you will need a new battery, probably -- if it has been sitting any real length of time, the battery will be shot.

If you need one, get a Sears Diehard, International series. If your car isn't in the Sears book, get the one that fits a 1985 Volvo Turbodiesel, it's the same one -- huge. Make sure you ONLY use this battery in a 115 -- it has recessed connections, almost any other battery this big will dent the hood (personal experience....)

Check for fuel delivery at the bleeder on the fuel filter while operating the priming pump -- no fuel = no start.

Check that the motor turns at least 100 rpm -- it won't start if it doesn't.

Check for glowplug operation -- the resistor links on series plugs will get red hot it they are working, check for continuity on the parallel type. No glowplugs = no start. Please don't use ether, you can ruin the engine. Please!!!

If you have fuel and no glow plugs, you can use the hot air from a LIT propane torch aimed down the intake to help start -- DO NOT just blow propane in there, you can literally blow the head off (not funny, I've seen it done). The hot air (very hot, actually) from the burning propane torch will ignite the fuel spray and get you going.

Tell me what year this is and I can help more.

Low compression can be out of adjustment valves, nothing more -- more details if you need them.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!