Universal M25 problems

[John Visser]

Coincident with a high-temperature event (clogged heat exchanger) my M25 developed a lower idle speed, 600 RPM rather than the usual 700. Runs rough and shaky at 600. I don't think the temp ever went near dangerous, so I'm thinking this might be unrelated. I consulted a troubleshooting book, and the engine manual, and conclude that I must have a worn-out or bad injector. The transom usually collects a sooty coat in use, since I've had the boat (1.5 years). I have no reason to believe hte injectors have ever been replaced or serviced. Total time 2000+ hours. If an injector needs service, they probably all do, is my thinking. Comments?Thanks,jv

 

[Pete]

reset the idle

John, since no one else has answered I will try.I'm not sure on your engine how to do it,but reset the idle to 700 rpm. On the yanmar there is a simple cable screw adjustment. The idle speed may or may not be conected to your recient overheating. If it still runs rough it would be tell tale to to having the valves and injectors reset. It could also be a bad injector(slow speed miss)spray pattern and you may need new a injector unless you are a very good mechanic I would suggest you get it looked at by a good mechanic. I think you are on the right track here if a second opion is worth anything. Good Luck and post a respone as to what was the final results! Pete

 

[John Visser]

Thanks

Thanks for the reply. I won't reset the idle, adn I'll explain why. 1. On my engine, the speed control stops, on the speed control lever are wired in place after factory adjustment. They are not meant to be adjusted. 2. The loss of idle speed was relatively sudden, not gradual - meaning, its not from long term wear, but from some component or system fault.3. Peter Compton's excellent marine diesel troubleshooting manual indicates only a fuel restriction, as form clogged filters, or a faulty injector as among the probable causes of low idle. My filters are clean - less than 100 hours of running on them, with a new fuel tank and new fuel. I think I just puished an injector over hte edge. The exhaust has been somewhat sooty since I got hte boat 1.5 years ago. 4. I have no reason to believe the injectors have ever been replaced or serviced, in over 2000 hours of running time. Some suggest 800-900 hours between rebuilds, the USN does it every 1500 on continuosly run (generator) diesels. I assume intermittent running is tougher on them. So, that's my reasoning.I located NEW injectors at less than the cost of rebuilding the old ones, and assuming I got hte right part, I'll be replacing the injectors this weekend. I got the part by learing the manufacturer's part number of the injectors, and purchasing from a diesel engine parts company. I'll let you know what happens.jv