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Re: Plume of Smoke (was: [T3] Various Questions)

On 13 Nov 2003 at 21:43, joshua brooks wrote:

>    I recently took apart a type 3 engine with valve stem seals on the heads. 
> It was a high milage engine and the valves were shot but the seals were 
> still supple and seemed to be in good condition. I asked my local vw parts 
> house about valve stem seals and they said they hadn't been offered in years 
> because they weren't needed with modern valve guides.

I believe that all air cooled VW engines came with these square cross section O-
rings right up to the end of production in 79. The reason you never saw them, 
however, is that they usually become hard and break off before the engine 
reaches rebuild time. They end up as little bits of hard black stuff on the oil 
sump plate when you change the oil.

Most shops don't know about them and certainly don't replace them. There's no 
room for them if you use big cams or high lift rockers, so the performance 
folks never mention them. There's some thought that some oil on the valve 
shafts ought to be a good idea, but no other cars use that philosophy, so I 
think that can be ignored.

Equally ignorable is the claim that valve guide metallurgy has advanced so you 
don't need them. I think the real problem with letting oil down there is that 
it's REALLY hot down there and the oil chars and stiffens and can make the 
valve sticky in the guide.

I haven't done lots of testing with and without them. I just bought a handfull 
years ago and install them on every engine. The puzzle to me is why aren't they 
included in the gasket sets since I thougt every VW used 8 of them....

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

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