Please Help! Rear Main Seal Replacement Tonight

Ol'Rattler · Nov 3, 2010

I should qualify my statements with the fact that I have never actually changed the seal/tone ring. A5INKY, so far is the only person I have heard of that has.

I just revisited the procedure in the Bentleys CD and I don't think cam position or T/B stretch are relevant. If you get the tone ring wrong, no amount of cam to crank adjustment will fix it.

The engine MUST be at TDC on #1 cylinder. This is done with the crankshaft lock tool that you use when doing T/Bs. Once there, the rear main seal tool indexes the tone ring to the crank and is used to sets how far the tone ring is pressed on to the crank.

It does seem reasonable that if you got the new one on in the same exact place and depth, it should work. We just need someone to develop a bullet proof work around.

When I did my clutch, I was going to change the rear main seal, but after reading the procedure, I figured there was way to much potential for fail. I'm sure that if it is off, even a couple of degrees, the car would probably run like crap making it necessary to pull the transaxle once again to fix it.

mnguy · Nov 3, 2010

I was going to do the same, but after pulling off the flywheel and seeing oil dripping from the seal I am kind of screwed. I am going to mark everything really well for depth and the rotation to be safe and then lock in the cam and crank and put the new seal in the freezer overnight to shrink it and give me a little more wiggle room. I will post pics if it works!

DanG144 · Nov 3, 2010

Putting the seal in the freezer will shrink it. Make it tighter on the shaft? Is that what you want? Also it will make the elastomers and plastics more brittle.

Ol'Rattler · Nov 3, 2010

That sucks. Fortunately, on mine, it wasn't leaking.

Don't think freezing the seal will gain you anything. The hole through the middle will shrink a little making it harder to get around the crank plus moisture will condense on it when it hits the air possibly affecting how it seals.

Actually, you only need to lock down the crank, as far as the crank position sensor is concern.

Remove the CPS and get it out of the way before removing the seal assembly. (Bentleys)

With the newer type seals (Teflon?), make sure there is absolutely no oil on the crank and then let it sit for something like 4 hours once installed before turning the crank, or it won't seal properly.

Hope it works out.......................

mnguy · Nov 3, 2010

I was going to do the same, but after pulling off the flywheel and seeing oil dripping from the seal I am kind of screwed. I am going to mark everything really well for depth and the rotation to be safe and then lock in the cam and crank and put the new seal in the freezer overnight to shrink it and give me a little more wiggle room. I will post pics if it works!

mnguy · Nov 20, 2010

mnguy said:
I was going to do the same, but after pulling off the flywheel and seeing oil dripping from the seal I am kind of screwed. I am going to mark everything really well for depth and the rotation to be safe and then lock in the cam and crank and put the new seal in the freezer overnight to shrink it and give me a little more wiggle room. I will post pics if it works!

Well I set everything at tdc and locked the crank and cam, just to be safe since there is a little play in my crank lock, then I dropped the oil pan and marked the crank where the hole is with a marker then used a punch very lightly so I didn't loose my mark. I took a marker and marked how far the metal ring was pressed onto the crank so that the new one would be the same. I took the old seal out, slide the new one on lining everything up and after putting in the new flywheel and clutch and everything else the car fired up and runs like new.

Saiga542 · May 16, 2011

A5INKY said:
It was not worth the risks to me to save $218 dollars. My car is more important to me than that, not to mention the value of my time to have to completely redo the job plus to have to buy another seal/sensor AND the tool anyway.

Just my 2 cents

Nicely said!

Barnitz · Aug 29, 2011

mnguy said:
Well I set everything at tdc and locked the crank and cam, just to be safe since there is a little play in my crank lock, then I dropped the oil pan and marked the crank where the hole is with a marker then used a punch very lightly so I didn't loose my mark. I took a marker and marked how far the metal ring was pressed onto the crank so that the new one would be the same. I took the old seal out, slide the new one on lining everything up and after putting in the new flywheel and clutch and everything else the car fired up and runs like new.

Any pictures of this?

325isbimmer · Jan 31, 2012

Just wanted to add my $0.02 to this thread as it helped me to understand how to replace this seal/sensor without the tool. Although nerve racking (and possibly not worth effort and stress to some) it is possible with some careful planning and precautions.

mnguy said:
Well I set everything at tdc and locked the crank and cam, just to be safe since there is a little play in my crank lock, then I dropped the oil pan and marked the crank where the hole is with a marker then used a punch very lightly so I didn't loose my mark. I took a marker and marked how far the metal ring was pressed onto the crank so that the new one would be the same. I took the old seal out, slide the new one on lining everything up and after putting in the new flywheel and clutch and everything else the car fired up and runs like new.

I did a similar approach. i also marked and measured where the old seal was so that I had some references but I think more importantly I rigged up my own locating and pressing solution. It took some looking at it and researching.
Basically what I did (above locking everything at TDC like previously mentioned) was mount a flat surface to where the oil pan meets the block to act as a timing locator since the ring starts to press on the crankshaft before the bottom portion of the seal reaches the edge of the where the lip of the oil pan would be. Then with the orange plastic ring locator still attached I tapped the ring down so that it would not rotate then the plastic locator can me removed. Next I got some threaded rod (should be M7x1.0 but I found out that with it being unavailable to me at the time I could get away with 1/4-20 threaded rod and still engage 2 or 3 threads finger tight without damaging anything, although I would not condone this unless you know what it feels like to strip out a hole in a cast iron block, and know the risks involved) anyways, I used the existing mounting holes (6) and 3" of thread rod will serve to closely located the new ring. That coupled with the flat plate mounted flush and squarely to the bottom on the block it VERY closely located the new seal. However I still did a double check with me reference measurements to make sure I was in the same spot as the old seal. THEN (and this is where I had eureka moment when trying to figure out what I was going to use as a pressing tool to ensure the ring does not get pressed on too far but is at the correct depth) I used the OLD seal and flipped it around (the holes are symmetrical about CL) and because the old ring will inset about 0.5mm into the plastic casing (that actually houses the Teflon seal part of it, ring is the sensor (transmitter) it will allow the ring of the new seal to have the required stick out on the crankshaft. Then using some nuts on the threaded rods I slowly turned each a half turn as I worked my way around in a star pattern. Insure that you are pressing the seal on square to the block by taking some measurements after making a couple of turns of all the nuts. Slow and methodical is the key to success here.
This resulted in what looked like an identical location to where the old seal was and the engine runs great! (better than it did before but I assume thats due to the camshaft, TB, SMF flywheel and new clutch I installed. Oh, and the VNT stop screw adjustment that took care of the boost surge and hiccup symptoms I was having)
Hope this makes some sense.
I will post a pic shortly that will explain these 1000 or so words...

This image is just after I losely placed the seal over the studs and lined up with the straight edge, Next I took the old seal flipped around and then used nuts on the threaded rod to evenly press the new seal on. Sorry but I didn't take a picture after this stage as I was far more focused on the task at hand. The guide cone that comes pre-installed on the new teflon seal actually presses itself into the old seal when you're done.

James & Son · Nov 14, 2013

325isbimmer said:
Just wanted to add my $0.02 to this thread as it helped me to understand how to replace this seal/sensor without the tool. Although nerve racking (and possibly not worth effort and stress to some) it is possible with some careful planning and precautions.

I did a similar approach. i also marked and measured where the old seal was so that I had some references but I think more importantly I rigged up my own locating and pressing solution. It took some looking at it and researching.
Basically what I did (above locking everything at TDC like previously mentioned) was mount a flat surface to where the oil pan meets the block to act as a timing locator since the ring starts to press on the crankshaft before the bottom portion of the seal reaches the edge of the where the lip of the oil pan would be. Then with the orange plastic ring locator still attached I tapped the ring down so that it would not rotate then the plastic locator can me removed. Next I got some threaded rod (should be M7x1.0 but I found out that with it being unavailable to me at the time I could get away with 1/4-20 threaded rod and still engage 2 or 3 threads finger tight without damaging anything, although I would not condone this unless you know what it feels like to strip out a hole in a cast iron block, and know the risks involved) anyways, I used the existing mounting holes (6) and 3" of thread rod will serve to closely located the new ring. That coupled with the flat plate mounted flush and squarely to the bottom on the block it VERY closely located the new seal. However I still did a double check with me reference measurements to make sure I was in the same spot as the old seal. THEN (and this is where I had eureka moment when trying to figure out what I was going to use as a pressing tool to ensure the ring does not get pressed on too far but is at the correct depth) I used the OLD seal and flipped it around (the holes are symmetrical about CL) and because the old ring will inset about 0.5mm into the plastic casing (that actually houses the Teflon seal part of it, ring is the sensor (transmitter) it will allow the ring of the new seal to have the required stick out on the crankshaft. Then using some nuts on the threaded rods I slowly turned each a half turn as I worked my way around in a star pattern. Insure that you are pressing the seal on square to the block by taking some measurements after making a couple of turns of all the nuts. Slow and methodical is the key to success here.
This resulted in what looked like an identical location to where the old seal was and the engine runs great! (better than it did before but I assume thats due to the camshaft, TB, SMF flywheel and new clutch I installed. Oh, and the VNT stop screw adjustment that took care of the boost surge and hiccup symptoms I was having)
Hope this makes some sense.
I will post a pic shortly that will explain these 1000 or so words...

This image is just after I losely placed the seal over the studs and lined up with the straight edge, Next I took the old seal flipped around and then used nuts on the threaded rod to evenly press the new seal on. Sorry but I didn't take a picture after this stage as I was far more focused on the task at hand. The guide cone that comes pre-installed on the new teflon seal actually presses itself into the old seal when you're done.

I now own GoFasters 2006 BRM that has 430,000 kilometers and and in the process of replacing the DMF. I decided to stick with the more reliable Luk DMF since my wife will be driving it as well. We have two 2006 now and I want the engagement of the clutch to be hopefully the same between the two cars.

I just got the transmission out last night and want to replace the flywheel clutch assembly this morning. I can do the above but I am more concerned as to what causes the oil seal to wear out and if it should be replaced or not.

The concern I have is that a rubber seal wears a groove in the shaft as my cam seal has done and a teflon replacement would just get torn up if this is the case with the crank.

Maybe A5INKY can or others with experience can tell me if the crank is grooved from the old seal. If so how did you handle this. When I changed my timing belt and saw the wear mark from the old seal, I just put the rubber seal back on and set the teflon seal aside. Are the originals teflon or is that after market and OEM will be a synthetic rubber type. Any thoughts here if I should replace if not leaking and can I get the same type of material as the original seal if there is a wear mark.

chittychittybangbang · Nov 14, 2013

James & Son said:
Maybe A5INKY can or others with experience can tell me if the crank is grooved from the old seal. If so how did you handle this. When I changed my timing belt and saw the wear mark from the old seal, I just put the rubber seal back on and set the teflon seal aside. Are the originals teflon or is that after market and OEM will be a synthetic rubber type. Any thoughts here if I should replace if not leaking and can I get the same type of material as the original seal if there is a wear mark.

Factory seals were all Teflon. If rubber, it's a German replacement. A replacement OEM Teflon one should bridge over a small groove. FYI, I have the special seal tool and can rent it, send an email if you need it.

A5INKY · Nov 14, 2013

James, if it is not leaking, I wouldn't touch it. The seal does not contact the crank directly at all. Instead, the crank's sealing surface is the pressed-on tone ring. It has been years since I changed mine and have come across no others in need of attention since. I don't recall the seal material but have come to understand it to be quite robust and not a common leak source. Mine had been damaged by a sharp pointed object through the crank sensor mounting hole. No idea how that could have happened, but it was dealer serviced back then and dealer techs sometimes do the silliest things.

James & Son · Nov 14, 2013

chittychittybangbang
Veteran Member

Factory seals were all Teflon. If rubber, it's a German replacement. A replacement OEM Teflon one should bridge over a small groove. FYI, I have the special seal tool and can rent it, send an email if you need it.

http://i.imgur.com/Icf7lKF.jpg.
As usual took longer than expected. I don't think I will need the tool but glad to know you have it for rent. Thanks

A5INKY
Vendor
w/Business number

James, if it is not leaking, I wouldn't touch it. The seal does not contact the crank directly at all. Instead, the crank's sealing surface is the pressed-on tone ring. It has been years since I changed mine and have come across no others in need of attention since. I don't recall the seal material but have come to understand it to be quite robust and not a common leak source. Mine had been damaged by a sharp pointed object through the crank sensor mounting hole. No idea how that could have happened, but it was dealer serviced back then and dealer techs sometimes do the silliest thing.s

Ok, that is good news as the seal looks good. Excellent.

A5INKY · Nov 14, 2013

James & Son said:
...http://i.imgur.com/Icf7lKF.jpg...

Wow! James, that pic is a feast for the eyes

. So much going on, screw jack from the trunk, wrecking bar, tie-down strap, 2X4 block, a bread sack, and another plastic sack with a paper towel in it. You sure know how to make use of your "tools". Work in a pipe wrench and a claw hammer and I will be really impressed!

DanG144 · Nov 15, 2013

It does take a lot longer to grind out the center cover. That is not light gauge steel. We've had to do it a couple of times.

James & Son · Nov 15, 2013

DanG144 said:
It does take a lot longer to grind out the center cover. That is not light gauge steel. We've had to do it a couple of times.

A plasma cutter works fairly well. You do have to be carefull as I found out. But I was able to get all my bolts out.

MyAvocation · Nov 16, 2013

chittychittybangbang said:
Factory seals were all Teflon. If rubber, it's a German replacement. A replacement OEM Teflon one should bridge over a small groove. FYI, I have the special seal tool and can rent it, send an email if you need it.

That's in-line with what I read regarding crank seal materials. Bentley warns Teflon must be replaced with Teflon, while either can replace rubber.

In proper context this referenced the front seal on a AVH gasser. We received a rubber replacement (spring loaded) but original was Teflon. WorldImpex said they never had a complaint, but a VW guru warned to leave it alone if not leaking.

eyyopomps · Mar 4, 2015

Can you replace the rear crank seal without draining the oil? I just put full syn in like 100 miles ago haha

Stutgart · Mar 4, 2015

Can you replace the rear crank seal without draining the oil?

Yes, I can. ( Thanks to very clear and excellent instruction from A5INKY. )

Please Help! Rear Main Seal Replacement Tonight

Ol'Rattler

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mnguy

Well-known member

DanG144

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Ol'Rattler

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mnguy

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mnguy

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Saiga542

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Barnitz

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325isbimmer

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James & Son

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chittychittybangbang

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A5INKY

Vendor , w/Business number

James & Son

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A5INKY

Vendor , w/Business number

DanG144

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James & Son

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MyAvocation

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eyyopomps

Well-known member

Stutgart

Veteran Member