Blue smoke when backing off - 944

[Guest]

I get a plume of blue smoke when slowing down and sometimes when changing gear. (1985 944) My local mechanic suggests its valve stem seals, and is confident that he can replace these without removing the head. I thought the only way to do these was to take the head off. Obviously it will be great if he can do it that way but although the mechanic has been recommended to me, Ive never used him before....what do you think?

 

[John Sims]

Whilst I don't know on the 944 specificaly the valve stem seals are rubber gaiters around the stem of the valve (funny that) so you could perhaps change them with the head in situ. My main worry would be if you dropped a valve into the cylinder (if this was possible) it might be tricky to retreave.

In truth, I don't know if it is possible or not.

As a possible cheap fix - Wynns do an oil additive which softens old rubber seals to help stop the problem you mention. Wynns did a presentation at our regional club night recently and seem to know their stuff. It may not work but for less than £10 it could be worth a go.

 

[Guest]

Thanks very much for the reply...i'll have a look around for the Wynns stuff and give it a go

 

[944Turbo]

I would have thought it could be a combination of stem seals and valve guides, so worth getting the guides checked at the same time. Stem seals only might just be a temporary fix.For piece of mind I think I would have the head off, but I might consider the oil as upper cylinder lubricant for a while unless it is really bad []
Tony

 

[924nutter]

Valve stem oil seals can be replaced in situ. I would line up all the timing marks and then lock the engine in position. Once the cam-box is removed all the valves will be closed. Then, the trick is I believe, to fit an adapter into the spark-plug hole and pressurise the cylinder with compressed air to hold the valves against the seats whilst removing the collets.