Posted: Mon Sep 20, 2010 5:06pm

For a few months now my BMC 1.8 engine has been giving off puffs of white smoke when at tick over. This is most annoying in locks where the smoke accumulates, but not a problem on the open water. We have had the fuel filters changed, had the injectors reconditioned and changed oil and filters. The engine is otherwise mechanically sound. Our engineer has suggested it may be because of low compression or a problem with the diesel pump. I'm not sure whether to spend some more money trying to get it sorted or just to put some Fuelset in the tank when I next fill up. Any ideas?

Posted: Mon Sep 20, 2010 5:50pm

If your mechanic thinks it might be a low compression then why has he not done a compression test to prove/disprove it. It might be a tight valve clearance. I would not immediately assume its the pump. It could even be steam caused by a slightly leaking head gasket or a slight internal crack so keep an close eye on the coolant level. I would use Marine 16 and also give the boat a good thrash if you can get it on a river. When it is doping it try slackening each injector union in turn and see which one makes the least difference or stops the puffs. That will tell you the faulty cylinder. I would also want to see the invoice for the injectors from an injection equipment specialist because it is not unknown for engineers to "overhaul" them on a simple pop-tester and that will not test the auxiliary spray hole that may come into play at low speeds. However its usually at cranking, not idle. Tony Brooks