My Catalac 900 has two Volvo MD2010's w/saildrives. The Starting instructions clearly state to hit the glowpligs for 10 seconds prior to turning over engines. When I brought the vessel over from England it was summer, so the engines started without any problem, however once winter set in the engines were extremely difficult to start. I powered the glow plugs many times and increased the time on them, still to no avail.
Once I removed the damaged glowplugs, I noticed that they had begun to swell on the tips which made them difficult to remove. The Volvo replacement glowplugs were $47.00 each. I needed two per engine. I found out that the NGK Y107V, are the same size and can be purchased for $8.00 each at an automotive store!!!
These glow plugs will also fit the MD 2040 engines.

My lesson learned is two fold: Research for compatable parts to save money, and NEVER hold the glow plug switch for longer than 10 seconds at a time. Cheers, Capt. Terry