Great tips Randy. I'll add a couple non-Volvo tidbits that perhaps you could comment on for sake of Volvo-world clarification.

1. Ground the coil wire? I noticed you said remove but in other types of cars I have heard grounding it is appropriate. Is this the case on Volvos too?

2. Disable fuel injection? I didn't notice you mention this and having the fuel injection dumping fuel in while running a compression check can also skew results. In the case of Audis (the cars I do know pretty well....I'm in my Volvo learning curve mode now) I simply remove the fuel pump relay since it is easy to get to in the engine compartment. I am curious what you suggest on a Volvo, specifically a 1983 240 turbo.

I tend to be pretty lax on doing compression tests. I find that engines that start easily, run well, don't smoke, have appropriate power don't fail a compression check (at least all that I have tried over the years) so I sorta relegated it to being a troubleshooting tool rather than maintenance check. Perhaps I am being lax and my experience there is bad advice to offer though.

I will run one on the '83 turbo though since I do want to get an idea of overall health prior to adding an intercooler and bumping up the boost.