Valve Stem seals - Easier way to change them?

I may be buying a Volvo 850 T5, with a problem. It smokes. It is fine for around 5 miles of it being initially started and then it will start to smoke. The smoke will die down a little when revved a bit, but besides that, it smokes a Blueish smoke, but the HG seems to be fine. He has changed the turbo for another one (admittedly, one off ebay), but to no avail it still smokes. Oddly enough it happened after he changed the waterpump, which got a little rattly, although it did not overheat etc. I am beginning to wonder if it is the Valve guide seals or the Turbo. From past experience I have changed the valve guide seals on an Escort XR3i with the CVH engine using the Sykes-Pickett tool which circumvents the issue of taking the head off. I have looked through this forum via the search function about the job involving the stem seals but the posts are pretty old (2003). I was wondering if it still required the head to come off and if it is indeed a very pricey job, or if there is a tool now to allow you to change the head in situ. I will be running a compression check on the car if I buy it. Cheers.

I did leave off a few details I admit, so I think a rectification is in order :). The car is an M reg 1994 850 GLT T5 with 188,000 miles on the clock. When I said it didn't smoke for 5 miles, I meant 5 minutes. However, it only started to smoke since the waterpump was changed, from which before it was fine. From what you say, it does seem to point to the turbo, even if the turbo has been changed I guess. What else do you think it could be besides the turbo?

Its most unlikely to be the valve seals on a volvo engine . Pull back the front pipe from the turbo see if it is damp with oil on there, coating the inside of the pipe or the exhaust turbine blades .

There has been talk in the past of fabricating a tool to support the valve from within the barrels to enable you to hold the valve shut enabling you to work from above however i would draw you attention to notice... However i have certainly heard of projects to fill the bores with compressed air via the sparkplug hole to hold the valves shut with the cams removed..... Cheers Jod

A method of holding the valves closed which I have used with success many times and does not need compressed air. Piston half way ( roughly ) up the cylinder on compression stroke. This is important as both the valves are shut. Get some thin rope and push about 5-6 ft into the spark plug hole leaving enough to pull the rope out again. Turn engine so as to crush the rope against the valves.Remove the springs, change the seals. Refit springs. Turn engine BACKWARDS and remove the rope. Pookie