I didn't notice anything while driving (smoothly on the highway, no hills, no traffic). After getting home and out of the truck I noticed a strong smell of burned oil. Looked under the front and there was raining oil from the front axle. The left (drivers) side of the engine compartment was all covered in oil. It came from the front seal and the HB pulley had sprayed it around. After removing the pulley I saw the reason:



It was blown out for whatever reason and almost fell off after removing the pulley. So I got a new seal (ERR6490G, LR genuine, $27) cleaned everything, put it in and guess what? It is still leaking, although not as badly as before, but it is still leaking oil at the front crankshaft.

What could be the cause of a blown out seal?
1) crankcase pressure (but my PCV system is not clogged, I did the PCV valve mod recently, everything is clean)
2) crankshaft play
3) worn HB pulley shaft

I noticed a very fine groove on the shaft, but I couldn't feel it with my fingernail. I smoothed it with 2000 grit sand paper just to make it nice and shiny. When sliding the HB pulley back in, I felt no resistance at all. I think there should be at least some from a fresh seal. Maybe this is a sign that the shaft is worn out and the seal does not not make contact with the shaft sufficiently?

So I ordered a new HB pulley ($529) and let's see what happens.

BTW: Removal was very easy. I used a compact impact wrench (Husky H4435) which fits between the radiator and the pulley. The pulley came off almost by itself, so I didn't even need to use a puller. Obviously it was not sitting tight. Maybe that led to wear on the shaft? The seal itself looked good, the lips are all intact. It was an aftermarket part (Victor Reinz), so a previous owner hat it replaced already.

EDIT: I just checked the measurements stamped on the removed seal "49 63.5 8/95". 49 seems to be the inner diameter in mm. In contrast, on the LR genuine part, which I put in, it reads "50 63.5". It is 1 mm wider than the removed one, which would explain very well why it still leaks. To me it looks like a previous owner had already trouble with a worn down shaft but fixed it by using a narrower seal.

 

Interesting...

 

SKF makes something called a Speedi Sleeve, which is a thin walled sleeve that slides over a worn shaft so the seal won't leak. www.skf.com

 

That would save me a ton of money. After reading the whole Interwebz over the weekend, I heard about that too but no one had a size / part number for a Discovery-II. It looks like it is more a theoretical solution, or do you have a size/part number which works?

Another option is to machine the HB pulley shaft and get a smaller sized seal. The problem is that I couldn't find a seal just by looking for diameter.

 

99192 speedy sleeve. National (Federal Mogul) or C/R or SKF.

 

Thanks a lot. Did you try that with success?

 

I have done the speed sleeve, works great. They actually work better than the oem pulley because they are chrome plated hardened steel. Make sure to get the right seal. Also, to check the PCV is working, you can stretch a balloon or latex glove over the oil fill tube with the cap off - there should be slight suction. Any inflation or no suction is a problem with the PCV.

 

I used one on the output shaft on my Dana 300 on my Jeep. Does work great, still on.

 

After installing a new HB pulley it looks like the leak got fixed. The HB pulley was expensive, but it was the only thing I could do, since the rubber on the old one was cracked. Fixing the shaft with a sleeve was not an option. The leak was indeed caused by a groove on the shaft exactly at the position where one lip of the seal sits.

I drove 60 miles and I cannot find any traces of oil around the front seal anymore. I also have the impression that engine vibrations got reduced a little bit.

There was also the opportunity to clean the camshaft sensor and the area around it, and, more importantly to replace the sensor's o-ring. Possible, that there was a small oil leak as well. The old one went into pieces like brittle plastic when trying to remove it. I got a new one for $0.99 from O'Reilly (National Part #115, ID 11/16", OD 7/8").


Cracked rubber on the HB pulley.


Groove on the HB pulley shaft.


Locking the crankshaft with a crow bar while tighten the HB pulley bolt.

 

Good write up.

I always hit up NAPA when I need to find just the right part. Seals, bearings, etc. Sometimes they can check various parts and find one that meets what you need. Glad it worked.