Crankshaft oil seal advice

[411514]

I'm hoping for some advice on the best crankshaft oil seal to use, and also the best way to fit it.

By way of background, I was changing the timing belt on my 2.0 HDI 8v 110 recently, and thought that whilst I was there I would change the crankshaft oil seal as a preventative measure. It wasn't leaking, but I guessed that after 200k miles it must be on its way out. Big mistake as it turns out.

I replaced the seal with a genuine Cit part, but when I was next doing an oil change, approx. five weeks later, I noticed that the seal was now leaking engine oil. Not a huge amount, but enough to make a mess and annoy me.

So I replaced the seal again, again with a genuine Cit part, but I have just changed the oil again and the second replacement is leaking oil just the same as the first. Again, not a massive amount, but is making a mess.

The only reason I can think for both replacements leaking is because, as I noticed when I changed it last, the original seal seems to have worn the crankshaft slightly (not unreasonable I guess in 200k miles). The worn area is not noticeably indented, but just appears as a polished ring about the crank. I can only assume then that I am not getting the replacement seals lined up with this ring perfectly, and thus oil is leaking past.

It seems pretty much impossible to me to get the replacement seal lined up perfectly. Thus, I have a third genuine Cit replacement, and my plan was to fit this one a good 1 millimeter or so offset from the 'correct' position, so that the new seal engages a 'fresh' part of the crankshaft. First question, is this an OK idea?

However, I am now having second thoughts. I have just noticed that SKF sell 'double lip' seals. Thus, I think that I will instead fit one of these double lip seals instead of the genuine Cit part. Indeed, the original Cit seal is 7mm wide, but I am considering getting an 8mm wide double lip seal, just so that hopefully the seal engages the crank in a different spot.

My main question is, does anyone (any chemists here?) know the difference between Nitrile rubber and Viton rubber, and know which is best suited to use as a crank seal. My understanding is that the original Cit part is nitrile rubber, and it seems that 'Viton' is a Du Pont trade mark for some proprietary rubber compound. I thus have two options for the double lip seal, either nitrile or Viton, as below:

http://simplybearings.co.uk/shop/p30726 ... _info.html

http://simplybearings.co.uk/shop/p30929 ... _info.html

I am leaning towards using the first seal, i.e. the nitrile rubber seal simply as it appears this is what Citroen used, but I wonder if anyone has any input in this respect. Is Viton suitable/better?

Thanks. Apologies for length post.

[lexi]

The double lip seal is a good idea. Viton is superior to Nitrile in durability. It is tolerable to many other oils, including Veg.
If you can get a double seal the same ID and it fits in depth, then it should run on an unused part of shaft. You need to lube the seal with oil on fitting, so that it does not start up dry. I think that will work.
If not, you can reface the shaft with an SKF Speedi sleeve. It is a very thin tube that goes over the shaft and lets you use the same dia seal. They are around £20. Bit of a faff with pulleys being put on and off, so ATB with your repair. Funnily enough, I was going to renew mine last year while in there. I left it as no leak and 110k. Maybe it has a few miles left.

[411514]

Thanks Lexi. Food for thought. I will consider the SKF sleeve. I would certainly advise that, if your oil seal is not broken, don't fix it. I wish I had never touched mine. For reference, I changed mine on 203k miles, and it was still sealing perfectly, not a drop of leakage.

[HDI]

Almost certainly due to a new seal running on a worn shaft. If it ain't broke..............!

[411514]

If it ain't broke..............!

Certainly, I wish I hadn't touched it. I wouldn't necessary say the shaft is worn though, and so I'm not yet entirely convinced that this is the problem. Like I said, there is a polished ring about the shaft from the old seal, but it isn't perceptively indented, just polished. I haven't yet had the chance to replace the seal again, but I plan to do so soon, and will install it slightly offset to avoid the polished ring, and will report back.

In the end I purchased the 8mm wide SKF 'double lip' nitrile seal. FYI, it seems that 'double lip' is slightly misleading. The 'double lip' seal in fact only has one oil sealing lip (spring biased), the second 'lip' is more of a dustguard to the first lip. It doesn't seem that the second lip forms an oil seal. In this respect, the genuine Cit seal is 'double lip'.

[lexi]

The double lip is sometimes just a double groove on the one seal ring. Nothing wrong with Nitrile for that application. Although Viton is superior and more expensive as a base material, it is not to say that any old Viton seal of no real make, will be better than a Corteco or Gen parts Nitrile. Are you still losing oil?

[411514]

Lexi, yes I am still losing oil but I am still on the old seal, I haven't swapped it yet, I probably won't get the time to swap it for a fortnight.

You mention Corteco as being a good brand, is this correct? My assumption has always been that Corteco was a budget brand, and so I have always avoided their parts, but I will be interested to hear if I am wrong, particularly as ECP often have Corteco parts cheap.

[lexi]

The SKF seal you bought should be a goodie. IME Corteco is good. Citroen seals are sometimes Corteco, as are other car makers.

[411514]

Just a brief update.

I got round to doing this job at the weekend. Stripped off timing belt covers and belt et cetera planning to swap the crankshaft seal and had a good look around. Noticed a fair amount of oil flung around the timing belt area, but on closer inspection, noticed that the oil was in fact coming from the camshaft seal, rather than the crankshaft seal. I took of camshaft pulley, which indeed confirmed this. Quick dash to EuroCarParts produced a Corteco seal (I know that some don't approve of ECP but I think they are excellent, our local branch always has stock of the most obscure parts). Camshaft seal duly replaced and a few hundred miles later all is well.

Guess this demonstrates that one should always investigate the issue thoroughly rather than swapping parts. It turns out there was nothing wrong with the crankshaft seal all along. The only reason I immediately suspected the crankshaft seal and so did not check properly, indeed ignored the fact that the crankshaft seal was not noticeably leaking, was simply as I had just replaced the crank seal, and though it too much of a coincidence for any other seal to be at fault when there had been no oil leak prior to changing the crank seal. Turns out I was wrong, must have been a coincidence. Indeed, I guess this vindicates my pre-emptive changing of the crank seal in the first place, inasmuch that if the camshaft seal has failed, the original crankshaft seal surely wasn't far behind.

For reference the camshaft seal failed at around 210k miles.