1 8t Front Crank Seal Replacement

Busy day today, as I decided to try to replace the front crank seal that was my last oil leak of note.

Others might want to do this job, but may be a bit scared of the unknown. This is how I did it…..

We'll start by assuming we've got he front end forwards and all the aux belts and fan off etc. leave the cam belt on at this stage.

First things first, we need to get the bolt off that secures the cam belt sprocket. This is on VERY VERY tight. The only way you will remove this bolt is by locking the crank still and using a long lever.

I decided to make a tool out of some aluminum stock I had. I marked out the position of the holes using the drive belt pulley as a template. I then drilled them to suite and also machined a large hole in the middle to allow the 19mm multi-hex socket through and for it to sit squarely on the sprocket.

And yes, one of the holes is meant to be off center.

It then bolts up snug to the sprocket…

And allows the socket through…

Note how I left the cam belt on until I'd undone the bolt. One slip without the belt and you could damage something and lose your reference points.

The ally bar then rests on the alternator pulley, or the A/C mount bracket, depending on whether you are loosening or tightening the bolt….

Was it Arcamedes who said "Give me a lever long enough and I'll destroy anything?

Seriously, this is what it took to undo the bolt….. Unless you can get at least a 4 foot long bar on your socket, you are in for a long afternoon. I'm 6' 4" tall and it took some heaving.

Once the bolt is cracked loose, remove the cam belt making sure you make a note of all the relevant positions.

Here is the bolt out, the pulley off and the new seal awaiting fitment.

And a pic of the old leaking seal…

To remove the old seal, carefully drill two small opposing holes in the front face of the seal, being certain not to damage either the crank surface or the housing the seal sits in, because if you do, you're in a world of pain. Insert by about 5mm a couple of self tapping screws into the seal and pull the seal out with some long nosed pliers.

This was a real pain, as the first screws just pulled out so I had to use bigger ones. With a lot of swearing and messing, the seal popped out, but beware, it is in there quite tight and needs some real pulling.

The orange you can see within the hole is the surface of the crank bearing journals.

Now you need to insert the new seal. Make sure the aperture is perfectly clean and free of debris. Then smear lots of engine oil on all the surfaces, including the seal.

The crank has a stepped surface on it and a key way slot to locate the sprocket. Getting the seal over the first step is easy, but getting it over the second step runs the risk of peeling the inner lip backwards and the spring popping out. This happened to me whilst replacing the cam seal.

VW use a special tool that is conically shaped that fits over the end of the crank and upto the second step, allowing you to glide the seal into position without having to get the inner lip to jump a step.

I didn't have this tool, so improvised (again) by cutting a section out of a plastic soda bottle and making a slightly tapered tube that just fits over the end of the crank. I smeared it all in oil and slid the seal down the tube and on to the crank. Once the seal is on the crank's second step, the outer sealing surface will be ready to insert into the housing. I removed the home made plastic tube and checked that the inner lip seal was still seated correctly.

NOTE - Using the soda bottle tube technique will also protect the inner lip of the seal from being damaged by the sharp machined edge to the key way in the crank that locates the sprocket.

This is now the tricky part - getting the seal fully seated in the housing square. Haynes says to drive it home with a large socket. Well, as I don't work on an oil rig, or assemble submarine main bulkheads for a living, I didn't possess an absolutely huge socket, and I guess most home mechanics won't either. So, I used the old seal as a drift with a block of wood behind it and knocked it in as far as I could before the end of the crank fouled the wooden block. This left me needing to get the seal in another 7mm or so. I thought about it and decided to sacrifice a role of electricians insulation tape which has the perfect inner diameter to slide over the crank. I unraveled the tape until about 5mm was left which left me with the perfect sized outer diameter to fit within the housing. The width of the roll of tape is sufficient to drive the seal in enough without the crank protruding beyond the center.

BE CAREFULL not to drive it in too far. There isn't a rear end stop to the housing and if you keep on pushing the seal in, it will keep going until it touches the crank bearing journals! I measured the depth of the original one to be about 2mm sunken below the outer face of the housing. To make sure I DIDN'T put my new seal exactly where the original one was, I inserted it another 2-3mm deeper to make sure that the inner lip has a fresh section of crankshaft to wear against rather than it sitting in the same place as the old one.

At this point, I cleaned everything off, and put it all back together again. I've had the all the belts etc on and off so many times recently, I had it all up and running within an hour, albiet with the LC still forwards.

So a few golden nuggets….

1) It isn't as hard as you imagine. I did it (my first time in about 3 hours)
2) You WILL need a long pole at least 4 feet long and some fresh underpants
3) Be careful drilling the old seal and using the screws to pull it out. Do not mark the housing or crank.
4) Make a plastic soda bottle application tool - this was a real head saver!
5) Use plenty of oil and keep everything spotlessly clean
6) Make sure you have a roll of tape or similar to drive the seal home square. Or a huge socket!
7) Don't insert the seal too far, but make sure it is a little deeper than the first, maybe 2mm, not much more to give new surface to seal against.
8) Re-torque to 90Nm + 90 degrees (according to Haynes) This seams much looser than the removal!

I hope this will be of use to someone. I'm glad I did it and to be honest, it wasn't a job I'd be scared of doing again. There are far worse!

Good luck!

Oh, and by the way - it doesn't leak now!

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