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Old 01-09-2014, 03:22 AM   #1
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E30: 91 318i
Location: Yorba Linda, Ca
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Default Oil Filter housing oil leak repair (m42)

My lovely little e30 318 has had an irritating oil leak for quite a while. After resolving pretty much everything else it could be I was still getting quite a bit of a mess under the car, on the PS fluid reservoir, and none above the canister for the oil filter.

I've also found that quite a few others feel that besides the valve cover gasket this is one of the most common leaks.

This is a relatively quick and easy job to be honest. You'll need the following parts:

Oil Filter housing gasket, Part Number: 11-42-1-709-800
Oil Filter housing o-ring (only 1 needed) P/n: 11-42-1-709-513
Brake/carb cleaner (optional but I like the clear around my work area before opening any sealed areas of the engine
copper gasket sealer, again optional but I've had great luck with it and makes for installing paper gaskets a bit easier on vertical surfaces.
Di-electric grease for the o-ring. Also optional. helps to avoid ruining seals/orings during install

Tools needed:
3/8 ratchet
couple of 3/8's extensions (I used a 3" and 6")
10 mm socket
10 mm combo wrench
12 mm (I can't recall off the top of my head on this)
13 mm combo wrench
14mm combo wrench
14mm socket
18mm socket or combo wrench (alternator tensioner)
Flat head screw driver

Special Note: Most of the small bolts in this job are going into aluminum, aluminum is soft and likes to strip (if you have a leaking valve cover you're probably ware of this). Double check the torque specs on these bolts before going to town on them with your favorite ratchet.
  • Disconnect battery, you'll be working around the alternator.
  • disconnect AFM electrical connector
  • remove vacuum hose idle air controller to AFM/TB tube
  • use flat head to loosen clamp on tube to Throttle body
  • loosed 2x 10mm nuts on air box
  • remove air box from car

You'll now be looking at the Alternator and the filter housing with much more clarity. The alternator sits in a bracket bolted to the block.
  1. Loosen alternator belt the tensioner mechanism won't need to be removed
  2. Remove alternator belt from alternator
  3. remove upper bolt from alternator to bracket, I believe this was a 14mm. Only 1 wrench is required for this guy and it goes through a couple of rubber bushings.
  4. disconnect the top (2) alternator cables. there are 3 cables. 2 at the top and easily visible. One is a 10 mm, the bigger one is a 12 or 13mm IIRC.
  5. The bottom alternator ground cable should be visible, this is also a 10mm, bolt. Remove the cable.

    For steps 4 & 5 I put the bolts back in ones the alternator/cables were removed to avoid losing any bits
  6. remove bottom / pivot bolt from alternator. This is backed with a 14mm nut so a wrench and a ratchet will be needed. Both are 14mm.

    The alternator may be a bit of a bastard to remove. I pried it out with a hammer handle between the bracket and the alternator.

You should now see this,sans red circles:

These are all 14mm bolts. The top left one is obscured by a bushing that needs to be pushed out (I used a busted flat head and tapped it with a hammer)
  • Remove the 10 mm bolt holding the dipstick tube to this bracket (it's on the front as viewed from the front of the car).
  • Remove the 4x 14mm bolts from the alternator bracket and remove it.
  • Remove the 6x10mm bolts holding the oil filter housing in place. The top 2 bolts are longer than the rest. Keep this in mind for later.
  • Remove the oil filter housing

Here is what you'll now have...

1 oil filter housing the top round bit is where the o ring will go. With all the years on your current engine it'll problem be flatter than a pancake.

Block View

Here is the oil seal that was causing my leak, you'll notice it wasn't providing much of a seal.

When I tried to pry it out with a thin screw driver it did this

  • Clean both surfaces of the block and oil housing thuroughly.
  • If you chose to use it, spray copper gasket sealer on both sides of gasket, give about a minute to tack and place on filter housing. THIS ONLY GOES ON 1 WAY SO PAY ATTENTION!
  • put di-electric grease (again, optional) on the o-ring and slip on to groove in oil filter housing.
  • I chose to put the top 2 bolts in to the housing then line up housing to block. I got a couple of threads on and then put the other bolts. Torque spec I believe is 10nm for these guys. I checked all 6 several times to make sure nothing flexed in an odd fashion.
  • the rest is reverse of assembly. I chose to clean the terminals and connectors on my alternator wiring as it became pretty gunked up from the leak before I put it all back together.

Put it all back together, your biggest hassle will be getting the alternator back in place. Oddly enough the large bottom bolt was easier to get re-installed and lined up before the smaller top bolt could.
Mostly because you could get it through then fit the nut on, the top bolt you have to find the first threads of the welded nut on the bracket.

Lastly when you go to start your car, have plenty of light and watch for leaks, gushers. This is all the more reason you want the area cleaned up before hand.

All in all, it was a lot bigger worry than it had to be. I we prepping to lose a day and have to drive my other car. I had the whole job done in under 2 hours.

Hope this helps. The last guide I found lacked pictures but was very helpful. I figured I'd add some pics.
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Old 01-09-2014, 09:10 AM   #2
kung fu jesus
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Nice work, Dustin!
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Old 04-20-2014, 09:41 PM   #3
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E30: 91 318i
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Thanks as well. A garage wanted $360 to do this. The biggest hassle was getting the old gasket off -- it seemed to be welded on. Once that tedious part was done, I went a slightly different way and used ultra gray RTV sealant on the block and on the housing, sandwiching the new gasket between them.

While I was in there, I changed the dipstick/dipstick tube o-rings, oil pressure sensor, and put in new alternator bushings. The bottom bushings pressed in by hand, while I pounded one of the upper bushings with a dead blow hammer, and used some dish soap and a pair of channel lock pliers to press the other one in.
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Old 08-01-2015, 08:15 PM   #4
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E30: 1991 318iS
Location: Vancouver
Join Date: Mar 2015
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Any suggestions on removing the ring terminals attached to the back of the alternator?

The smaller one is sandwiched between two nuts and when I spin the outer one the inside one spins as well causing the ring terminal to spin pulling on the wire. There isn't enough room for me to fit a small wrench in there either.

The bigger one seems to be held in by only 1 nut but I can't get a clear view but I have the same issue as well it will spin the terminal pulling on the wire.
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Old 08-01-2015, 08:20 PM   #5
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E30: 90 325i
Location: Vegas
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You could fab a thinner wrench out of sheet metal...or grind down an old wrench so it's thinner
1990 Flachalpinweiß 335i
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Old 08-01-2015, 11:49 PM   #6
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E30: 1991 318iS
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Never mind all good managed to get them off, ended up breaking the smaller ring terminal though, but thats an easy fix. Would extending the bigger wire be hard? Just asking cause I was scared of breaking the terminal on the bigger one and the wire wouldn't be long enough to re-attach.
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