BMWSportTouring

Press depth of new rear main seal

Posted By: dduelin

Press depth of new rear main seal - 11/13/17 01:51 AM

I'm going to replace the rear main and the balance shaft seals while the engine and gearbox are separated. The Haynes manual details pressing the new main seal in until it is flush with the outer edge of the seal housing in the block. However the original seal is pressed in beyond that to a recessed depth of ~ 4.2 mm from the edge of the housing. I would think it is best to place the wiping edge of the new seal in the same spot on the crankshaft as the old one? Or should I follow instructions and install it to flush with the housing edge?
Posted By: dirtrider

Re: Press depth of new rear main seal - 11/13/17 01:10 PM

Originally Posted by dduelin
I'm going to replace the rear main and the balance shaft seals while the engine and gearbox are separated. The Haynes manual details pressing the new main seal in until it is flush with the outer edge of the seal housing in the block. However the original seal is pressed in beyond that to a recessed depth of ~ 4.2 mm from the edge of the housing. I would think it is best to place the wiping edge of the new seal in the same spot on the crankshaft as the old one? Or should I follow instructions and install it to flush with the housing edge?


Morning Dave

On the 1200 rear main seals that I have installed (only a few) they were originally pressed in below flush. I never measured the depth as I used the (special) flanged BMW seal driver & bushing to install the new seals. That special BMW driver drives the seal to well below flush (that 4.2mm would be a good guess, but as I mentioned, I never measured it).

I can't remember if there is an oil drain back hole in front of that main seal but if there is then make darn sure your new seal doesn't block any oil holes.

The only time I would mess with a seal depth change is if there is a worn ring on the crankshaft, if you do change the seal depth, then as mentioned above, make sure that you are not blocking an oil drain-back hole or that the seal will contact a spinning flywheel bolted to rear of crankshaft.
Posted By: dduelin

Re: Press depth of new rear main seal - 11/13/17 04:41 PM

Thanks D.R. I posted that because the Haynes does show the BMW special tool set installing that seal and mentions a flush set. The BMW tool and how to use them (guide, sleeve, and driver) are shown in the pictures. Mine is clearly set deeper however. It's been fine for 189,000 miles so I'll try to reset to the same approximate depth. I'm using a DIY seal guide and driver that another owner used to install this seal 90,000 miles ago on his 1200.
Posted By: dirtrider

Re: Press depth of new rear main seal - 11/13/17 06:15 PM

Originally Posted by dduelin
Thanks D.R. I posted that because the Haynes does show the BMW special tool set installing that seal and mentions a flush set. The BMW tool and how to use them (guide, sleeve, and driver) are shown in the pictures. Mine is clearly set deeper however. It's been fine for 189,000 miles so I'll try to reset to the same approximate depth. I'm using a DIY seal guide and driver that another owner used to install this seal 90,000 miles ago on his 1200.


Afternoon dduelin

If you look closely to the BMW 1200 rear driver set you will see that the flange on the intermediate collar is the thickness of the seal recession. The DRIVER TOOL is driven flush but that drives the seal in farther due to the intermediate collar thickness.


[Linked Image]
Posted By: dduelin

Re: Press depth of new rear main seal - 11/14/17 03:17 AM

Thanks. Although the Haynes lists these three part numbers to use, the text and pictures indicate to press the seal flush. Mine is clearly not flush but like your posted drawing. I will do likewise. The drawing indicates the seal does seat against a small ledge or land. I suppose it will be clearer when the old seal is out.
Posted By: bwpsg42

Re: Press depth of new rear main seal - 11/14/17 07:20 PM

I understand better what we were talking about at Breakfast Sunday. Good luck with the repair, nice meeting you.
Bill
Posted By: dduelin

Re: Press depth of new rear main seal - 11/15/17 02:28 PM

Nice to meet you as well Bill.
Posted By: dduelin

Re: Press depth of new rear main seal - 11/15/17 02:32 PM

My angst was misplaced. The engine block is machined so that the rear main seal can only be set so deep and the DIY tool I was using also had the inner bore turned in a lath or something so it could only press the seal in so far. Both the new compensating shaft and main oil seals are in place and the process of putting everything back together has started.
Posted By: Matts_12GS

Re: Press depth of new rear main seal - 11/21/17 04:42 PM

Quick question... Is this the same for the front main seal? I'm contemplating doing mine this winter to remove a slight weep.
Posted By: lawnchairboy

Re: Press depth of new rear main seal - 11/21/17 04:46 PM

blew a seal?

grin
Posted By: Matts_12GS

Re: Press depth of new rear main seal - 11/21/17 08:33 PM

Originally Posted by lawnchairboy
blew a seal?

grin


leave my personal life out it and just fix the damn thing...

<h/t> Kip Adotta
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