It sounds like they are Todd Miller's Viton seals. Often they are slightly loose, I always apply a little Loctite inside them before fitting. Don't hit them on too hard, be gentle...
These seals are great, they don't go hard like both the Mini 1275 and Metro (with spring) ones do.

BTW, all Mini heads including the 998 had 8x 1275 type seals fitted from about 1976 onwards.

Kevin G

The seals were on the head/engine when I got it.  They are metal jacketed from what I can tell.

The head does have little grooves in what I believe is the guide.  I think these grooves are for the bottom of the seal to hold.

I'm wondering if I have to remove the caps/springs to press them back into place.

I have yet to run this engine so I don't know if it will run or if it will smoke if it does run.

Henry

Normally, 998s run the simple o-ring valve stem seal that goes up and down with the valve's movement.  Your photo shows a "top-hat" seal normally associated with 1275s only.  The valve guides of the 998 do not have the groove in them that allows the top-hat seal to attach to the guide, so they will lift off the guide as soon as it is used.  The top hat seals need to be used with the grooved guide.

The photo makes it look like the seals you are using are metal-jacketed, that makes me think they are metric/import application that has been used.  However, this may be a misinterpretation of the photo.

Were the seals included in the head set, and where did you buy it?

MMM 

 

It looks like the valve stem seals may be too tight on the valve stems. The seals are to keep too much oil from being sucked down the valve guide but they should allow a small amount through to lubricate the guide. If they seal too well the valve guide and stem will seize.

Rubber valve stem seals are usually compliant enough that they allow a little oil through. I'm told teflon seals have to be sized to allow a little oil through to lubricate the guide.

It is possible that the valve stem seals are ok and that they just aren't being held on to the guides well enough. However, since one possible consequence of having a valve seize is a complete engine rebuild you should either make abolutely sure that these are the right valve stem seals, installed properly or just leave them the way they are and live with the extra oil.

Cheers,

Kelley

"If you can afford the car, you can afford the manual..."

Just looking under the rocker cover of the 998 and I noticed that the intake valve seals don't look right.

Should they be attached to the head at the little groove that is cast into the head?

I tried to press it down but it would not stay after I turned the engine over.

Henry