Valve stem oil seals

VicS said:
How would you explain this one? ( no prizes for identifying the car though) Click, click and click again to get the image fullsize

Part #5 is the oil seal

View attachment 72343
Click to expand...

That looks like it could be one of these oil-deflector things which go up and down with the valve stem as described above. However, I would need to see it assembled with the valve guide to be sure.

Richard
 
pcatterall said:
Note that there is no groove on the exhaust valve stem though possibly a cap would just locate itself, sitting at the top of the guide when that valve is closed?

I guess that some oil 'mist' getting to the valve stem is desirable?


Over to the experts again!!
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I'm no expert, but yes, the guide does need oil and I'd bet that getting the quantity right is almost an entirely empirical/experience-based part of the design process. I'd imagine it's not just for lubrication either, the oil will help with cooling too.

Having looked at your picture I can see why you're a bit dubious and the evidence seems to suggest that an experience-based decision has been made and it was judged that the O ring was allowing too much oil, or the umbrella not enough. Snag is that you don't know which. If I was on a Golden Globe boat with no comms I'd go for the O ring to be safe - thankfully you're not and in your position I'd 'phone one of the better re-builders and ask to speak to a friendly person there.
 
pcatterall said:
Ang on ang on !! You have got me thinking again ( never a good thing!)
The cup seals supplied View attachment 72344 are not a tight fit onto the valve guide nor is there a locating groove on the guide.
my photo shows a closed inlet valve with the cup fitted into the groove on the stem where there had previously been an O ring.
I assume that the O ring would have just sat on the top of the guide to prevent oil running down the stem, I GUESS that using the cap instead
means that the 'umbrella effect' quoted previously prevents oil entering ( to an extent) should the valve stop open?

Note that there is no groove on the exhaust valve stem though possibly a cap would just locate itself, sitting at the top of the guide when that valve is closed?

I guess that some oil 'mist' getting to the valve stem is desirable?

I can go back to parts4 engines but cannot expect them to have an answer to questions of such detail on all their stock.

Over to the experts again!!
Click to expand...

Indeed .... you do need some oil getting down between the valve stem and the guide which is why the usual type of fixed seals do not scrape the stem 100% clear of oil, especially on the exhaust valve which is subject to much higher temperatures. I think your seals are these umbrella/deflector types that do not locate securely on the top of the guide but will move up and down with the valve.

Richard
 
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