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Can anyone advise on the best type of crankshaft oil seal.
There seem to be a couple of lip configurations and materials so not sure which type to go for.
Thanks in advance for any pointers.

I buy my seals from Mdina. Unfortunately, You have to buy a kit of most of the seals.

You can buy single seals from lots of places but as you say there are various materials.

I think it is 30x40x7, but not sure of best to buy. Prices range from about £3 to £15...

I'm sure somebody will be along shortly to advise.

https://simplybearings.co.uk/shop/Seals ... index.html

Hi,

Mdina supply engine kits from Ariete and these were used by NLM for engine rebuilds.

The question is why you would need just a crankshaft oil seal?
If this is weeping the most likely cause is a worn main bearing (plain type its common)
unless the motor has stood for decades or something went wrong in the assembly.

Mark

The wear in the plainbearing is unlikely to induce a leak in the seal. It could be the allen screws are loose or one missing or not got the washer under the head. The shaft seals are usually made of nitrile or neopreen and and either are suitable for this application. The seal could have simply not had enough lubrication but unlikely and worn or just simply worn out. When fitting a new one it is best to use an engine assembly lubricant which is basically a thick oil with additives, but unless you are doing an engine rebuild is expensive, so just stick to a rubber grease and gob all over the seal, it will simply be absorbed by the oil in the engine. If you pay more than a couple of quid then you are being ripped off but do make sure it is not Chinese.
I am curently rebuilding a bottom end for someone and a set of gaco cup seals to suit the Morini either 350 or 500 is around the £10-£12 and all English made, the price difference being the manufacturer. Not wishing to be labeled an influencer, but as a sharer, a firm I now buy the bearings for Morini engines and seals is UK Bearings in Brierley Hill who supply the 500 crankshaft and gearbox obsolete bearings as recomemnded by SKF circa 2005 for the same price as the bearing before modificdation or there abouts perhaps a small premium, but over a £100 less from the quotes I had from other suppliers, Tip from long ago, if the list price for a bearing is £10 the trade price is £3.5 and that is what you should be paying, so ask for the trade price, even cheaper than Simply Bearings.

Many thanks for the info.
I’ve seen seen twin lip as well as single lip seals on offer made in various materials for different applications so wasn’t sure of the best option.

After a few miles of riding there is oil on the right hand side of the engine (visible on the ribbed area of the sump around the gear change shaft).

I have rigged-up a support for the clutch release lever so I can ride the bike without the r/h engine cover in an effort to identify where the oil is coming from.

After a run there is a drip of oil on the wire from the alternator stator, hence the plan to change the oil seal. I will also change the gear shaft and clutch push-rod seals for good measure. Other than that nothing obvious shows up.

I re-built the engine about 4 years ago and can confirm all copper washers were renewed but I will re-check the 3 Allen screws are tight. I may well have “nicked” or twisted the lip of the seal on re-assembly.

Check the camshaft seal, might as well change that one whilst doing the others... in which case, buy a kit