Exhaust valve stem seals (or not)
Turbo Mini Forums

What is the current thinking for turbo applications ???

I've done the search and from several threads the opinions seem to be about 75% against, 25% for, but most of the threads I could find are quite old.

There have also been a few threads on sticking exhaust valves - is there a corellation between this and stem seals, or is it just down to the diameter the guides were reamed out to ???

Also, is there still evidence of excessive wear on the exhaust guides when the seals are fitted (earlier posts suggest yes) ???

I'm assuming bronze guides (in whichever version) are being used.

Thoughts please.

Schrödinger's cat - so which one am I ???

i didnt bother. i get a small puff of smoke if the cars sat idling for a whjile but lets be honest, does it matter?

for example, while idling what to run it looks clean, when do the burn out it gives a tiny bit as i raise the revs, then down the strip nothing.

Guess if its to sit in traffic a lot then maybe, but for a weekend toy/track/drag car i wouldnt bother

mines really badly smokes, i have just had fitted recently some special exhaust seals from MRA minis and some avonbar inlet ones, not sure if the valve springs have ruined them and i have excessive wear in the guides but im assuming the turbo smokes as there was some unwanted substance in my last engine build which worked its way through the turbo.... but it doesnt smoke when on boost only on overrun and idleing, it gets worse as the oil gets hotter.

That is all useless info probably :( but i had been advised not to use seals on the exhausts... i suppose if you have new valves and guides you wouldnt really want to use seals? as you want to lube them to let them settle?

I never fit them on performance engines/heads.

I replace what i take off, and there is no harm in fitting 8 rather than just 4.

Johnny, I would suggest its your guides, mine did the same when you closed the throttle quickly. The engine just sucked the oil past the valve stems the second you florred it the smoke would clear and the hotter oil gets the easier it will be to siphon.

Own the day

As they don't exist for the sodium filled turbo exhaust valves, you don't have a choice if using them.

I have them on the road car and not on the racer, they're not needed really and I'd run without them happily.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Can you not buy some suitable Viton for the 8mm stems?

If something is worth doing, it's worth doing half of.

All three Metro Turbos I have owned had 8 fitted

Own the day

I think that thay are NLA now though, which is what I meant.

On 3rd Sep, 2009 Mr Joshua said:
All three Metro Turbos I have owned had 8 fitted

On 3rd Sep, 2009 wil_h said:
As they don't exist for the sodium filled turbo exhaust valves, you don't have a choice if using them.

I have them on the road car and not on the racer, they're not needed really and I'd run without them happily.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I don't have any fitted on the exhaust valves, my enigne does smoke on startup, but is pretty much ok when running.

Team Racing

I never fit them on the ex on any Turbo cylinder heads, simply because the exhaust needs all the lubrication it can get. These things get cooking hot don't forget.
My engine doesn't smoke at all, & even if i did I'd rather have a little bit of smoke than the possible damage caused by a valve siezing in the guide. Don't forget most of us are pushing these things way beyond what was expected of a production car, so just because they may have been fitted from the factory, doesn't mean we should.

WWW.TURBO-MINI.COM

Well put!

indeed, that man with a hot sister is right

Team Racing

on my K100 head it came with all 8 fitted. went to BMW to get more and looked on the their parts diagram and it showed all 8 has them. So i fitted all 8, but thats just me.

Thanks all.

Ignoring the BMW etc heads, just A series, I think the answer is mostly what I expected.

Phil's answer most explicit.

Joe (mini13), did you have stem seals on the exhaust valve that gave you problems - that question was hidden half way down my original post......

Edited by Rod S on 3rd Sep, 2009.

Schrödinger's cat - so which one am I ???