Valve stem oil seals

I’m going to take one of my Spada heads off shortly ready to get it “done” and hopefully cure the plug oiling up - I think it needs the valve guides doing.

Does anyone reckon it’s a good/bad idea to get the new guides machined to take seals, or maybe just the inlet?

Ian

know i person that fitted seals to a bike that they were never fitted to guides lasred 5,000 miles before worn due to np lube on them
and why only inlet ?

Inlets usually the ones to suck oil down em when worn.

Seals need lube on the stems to survive.

Well fitting valves and guides will be ok

Hi, fitting new valves and guides will do the job, however from what you were saying about your plugs oiling i would check your piston rings and cylinder bore ware if i were you , from my experience when my guides were worn out so were the piston rings. All the best, chris.

Or head gasket blowing between bore and pushrod tube

…or just give it to NBS! Come and listen to my T3 post top-end rebuild…loverrrrly!

^ What they said that’s a helluva lot of oil just going down a valve guide, I’m not convinced either. Presumably if guides needed seals Guzzi would have put them in at the factory. (?)

Another possibility is it’s coming up one of the four cylinder studs that have O-ring seals at the top, not the bottom, and thence through the head gasket.

Or, O-rings are missing from the short studs, the only two to have them at the bottom. Or, someone has put the old ones back on or never replaced them with new, which you must do every time cylinder is dismantled.

General wisdom seems to be not to add seals to guides - says same in Guzziology too. I’m going to delve about a bit more, but suggestion is that I need to convert to a Le Mans breather which cuts off one source of oil to the induction side. It’s SORN’d at the moment so will have to wait until next year to see if cures it.
I don’t think the heads have been off before so shouldn’t be any O-rings missing.

Some years back I thought it might be a good idea to fit guides with seals to my 650 Triumph. So I did! The guides wore out in about half the mileage I’d been used to without seals.Never did that again. :open_mouth:

Lots of engines “recycle” oil breather “mist” into intake but don’t emit visible smoke in exhaust or oil up plugs, so there must be some other reason.


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People who’ve ridden behind me say it doesn’t smoke visibly. It only has a problem on one side so I’m not convinced it’s the breather but won’t know till I get it back on the road again. I’ll have a look down the intake port when I get chance and also see if I can wiggle the valve at all.

I doubt it due to the strength of the springs, only one absolute way to be certain - take it all to bits and check / measure everything - Murphy’s Law says you may find that it’s something else that is completely different and unexpected.