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Rear Crankshaft Seal Replacement

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randall977
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Rear Crankshaft Seal Replacement

Post by randall977 » Wed Feb 21, 2018 3:58 pm

I've looked around but I can't find a write up on replacing the rear end crankshaft seal...is there one somewhere?

If not I will do one, but there are a few things I wouldn't mind confirming before I do the job;

1. Do you need to take off the seal and aluminium surround at the same time?
2. Does the oil need to be drained out of the engine?
3. I notice that some seals have a plastic piece with them - is this to aid application?
4. Is there any particular brand / part number I should get?

Many thanks!
Last edited by randall977 on Wed Feb 21, 2018 10:13 pm, edited 1 time in total.

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Re: Rear Crankshaft Seal Replacement

Post by hornhospital » Wed Feb 21, 2018 8:30 pm

1. Yes
2. No, but it'd be a good time to change it.
3. Yes, but more to maintain the shape while in storage.
4. Cross-reference it using Realoem.com, then search the latest part number on Google. You'll get many vendors that carry it. As to brand, I'd stick with one of the European-made ones, but avoid the URO brand. In spite of the name, they're cheap imports from the other side of the world.
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Re: Rear Crankshaft Seal Replacement

Post by randall977 » Wed Feb 21, 2018 10:15 pm

Thank you for the reply - very useful! I will do photo record of the job when I do it - which will be soon.

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Re: Rear Crankshaft Seal Replacement

Post by wattsmonkey » Fri Feb 23, 2018 11:25 am

The Bentley manual for the E28 is brilliant. American, so includes lots of emissions stuff, but the M30 engine write ups are absolutely crystal clear.
"Most of it necessary; all of it enjoyable[!]" LJKS
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Re: Rear Crankshaft Seal Replacement

Post by Steve Corbett » Fri Feb 23, 2018 11:00 pm

Use caution not to damage the end of the oil pan seal. I currently am doing a rear seal on an E28 535I and the previous mechanic cut the oil pan seal off when he removed the rear main seal and used RTV to unsuccessfully reseal the pan. Now I will need to support engine to replace the pan gasket next.
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Re: Rear Crankshaft Seal Replacement

Post by Ralph in Socal » Sun Feb 25, 2018 7:22 am

The rear seal job creates “Mission Creep” as far as you are willing to go

As Steve C. points out, the rear seal carrier overlaps the oil pan gasket. The oil pan gasket also overlaps the front cover gasket so care must be taken when changing the oil pan gasket. Realistically, the front crank seal should also be replaced. The front cover with the front crank seal should not be removed unless you are also changing the Head Gasket.

I would inspect first to determine if you actually want to remove the rear seal carrier. A dedicated seal puller should be able to remove the old seal without removing the seal carrier.

As with most old seals that have been installed for many years, you may experience difficulty pulling the old seal out. It helps to break the “bond” between parts that have been together for a long time. You may have to drive the seal further in to break that bond and allow for ease of removal

I always coat the outer edge of the seal with additional sealant to ensure no leaks. Overkill but I would rather than have to go back and do it again. A little oil on the seal lip that contacts the crank and you’re good

Ralph
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Re: Rear Crankshaft Seal Replacement

Post by randall977 » Sun Feb 25, 2018 8:06 pm

Very important info there - thank you! I like the phrase 'mission creep' - brilliant - there's certainly been some of that gong on. My original plan was to get the car going drive it around looking presentable. I've now removed nearly every item so I think I may as well do a full resto - just painted the rear diff...which I had to remove to get the rear suspension off to be able to weld the ends of the sills...

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Re: Rear Crankshaft Seal Replacement

Post by baders » Tue Feb 27, 2018 1:19 am

I did all of that, and then did an engine swap :shock:

It's madness I tell you.
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Re: Rear Crankshaft Seal Replacement

Post by hornhospital » Tue Feb 27, 2018 2:23 am

An old quote that pretty accurately sums up mission creep in the middle stages:

It's difficult to recall, when you're up to your ass in alligators, that your original intent was to drain the swamp.

:roll:
Ken Kanne
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Re: Rear Crankshaft Seal Replacement

Post by TN_M6 » Fri Mar 02, 2018 10:50 pm

Children's book... "If You Give a Mouse a Cookie"... should be required reading.

Don't forget to also polish the journal and if their is any sort of groove consider setting the new seal a little deeper. You want it to be even though not crooked or it accelerates wear.

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Re: Rear Crankshaft Seal Replacement

Post by randall977 » Sat Mar 03, 2018 10:26 pm

Replaced the seal today with current part number seal 11142249533 - as found on ETK. I used a Corteco PTFE type ring seal, the one I removed was different in that it was a radial spring type seal. The original looks more substantial and I'm now a bit concerned that I have downgraded a seal which wasn't leaking for one which is more likely to. I pushed it all the way in until it stopped at the metal step btw.

Seal.jpg
Seal.jpg (344.08 KiB) Viewed 1274 times

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randall977
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Re: Rear Crankshaft Seal Replacement

Post by randall977 » Sun Mar 04, 2018 9:42 am

In case you're interested, here is the lowdown on ptfe seals...

https://www.linkedin.com/pulse/why-use- ... -rotary-ed

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