I’m trying to locate a small oil weep from the cam carrier area of a 748 and can see that there is a cam pulley, on the inside of that is an oil seal, on the inside of that is a spacer and inside of that is the cam. So what stops oil passing between camshaft and spacer? Cheers Ian
Magic The spacer is clamped tight by the pulley, up against the shoulder on the camshaft. It's purely a mechanically created seal. There's little or no pressure in that area. I've not seen one leak from there, the seal is the usually failure in that assembly. The o-ring on the cam bearing carrier is the weakest seal in that area, and also the the gasket behind the centre plate can give trouble, especially if it's been reused rather than replaced. As an aside on that gasket, make sure it's been fitted clean. They get replaced with added sealant rather than a new one going in. The sealant can block the oil ways and starves the oil feed to the cams etc. this is another route to rocker failure.....
When I had the ST4s it developed a tiny weep behind the horiz exhaust cam pulley. I traced it to the sleeve between the seal and the camshaft that you're referring to. I took it apart, cleaned everything and put it back together with a smear of Hylomar on the face of the sleeve that buts against the shoulder on the cam. It never leaked again
Magic you got the part number for the wand to fix it? Thanks for explaining that Nelly, it really is as simple as it looks. It’s been weeping from the vertical exhaust cam pulley area and running backwards onto the belt cover, also inside onto the belt and head area. The seal has been replaced twice and the carrier has a new o ring every time it’s apart. The centre plate has been replaced and has new gaskets when disturbed. All the work was done by my local service centre but he has now sold up and is moving away. A real shame for me but I am enjoying a having a go. It’s interesting you say that the carrier seal is the weak point. The machined face it pushes up to on the head could have been damaged by tools or clonking it with the cam. A small nick there would be enough I guess. If the spacers are not known to leak my attention swings back to seals, rings and gaskets. Cheers Ian.
Thanks for that Derek, very helpful and very interesting, I will give that a try. Even if it only stops the leak for a short time it may prove the point. Cheers Ian.
