M30 oil pan removal...calling Hector and George M

[Robert K]

Well, I will most likely be lifting the engine in my 1991 535i tomorrow to attempt to remove the oil pan. Over the years, I always snugged up the pan bolts when I had it up and it looks like the gasket right at the front has "squirted" out enough that it's leaking terribly. I spent today taking pieces off and loosening others per Bentley and other posts from the board. But before attempting to lift the engine, I have a couple of questions.

1. Is it necessary to completely remove the nuts that connect the middle exhaust to the headers? I have the nuts backed all the way to the end of the threads right now so the exhaust is still loosely connected to the headers.

2. When I get ready to raise the engine, will I be able to use a single jack with the lifting head positioned against the oil pan, or will I need two jacks? Also, if I can use one jack, exactly where does it need to be positioned to evenly lift the engine? Does the aluminum oil pan really take the weight of the engine? For that matter, when I get ready to lower the engine back onto the mounts, will all the engine's weight on the new pan gasket cause problems for it once again?

3. Will I only need to drop the oil pump in the pan to be able to slide the pan out?

I think that's all the questions I have for now. I've searched the archives and read about every post on this job. It doesn't sound like much fun. But the huge oil leak I have isn't much fun either, so I'm going to just get it done. After that, I just need to figure out what's causing the slight miss at highway speeds and I'll have my car in great shape. Of course that would be a great time to sell it and buy a Honda or Toyota or something that didn't need fixing all the time. Just kidding...sort of. That Infinity G35 sure would be nice....


Grace and peace,

Robert K
1991 535i

[George M]

Hi Robert,
Well...I give you credit for tackling it...one of the least fun jobs to take on for these cars.
Ans:
1. You are fine...most only loosen the downstanding flange exhaust bracket where it ties to the trans mounts as the exhaust connection to the manifold is spherical. Robert, I would loosen the trans mounts as well as that is where the drive train will fulcrum when you raise the front of the engine.

2. If you push up with a floor jack you can block each side at the engine mounts with wooden shims. You can do this with or without removing the puck mounts themselves....I like it with the mounts removed. The easiest way is with an engine lift up top as you don't need the shims...and don't have to remove the hood since it pivots from the front of the car. As to lifting...if you notice the engine because it is canted or layed over 30 degrees is not symmetric x-car in terms of distance from each mount for equivalent lifting on each side from the centerline of the pan. Using a generous block of wood...I suggest a 2 X 6, bias the wood block to the left side of the pan for more uniform lifting of the engine X-car if pushing up from the bottom.

3. Two approachs really...either disconnect the whole pump and sprocket and drop it in the pan or just unbolt the lower pick up because that is what interferes with the internal pan baffle when trying to push it off with the cross-member in place.

Lastly, to keep your frustration quotient low :-), I would give yourself a generous time window..it is a difficult and messy job particularly on your back without a lift and if you decide to shim the motor up and not elevate it with a cherry picker.

Check around the engine to make sure there aren't any other interfering areas...like hydraulic hoses...AC hose clamp down to the body on the pass side etc.
Good Luck,
George

[winfred]

how i do it, remove ether the fan or shroud for clearence, unbolt motor mounts and jack up motor and insert a 4" block of wood under edge of each motor mount, remove all pan bolts and lower pan then remove oil pump and place in pan, then pull the pan out (you may need to rotate the crankshaft, sometimes one of the connecting rods will hang down in the way) on installation locktight the nut on the oil pump sprocket (i had one come loose once and fall off)

[Hector]

for this pain in the butt job.

1. If I recall correctly, the studs on the exhaust manifold are threaded to mid length so you may have to take the nuts completely off or else this may put a limit on how high you can raise the engine. You should get at least 2" of clearance between the bottom of the engine mount bracket and the top of engine mount puck when you lift the engine. I agree with George, loosen the tranny nuts from their mounts as much as you can but don't take them off.

2. I can see why you would prefer to use 1 floor jack but personally, I wouldn't lift the engine by positioning a floor jack against the oil pan. The oil pan may be quite sturdy but I wouldn't wanna run the risk of denting it... If we considered for a moment that you were successful in replacing the gasket with 1 floor jack against the pan, then after lowering the engine (assuming the jack head is somewhere against the front of the pan,) I think the weight of the engine would cause the cheap cork gasket to ooze out from the front of the oil pan. Man, don't risk it unless someone else here on the board chimes in on this method. Remember to get the paper gasket.

What I did was I bought 2 cheap 1-ton floor jacks from Wal-Mart, about 8 to $10 apiece and from positioning one against the AC compressor and the other against the power steering pump was able to lift the engine evenly. This technique was suggested by Martin. Then I dropped the x-member on the passenger side while keeping the driver side loosely bolted. Also, had to loosen the rear stablizer bar (it connects to each side of the subframe with 3 bolts per side) to allow the x-member on the passenger side to drop a bit more. If you use this technique, you will need a jack to raise the x-mbr on the passenger side and make sure the dowel pin in the x-mbr goes back into its mating hole in the subframe when it comes time to bolt the x-mbr back on. If front-end misalignment is introduced, I would expect it to be minimal. Can't see why this would be an issue when the appropriate suspension components that have been dropped/loosen fit back in their place nicely. I haven't driven the car to check for this yet. I believe the mechanic I go to from time-to-time uses the drop-the-x-mbr method to change the gasket.

3. To drop the oil pump in the pan the engine has to be raised as high as possible otherwise you will have a hard time getting the pump out. The trick is to first loosen the sprocket nut and slightly dislodge the sprocket from the oil pump shaft. Then remove the oil pump bolts, jiggle and twist the pump to pull the sprocket off, and the pump is free. Make sure not to gouge the engine block mating surface when doing this.

HTW

[Robert K]

I did already have the trans mount bolts loosened and also have removed the A/C hose hold down clamp bolt. I've also loosened or removed everything that has been mentioned either here on the board or in Bentley. I feel that I'm ready to raise it up tonight when I get off work.

Probably my two biggest concerns were lifting against the aluminum oil pan and possibly crushing the new gasket when I put the weight of the engine on it to lower the engine back in place. I suppose others here have lifted the engine by the pan and never had any problems cracking it. I hope I have the same success. I would rather not have to track down a cherry picker if possible. That just adds another element and delay to the job.

As far as the time, I'm not in too big a hurry. I just want to stay with it and get it done. Like I said, after this gets done, I've got to chase down an intermittent miss. At that point, the car should be in about perfect working order.

I'll let you all know when I get it done.

Regards,

Robert K
1991 535i

[Robert K]

Hector, thanks for the follow up. I am following the advice you gave me when we last spoke. I have to admit that I don't quite understand how you lifted against the power steering pump. To get to some of the pan bolts, the power steering pump has to come off. I've already got it removed and hanging from a wire. When you did yours, did you first lift the engine and get it supported with blocks under the engine mounts, THEN remove the power steering pump??? And if I remember correctly, the main support for the power steering pump is an extension off of the oil pan. I realize it's not the flat portion of the pan, but it's still a part of the pan. It seems like you end up still lifting by the oil pan even if you jack off of the power steering pump. If I can figure it out, I may try to lift against the motor mount brackets themselves. I'll just have to take a look at it when I get home. Anyway, thanks again for taking the time to tell me how you did it. Hopefully, I'll be past this in a couple of days. I already look forward to it! :)

Grace and peace,

Robert K
1991 535i

[Martin in Bellevue]

The power steering pump was unbolted & swung out of the way. I left the big floor jack under the compressor bracket. Do check the bracket bolts before all this.
I'd suggest getting the napa paper gasket over the stock cork piece.

[Hector]

floor jacks under the AC compressor and power steering pump. It really works!! You have to disconnect the belt from the PS pump and swing the pump up and to the right (as you face the front of the car) so that the pump is out of the way. No need to remove pump. I jacked up the engine using the AC/PS pump jack points 4 times for various reasons (long story) so I know this well. Tonight I'll try to take a picture of how I had this setup. Maybe a pic will make a bit more sense. I didn't use wooden blocks, I kept the engine jacked up all along during the job.
HTW

[Hector]

The right floor jack was actually replaced by the jack of my Mazda. This jack had a slot in the middle of the head so that I could wedge it right under the bolt carriage (indicated by red arrow) in the power steering pump for a more secure fit.

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HTW