should I look for next?

Much appreciation to anyone who can help!

Oil filter housing gasket right above all that is the culprit. Changed mine not too long ago because I had the same leak/grunge build up.

Ajolives wrote

Oil filter housing gasket right above all that is the culprit. Changed mine not too long ago because I had the same leak/grunge build up.

Thanks for the quick reply. How tough was it to change the gasket? Did you DIY? Now that I look from the top down, if I reach my hand down the front of the filter housing there's a bunch of grime down low, but totally dry up top near the cap. Is that consistent with yours? Is the gasket down low near the bottom of the filter housing?

Sorry for all the noob questions, haha.

Eja144 wrote

Ajolives wrote

Oil filter housing gasket right above all that is the culprit. Changed mine not too long ago because I had the same leak/grunge build up.

Thanks for the quick reply. How tough was it to change the gasket? Did you DIY? Now that I look from the top down, if I reach my hand down the front of the filter housing there's a bunch of grime down low, but totally dry up top near the cap. Is that consistent with yours? Is the gasket down low near the bottom of the filter housing?

Sorry for all the noob questions, haha.

Yeah you won't necessarily see it from the top, the gasket sits between the block and the filter housing, so you have to remove the filter assembly, which is a good time to say the least as there's a bunch of stuff in the way.

I did it myself and it wasn't too hard at all, took me about 7 hours, but I like to take my time especially with stuff like this. So expect hefty labor charges if you bring it to a shop.

There's a couple threads out there about it and I used this one mostly.

https://www.m3post.com/forums/showthread.php?t=1312849

You will need to grind down a T30 torx to get a bolt hiding behind the harmonic balancer.

I also installed a underdrive pulley kit and replace idler pulley while in there because that stuff will come off too!

Ajolives wrote

Yeah you won't necessarily see it from the top, the gasket sits between the block and the filter housing, so you have to remove the filter assembly, which is a good time to say the least as there's a bunch of stuff in the way.

I did it myself and it wasn't too hard at all, took me about 7 hours, but I like to take my time especially with stuff like this. So expect hefty labor charges if you bring it to a shop.

There's a couple threads out there about it and I used this one mostly.

https://www.m3post.com/forums/showthread.php?t=1312849

You will need to grind down a T30 torx to get a bolt hiding behind the harmonic balancer.

I also installed a underdrive pulley kit and replace idler pulley while in there because that stuff will come off too!

Excellent - looks like a pain in the ass, but doable. I'm guessing an Indy shop would put a nice hole in my pocket for labor so I'll probably try this one myself.

Thanks for all the info man - really appreciate it.

Did you have to remove the harmonic balancer to get the housing off?

Ah never mind, seems like that's why you need to cut the torx bit, to squeeze it behind the balancer?

No problem dude, glad I can help. It's 100% doable, just a bunch of stuff to unbolt and it's a messy job.

The hardest part for me was getting my ps pump pulley off, it wouldn't budge at all. I ended up breaking it in the process, but thankfully the Macht Schnell kit replaces it so I wasn't down a part. There was also some corrosion that needed to be cleaned up around the thermostat and water pump mating surfaces.

Other than that it's pretty straight forward.

Eja144 wrote

Ah never mind, seems like that's why you need to cut the torx bit, to squeeze it behind the balancer?

Yup, I just took my dremel and chipped away at an old bit. I ended up using vice grips to hold the bit to break the torque, after that it was able to be backed out by hand.

Ajolives Scrippy

I'm working on putting together a shopping list for this job. Looks like both of you guys ended up replacing several additional items, i.e. belts, tensioners, pulleys, etc. Seems like a good idea since I'll have the thing apart anyway.

Would you happen to have a list of part numbers handy (or even just the names of the parts so I can look it up on FCP?).

Ajoviles – would you recommend the Macht Schnell underdrive pulley kit?

Thanks so much!

I highly recommend the MS Pulley kit as it comes with new belts which are a standard size and can be bought anywhere versus the others on the market. Pay close attention to your production date to get the proper kit as they vary slightly. Super easy to install.

I also replaced the thermostat and water pump. I wasn't going to initially, but I noticed my old pump's pulley had a wobble to it when I was getting my list together, haha. FCP euro has a kit available with the parts, gasket, and coolant.

Idler pulley and belt tensioner are also on the list from FCP euro. I think that's all I replaced. You can replace the oil cooler line gaskets too, which I forgot to do.

I changed my oil and put in a about two liters of coolant 50/50 mix. Woulda been less but I had the front of my car jacked up a bit (so I didn't have to bend over as much) and a healthy amount of coolant from the thermostat hole dripped back into the V of the engine and down.
So don't do that.

Add a can of engine degreaser and plenty of shop towels too!

Eja144 wrote

Ajolives Scrippy

I'm working on putting together a shopping list for this job. Looks like both of you guys ended up replacing several additional items, i.e. belts, tensioners, pulleys, etc. Seems like a good idea since I'll have the thing apart anyway.

Would you happen to have a list of part numbers handy (or even just the names of the parts so I can look it up on FCP?).

Ajoviles – would you recommend the Macht Schnell underdrive pulley kit?

Thanks so much!

I’m about to tackle this, but not with underdrive pulleys. I have a list on fcp that you can reference as well. Send me a pm and I can email or text a picture. I’m replacing pulleys with parts found so I didn’t have to buy the Bmw pulley assemblies. I can provide links to the threads that have that info. What year is yours? The idler pulley is different for early 08 models. Older 08s have an offset hole in the idler pulley, later models are centered. Belts may also be different.

Eja144 wrote

Ajolives Scrippy

I'm working on putting together a shopping list for this job. Looks like both of you guys ended up replacing several additional items, i.e. belts, tensioners, pulleys, etc. Seems like a good idea since I'll have the thing apart anyway.

Would you happen to have a list of part numbers handy (or even just the names of the parts so I can look it up on FCP?).

Ajoviles – would you recommend the Macht Schnell underdrive pulley kit?

Thanks so much!

Here's a list of the idler pulley part numbers and a couple of the different places to purchase them.

DIY: idler pulley replacement [#47]

Eja144 wrote

Ajolives Scrippy

I'm working on putting together a shopping list for this job. Looks like both of you guys ended up replacing several additional items, i.e. belts, tensioners, pulleys, etc. Seems like a good idea since I'll have the thing apart anyway.

Would you happen to have a list of part numbers handy (or even just the names of the parts so I can look it up on FCP?).

Ajoviles – would you recommend the Macht Schnell underdrive pulley kit?

Thanks so much!

I just used realoem.com. Put your VIN last 7 in and it will only show you your specific parts so there is no question if it is correct or not. They have exploded views of every part on the car. It's just a matter of finding the section containing your parts and diagrams. Then take the part numbers to FCP's site. Just remember to suck the oil out of the housing before you break any bolts loose on the housing or you will have around 12-16oz of oil fall down the front of the block. As long as you follow the torque specs you will have no issues. Do not mess with the harmonic balancer, cut a torx bit and use an open end wrench with it for the one bolt that is super close to the balancer. I put pictures in my post to show what I mean. Super easy and I would put it at 4 out of 10 difficulty. Fill the oil housing to the threads after you put a new oil filter in to avoid a prolonged dry suck on startup.

I just changed mine on my motor but it take more time to dremel and cut ect then it does to just take the front of the car off.

drain your radiator, drain your oil from the pan and from one side of the oil cooler.

disconnect all lines, to main on the rad to engine block

pull rad out. then pull the front clip off with all headlights and radsupport intact

Its only held on with 12 bolts. 4 in the top of the fenders 13mm and then 4 on the crash bar on each side. you can disconnect your ac condensor from the holder and let it hang so you don't have to open the system.

it only takes about 2 hours to take everything off down to the balancer and all.

Hey guys, I appreciate all the replies/advice! Been busy with work but will catch up as soon as I can.

If you decide you dont want to diy, im in queens.