e92 rear main seal/crankshaft gasket, help

soulcrusher · 02-18-2020, 11:36 AM

Hi. I am finishing the replacement of my oil pan gasket at home for an 07' automatic 335i. My eyes saw oil pooled to the rear of the oil pan at a rubber seal below the transmission. The sensors that are mounted at this junction between/below the oil pan and transmission were also dirty with dry old oil. My concern is for an overlooked rear main seal leak/rear crankshaft seal leak!

For peace of mind how do I rule out a rear main seal leak. Or has anyone posted a DIY? I am searching online for more information but its limited. Need help.

In comparison to dropping the oil pan, is replacing the RMS a recommended DIY procedure? I already have the subframe dropped. I keep reading that special tools are needed for a RMS gasket replacement. If I can rule out a leak at the RMS then I can avoid all this.

[Update 2:19PM] Checked out the repair manual on newTIS for removing the transmission. The directions are confusing.
https://www.newtis.info/tisv2/a/en/e...rings/Fr4lqrAD

Oolien · 02-19-2020, 12:48 AM

as far as i have been told to test for rear main leak, is to remove that plastic cap and put your finger in and if there is oil there is then its rear main. dont know the truth to it but thats what i have been told..

mweisdorfer · 02-19-2020, 12:20 PM

What's the PCV situation? When's the last time the PCV hose & valve been changed? If that's failed, it's causing excess pressure in the in the crank case. This will cause a VC leak & an RMS leak.

Yes, you need a special tool to remove and put in a new seal. You can rent this tool or buy it. You also need gasket sealer. I'd use Ultra Grey. The BMW sealant is very expensive, and it doesn't even come with the needle, unless you order it in a kit or buy it separately. Even so, you'll end up breaking your fingers or any plunger you buy (the bmw syringe doesn't even come with a plunger!!!) just trying to get a few drops out. Ultra Grey is specifically made for crank seals etc.; it does however take 24 hours to cure.

I think I'd change the oil pan gasket and sandwhich the OEM gasket in between two beads of Ultra Black. If you still have oil in that area, it's most definitely the RMS. There's no harm in changing the oil pan gasket. It's gonna leak eventually.

You don't need to take the subframe out to change the RMS. Maybe drop it a little, but that's it.

juld0zer · 03-14-2020, 05:03 AM

Historically, engine sump gaskets leak far more frequently than rear main seals. By the time people attend to a leaking sump gasket, it looks like a rear main seal especially if the oil filter housing or rocker cover gaskets are also leaking.

Replacing the rear main seal is definitely not a might aswell or while you're at it sort of job and having the subframe down is of no benefit. If anything it is more difficult to remove the transmission as the engine is no longer steady in its cradle

02-18-2020, 11:36 AM	#1
soulcrusher Private 9 Rep 63 Posts Drives: BMW 335i Join Date: Nov 2019 Location: Miami iTrader: (0)	e92 rear main seal/crankshaft gasket, help Hi. I am finishing the replacement of my oil pan gasket at home for an 07' automatic 335i. My eyes saw oil pooled to the rear of the oil pan at a rubber seal below the transmission. The sensors that are mounted at this junction between/below the oil pan and transmission were also dirty with dry old oil. My concern is for an overlooked rear main seal leak/rear crankshaft seal leak! For peace of mind how do I rule out a rear main seal leak. Or has anyone posted a DIY? I am searching online for more information but its limited. Need help. In comparison to dropping the oil pan, is replacing the RMS a recommended DIY procedure? I already have the subframe dropped. I keep reading that special tools are needed for a RMS gasket replacement. If I can rule out a leak at the RMS then I can avoid all this. [Update 2:19PM] Checked out the repair manual on newTIS for removing the transmission. The directions are confusing. https://www.newtis.info/tisv2/a/en/e...rings/Fr4lqrAD Last edited by soulcrusher; 02-18-2020 at 01:22 PM..
	Appreciate 0 Tweet Quote

02-19-2020, 12:48 AM	#2
Oolien Enlisted Member 3 Rep 47 Posts Drives: 08 bmw 335xi n54 Join Date: Apr 2019 Location: canada iTrader: (0)	as far as i have been told to test for rear main leak, is to remove that plastic cap and put your finger in and if there is oil there is then its rear main. dont know the truth to it but thats what i have been told..
	Appreciate 0 Quote

02-19-2020, 12:20 PM	#3
mweisdorfer Major General 1903 Rep 6,968 Posts Drives: 2007 Black/Black 335i e90 Join Date: Apr 2011 Location: Holly, MI iTrader: (0) Garage List 2007 BMW E90 335i [0.00] 2008 bmw x5 [0.00]	What's the PCV situation? When's the last time the PCV hose & valve been changed? If that's failed, it's causing excess pressure in the in the crank case. This will cause a VC leak & an RMS leak. Yes, you need a special tool to remove and put in a new seal. You can rent this tool or buy it. You also need gasket sealer. I'd use Ultra Grey. The BMW sealant is very expensive, and it doesn't even come with the needle, unless you order it in a kit or buy it separately. Even so, you'll end up breaking your fingers or any plunger you buy (the bmw syringe doesn't even come with a plunger!!!) just trying to get a few drops out. Ultra Grey is specifically made for crank seals etc.; it does however take 24 hours to cure. I think I'd change the oil pan gasket and sandwhich the OEM gasket in between two beads of Ultra Black. If you still have oil in that area, it's most definitely the RMS. There's no harm in changing the oil pan gasket. It's gonna leak eventually. You don't need to take the subframe out to change the RMS. Maybe drop it a little, but that's it.
	Appreciate 0 Quote

03-14-2020, 05:03 AM	#4
juld0zer Lieutenant Colonel 480 Rep 1,600 Posts Drives: Prev 135i 7DCT, Now 130i 6sp Join Date: Jul 2016 Location: 2153 iTrader: (0)	Historically, engine sump gaskets leak far more frequently than rear main seals. By the time people attend to a leaking sump gasket, it looks like a rear main seal especially if the oil filter housing or rocker cover gaskets are also leaking. Replacing the rear main seal is definitely not a might aswell or while you're at it sort of job and having the subframe down is of no benefit. If anything it is more difficult to remove the transmission as the engine is no longer steady in its cradle
	Appreciate 0 Quote