Cylinder Head (2.1 DJ) - Valve Stem Seals?

[Yozza]

Ay up,
When I stripped the cyl. heads I noticed a black circular seal sat around the inlet valves (square x-section), I assume these are to stop oil finding it's way into the heads? I also assume they must need replacing as they were very hard, or is that standard?
Should there be seals on exhausts valves as well? When I had a look in my 'bentley' manual, the exploded view did NOT show the seals? (later addition??)
Lots more questions - sorry, but it's an interesting learning curve.
Cheerz

[Red Westie]

Interesting.....although I worked at a main VAG main dealership for over 6 years I never stripped a WBX. What I can say is all VW engines have valve stem seals and they were prone to going hard over time and this is/was exagerated by certain driving conditions (constant high speeds etc with high temps).
Coming into 'this scene' twenty years on...I was led to believe that the WBX wasserboxer was the VW 'exception to the rule' and that valve stem seals are/were not fitted! you have just kicked that myth into touch.
All other VW engines (circa 1980 - 1995 at least) have a seal on BOTH inlet and exhaust valves. I can see why you would only fit them on the inlet, as this is the valve that is open at the same time as being subject to 'vacuum' (INDUCTION STROKE) the exhaust valve is closed at this time so the valve guide and seal are not being exposed to this 'sucking' negative vacuum which is what primarily draws oil down the valve stem.

Replacing valve stem seals on 4, 5 cylinder inline VW engines of that era was very common.

Symptoms caused by worn/hard and broken seals are fairly pronounced, typically: a puff of oil smoke AFTER a period of engine overun. So fairly high revs, hot engine, driven on a by-pass or similar where the engine is kept in gear on overun (vehicle being slowed by the engine) with fairly high revs for 5 - 15 seconds . What you are looking for is a big puff of smoke the moment the accelerator is re-applied.

Martin

[bigherb]

VW stopped fitting valve stem seals to flat four engines in the mid seventies. Gasket sets still came with them though. Possibly your engine has been repaired before and someone fitted the seals.

[Yozza]

Brilliant replies fellas, learnt alot there - thanks!
I've just ordered a new engine gasket set, if I see the seals in there should I just leave them alone then?

[Red Westie]

Well if they can be fitted to the inlet guides then I would fit them....
Martin