Possible warped oil pan

[H.J. 1981]

Hey guys,

Just wish to have some second opinions here, since i am at a loss.

Since i picked up my E30 in January 2019, i had to fight against the car, due to incompetence from the workshop the PO had the car repaired and serviced.

Right now, i am suffering from a leaking oil pan. It is leaking from the rear passenger side corner, a couple of inches (or more) from the rear crank seal carrier (that part is dry).

I have replaced the oil pan gasket 8 times now, i used all sorts of sealants, dry, cork gasket, paper gaskets etc, even new pan bolts and it is still leaking.

I fear that the pan may not be flat in that area, the PO did explain that the engine overheated due to to a cracked head (which itself i had to redo due to the shops incompetence), which makes me believe that the pan probably took some heat damage (since it is aluminium) from the excess heat.

I also tried all sorts of tightening procedures, with and without a torque wrench, no go.

My only alternative now is to replace the actual oil pan. New ones from the dealership are going for €350, aftermarket ones are €150, used ones are €250.

I am leaning towards an original €350 one, but i am not exactly 100% sure if it is worth the money.

I need your advice on what to do next, how does one proceed from this experience? try to get the pan machines flat? could it be that there is a hairline crack that i can not see? should i just drop the €350 and get a new BMW Pan?

Thank you in advanced.

[superj]

i have no idea to help you here. i have never heard of this happening to an oil pan.

my only oil pan replacement experience didn't go well because i bought the wrong aftermarket one and had to just trim the baffling to make it clear the crank throws and oil pump pick up tube.

i guess i would start with the least expensive one and if its no good, return and work my way upwards in price till one is good.

and i hope its not the block is messed up on the bottom

[H.J. 1981]

i have no idea to help you here. i have never heard of this happening to an oil pan.

my only oil pan replacement experience didn't go well because i bought the wrong aftermarket one and had to just trim the baffling to make it clear the crank throws and oil pump pick up tube.

i guess i would start with the least expensive one and if its no good, return and work my way upwards in price till one is good.

and i hope its not the block is messed up on the bottom

Well, i am trying to find out why it is constantly leaking from that corner.

Here is a random oil pan picture, i marked in pink where the leak is coming from, as you can tell it is not from the rear seal carrier.

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Is it possible, that i am torquing the transmission cover bolts too tight? the 4 13mm M8 bolts are 22NM and the E10 torx are also 22NM, the big E12 torx is 41NM or so. Maybe the carrier/cover is adding pressure in that spot?

[superj]

Maybe?

[H.J. 1981]

Just checked the torque specs, i am bang on where the cover bolts should be.

I need to investigate this a lot deeper, i am just not sure where to start. Maybe there is something incorrect with the drive line causing vibrations, the pan bolts are almost always coming loose as well (just a bit).
Could be centre support bearing, axles or diff mount. I know there is some small play in the axles (unsure if it is the CV joints or the axles). Support bearing was done by the incompetent shop, maybe i should give that a check as well (all their work has been seriously shit honestly).

[Mikealwa]

I feel like drive line vibrations would present in other symptoms first? If it was me I'd buy a new oil pan and maybe dab a little loctite on the offending bolts and cross my fingers. That's probably not the smartest approach 😶. They say start with the simplest thing first when troubleshooting, but that doesn't take I to account costs.

[digger]

There are some possibilities:
• oil pan is cracked;
• the oil pan surface is not flat (check it on a precision flat surface);
• the surface of the block is not flat or has surface imperfections;
• It is leaking at the junction of the rear seal cover/block/oil pan;
• gaskets you are using are junk;
• the sealant you are using is incorrect;
• poor technique for application of sealant and cleanliness/prep.

[H.J. 1981]

I feel like drive line vibrations would present in other symptoms first? If it was me I'd buy a new oil pan and maybe dab a little loctite on the offending bolts and cross my fingers. That's probably not the smartest approach . They say start with the simplest thing first when troubleshooting, but that doesn't take I to account costs.

I am inclined to do so.

There are some possibilities:
• oil pan is cracked;
• the oil pan surface is not flat (check it on a precision flat surface);
• the surface of the block is not flat or has surface imperfections;
• It is leaking at the junction of the rear seal cover/block/oil pan;
• gaskets you are using are junk;
• the sealant you are using is incorrect;
• poor technique for application of sealant and cleanliness/prep.

If there is a crack, it would most likely be at that corner bolt, hairline crack that i never noticed before.

Pan surface is not flat is what i am leaning towards the most.

Block surface not flat, only way to check is to use a straight edge, can do that when the pan is off.

I am very certain it is not from the rear seal cover, as you can see from the picture i linked above, it is leaking well in front of the area.

I used elring cork gasket, then febi, then AJUSA paper gasket, i tried no gasket and just sealant, then a whole combination of RTV, Anaerobic sealant, Hylomar M etc etc

I always made sure everything was clean and dry, tried applying the gasket onto the block, then on the pan and so forth. It never leaks from the front or rear seal carrier(s).

I guess i need to remove the pan again and check, but as i stated i am unsure where to go from there. In case there is indeed a crack or if the pan is not flat, should i prepare by getting an OE Pan from the dealership or go aftermarket for testing purposes.

[msservices]

After the 3rd or 4th time replacing the oil pan gasket it would become clear that it’s not the oil pan gasket leaking. Time to pressure test the motor. Plug the exhaust with wadded up plastic bags, with a little tape to keep them in, then remove the AFM and rubber boot from the throttle body, go get yourself a rubber coupler from a big box/hardware store plumbing department, I believe you can stretch a 2” over the throttle body. These couplers have band/ hose clamps that allow you to connect them to other plumbing fittings. Then reduce with pvc until you can install a small ball valve and a air fitting which will allow you to pressurize (low psi here) and then close the ball valve so your compressor doesn’t have to run while you are performing this test. Get some soapy water and a spray bottle. Let us know what you find. Now If all this seems like too much work, or the “I’m not a plumber” mindset kicks in, just know that this apparatus does not cost much, and has helped me find all sorts of leaks/issues. It is basically the same concept as a smoke test only using enough air pressure to overcome the fluid friction between the leaking gaskets.Also this test will help you find the leak BEFORE you fill the engine with oil and go driving it around while trying to look under it at the same time. Now if you haven’t been using a RTV/gasket sealer on both sides of your oil pan AND valve cover gasket, then that’s most likely the issue but I’m sure you have already done both as well as those pesky black rubber plugs that sit below the valve cover gasket

[Twright]

Send us close up pictures of the oil pan and block surfaces at the leak location. Scratches or corrosion could cause leaks in this area.

How much of a leak are you experiencing? Is it dripping off of the oil pan?

[H.J. 1981]

The leak is more like a small trickle of oil, it does not really effect the oil level between services. More like 0.1 liters /around 0.12 quarts) of oil loss in total.

I shall be tackling this in end of this week or next week, im busy moving 200kms (around 140 miles) away and need to prioritise things.

Will be sending pictures off course.

Valve cover as well as the plugs are bone dry, first thing i checked.

With the gearbox reinforcement plate off, everything is bone dry behind the flywheel (one can squeeze a rag to touch the block and see if it is dry or wet).

[H.J. 1981]

Okay, this is what i am going to do.

I shall pick up an engine oil UV dye, since i already have the UV light and glasses from my AC leak tester kit. That way, i can detect exactly where the oil leak is coming from.

I shall also be rebuilding the drive shaft (front guide bushing, guibo, centre support bearing + dust shields) it is something i wanted to do ever since i got the car, just a nagging feeling that the PO shop screwed something up.

I shall take pictures of everything and update you guys here, and we shall take it from there.

[msservices]

No thoughts on the air pressure test?

[H.J. 1981]

No thoughts on the air pressure test?

I really want to, but i would need to check with the DIY shop first for using their system and hooking it up for pressure testing the engine for leaks. Since i am in the middle of moving, i shall start with the quickest/easiest method first. If that does not work, then i shall pressure test the system.

[H.J. 1981]

Small update:

Managed to use the engine oil UV dye, drove the car for 30 minutes and did a quick inspection.

The front end of the car is bone dry and no indication of a leak.

Valve cover is also bone dry, front to back and no indication of a leak.

Best i can do now is check the rear of the engine, the last visible oil pan bolt before the reinforcement cover, the top of the bolt ( when looking from the engine bay, it is the bottom of the threads) shines under UV light. Which indicates that oil is getting past the bolt and threads for starters.

The bottom rear "belly pan" behind the engine is glowing under UV light. So indeed the only oil leak is from the rear/side of the engine. Tomorrow i shall try to squeeze a 1 hour session at the DIY workshop and get the car on a lift, remove the belly pan and reinforcement plate and check exactly where the leak is coming from.

I suspect the rear main seal is fine and it is either a warped/hairline cracked pan or oil getting past the bolts. Worse case the block is warped i guess.

Any ideas on how much gap to measure with a feeler gauge for the block/pan? 0.15mm?

[H.J. 1981]

Good news, i think.

The leak is surely from the corner side of the pan, UV light and dye did the job.

Pics show how the oil leaked past the gasket, every other area of the engine is bone dry and has no leaks.

The tissue shows how the entire area behind the flywheel (where the rear crankshaft seal sits on the carrier) is bone dry.

So this means, either the pan is warped, the block is warped or the drive-train is causing enough vibrations to loosen the bolts. All the pan bolts were a bit loose, so i torqued them all to 10NM, those two bolts on the pan i torqued them to 14NM, since 12NM barely moved the bolts, a smidge more just to see if it would make any difference.

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I am rebuilding the drive shaft completely first, since the vibrations are obvious, then check the bolts/pan and take it from there.

[msservices]

I missed the part about whether or not you used a sealer on both sides of the gasket.

[H.J. 1981]

I missed the part about whether or not you used a sealer on both sides of the gasket.

This last time i replaced the oil pan gasket, yes i am using a paper gasket (Brand AJ USA that the dealership sells) along with Reinzoil 300 from Victor Reinz. A small paper thin "skin" of sealant on the block and the oil pan, basically "sandwiching" the gasket, just enough to hold the gasket onto the block/pan, nothing crazy.

I did try cork and paper previously dry, with Hylomar M, Elring Dikro, only one side etc etc with the same results.

[aaverhulst]

I would think cork would be best as it's thicker and more compressible. Real mystery why that area doesn't seal - has to be a reason.

[msservices]

I would not use paper. I would use the cork and use a small bead of gasket sealer on both sides and drawer a circle around the bolt holes with the bead. Also they say to tighten the bolts by hand until the gasket sealer sets, then torque them a day later

[H.J. 1981]

I would think cork would be best as it's thicker and more compressible. Real mystery why that area doesn't seal - has to be a reason.

From what i have learned, the cork gasket is 1mm thick (uncompressed) and gets much thinner when compressed. I did experience the cork gasket "slipping" the first time i did the pan gasket, when the sealer was still wet. The paper gasket is 2mm thick uncompressed.

As i mentioned, either the pan is not flat, the block is not flat (for that area) or the drive train vibrations are causing the bolts to come loose.

I would not use paper. I would use the cork and use a small bead of gasket sealer on both sides and drawer a circle around the bolt holes with the bead. Also they say to tighten the bolts by hand until the gasket sealer sets, then torque them a day later

I tried that before and same results, i even tried no gasket and just a sealer, similar to the iX models (they do not require a pan gasket) and it still leaks.

I should rebuild the entire drive train this week, hopefully it is either the CSB or the Guibo that is shot and stops the vibrations before i continue investigating the pan issue.

[H.J. 1981]

Wanted to give an update, it appears that the driveshaft and rear axles were indeed the cause of vibrations.

I found the driveshaft both halves to be aligned incorrectly, both white dots were about 15 degrees off. So i went ahead and rebuilt it, using a new guibo, new center bearing (and both dust shields, which are expensive from BMW, ordered them as a pre-caution and one was missing), new snap ring, new sleeve (that big nut + inner washer and rubber piece), new front driveshaft bushing and all new hardware (self locking nuts and bolts). 90% of the vibrations went away, so i bit my lip and spent more money on new/rebuilt rear driveshafts. Apparently there is an issue with companies such as GSP and SKF. Where GSP fits perfectly they fail very quickly (months) and not recommended, SKF suffers from fitment issues, from ABS ring teeth being incorrect, to sometimes being too long/too short or different end flanges (does not match the differential). So i got SPIDAN/GKN rebuilt ones with no core. Fitment was spot on, but one shaft used the standard nut, the other had those 12 point ones. Anyways new shafts are in, also got new injectors since one (or more) were acting up.

Did a nice test drive today, all the way up to 200kph (around 125-130mph) on the autobahn and nothing. No vibrations when accelerating, light throttle or off throttle. Despite it being very windy, car felt solid and planted with full confidence (finally).

I am doing some more work, water pump is making a noise when cold (and now slowly when warm) so a new belt and pump are going in. I MIGHT change the shocks/dampers to Monroe, since the B4s are just too damn harsh on the broken ass roads i have here (M-tech suspension + factory beefy sway bars + broken roads is just a horrible combo). If i do get new damper/shocks, i might change the pan gasket one last time. At least then, i would know that vibrations are no longer a role in why the pan keeps leaking (i will measure the pan and block mating surfaces as well) from there, i can definitively say, if it was vibrations or indeed a slight warp in the pan/block.

Note: The original e30 driveshafts are going up in price on the used market due to the reasons i stated above. If you have the chance to hold onto your original shafts, or have someone actually rebuild them and send them back (new CV joints as well, not just grease and boots) then do so.