Crankshaft oil seal

DavidThompson · Posted: Sat Jan 13, 2024 4:02 pm Post subject: Crankshaft oil seal

A previous owner has fitted an oil seal in the crankcase end plate which has now failed. Engine is a 4.5litre
The crankshaft "nut" against which the oil seal acts is 39.7mm dia. Would an oil seal with id of 38.1mm (1.5") work satisfactorily ? or do I need one nearer to the dia of the "nut"?

All help gratefully received. I cannot identify the id of the failed seal with any certainty as it has become very hard and cracked.

Iain Warner · Posted: Wed Jan 17, 2024 4:30 pm Post subject:

David
I had an oil seal retro fitted into the ring plate that hold the crankshaft thrust bearing at the front of my 3 litre many years ago. A couple of years ago I noticed an oil leak, and on disassembly I found the seal had worn a groove where it runs on the body of the 'nut'. I cannot recall the size of the new seal but I do know I 'repaired' the nut surface by using an SKF speedi sleeve. Suggest you examine the surface of your nut before reassembly.
Iain

DavidThompson · Posted: Thu Jan 18, 2024 4:54 pm Post subject:

Iain
Your reply is very useful. I am told the seal id should be 1 to 2 thou smaller than the shaft dia, and had identified an SKF seal 39.66mm id that would serve to do the job. The od is smaller than the failed seal, and so I had thought to buy a new end plate (or get one made) to hold the new seal.
Now having examined the "nut" more closely I see there is a wear mark - although I wouldn't go so far as to call it a groove - and measuring across the mark the dia is 39.66 as opposed to 39.7 mm. This of course is exactly the same dia as the SKF seal identified as a replacement, 1.57 thou less than the surrounding shaft.
it seems I now have to turn down the shaft to the next popular id seal or fit an SKF Speedy Sleeve