valve stem seals?

[raygreenwood]

I have heard bits and pieces of conversation in both directions. I have never built a type 4 with stem seals before. I think Jake made comment about them several years back. What do you guys thinks....seals or no seals? Pro's and con's? Ray

[blue77bay]

Hi Ray,i have built a few over the years and never used seals,never had an oil consumption problem either,my reasoning,valves are horizontal or angled down at the tip slightly so at sane rpm's oil is below the valve stem and doesn't pool above the guide to be sucked down, of course it depends on the correct stem to guide clearance as well. I have seen a few built with an o ring over the stem but ( in my opinion ) i cant see that being effective at all as it will simply sit on the stem at max lift and do little,most i disassemble that have had hats fitted have become very brittle and fallen off, but in each of these instances the guides are still worn out, however i can only assume they started from a correct clearance and valve geometry was correct

[fusername]

vanagons use a square shouldered oring on the intake valves, to seal at full lift when presumably there is the most pull. you could get a handfull of those if you wanted. someone had a loooong rant on the topic, along with modification and installation guides for a T1. one of the big popular guys, but I can't think of who right now.

[Piledriver]

The viton "umbrella" type seals should be the "most likely to work/least effort" no machining required combo.

In one previous discussion, HAM made the excellent point they are really only beneficial to keep oil out of the intake, so intake only.

NAPA has them IIRC listed for the Vanagons.

[type411]

Volkswagen Werk stopped using them at some point or year to get more oil to the guide and stems.
I have never used them in 30 years. The boxer engine dont use oil that way like en upright engine does.

By the way Ray, I followed your advises regarding crank case ventilation, and it works fine on my latest engine. Just cant believe that we have been doing that wrong for so many years

[Piledriver]

I have never used them either, they were discussed in reference to hipo/boosted builds where it is critical to prevent oil entering the intake.

If the clearances were right, the umbrellas should be OK as they only form a labyrinth seal, some fine oil mist will still get where it needs to go. (intakes only)