D311 genset started racing to high RPM

Dont run the set until you get the gov to work, overspeed can throw the windings in the rotor, Do you have a parts book to see where the gov springs are at? Its no big deal to replace the springs. If you are not schooled in govs. it might pay to have cat do the job....WA7OPY

First thing I believe you are misreading the serial number tag.

A D311 industrial engine series of that era that includes generator sets starts at 51B1-up. I have parts book covering up to 51B3139. It is very likely the series continued beyond 3139. Maybe OldMagnet has a serial number listing and possibly a parts book.

To start helping, we need pictures of the governor group. The ones shown in my book are two types of Caterpillar "basic governors" and some Woodward models. By the later series engines who knows what they had settled on as standard or were offering as optional equipment, but it is likely it isn't to different from these earlier ones.

The engine doesn't have a misfire on one or more cylinders does it? That would point toward an injection pump problem more than a governor problem. I realize a misfire is the least of your worries when an engine is overspeeding, but a stuck pump plunger will cause it. I recently dealt with a runaway D320 which is the turbocharged version of your engine. Since it hadn't been run in many years I was prepared to smother it by removing the air intake precleaner so I had a square cut tube to put a chunk of rubber belting over and cut off the air. I could control the rpm by varying the air intake while I loosened injector lines and determined which cylinder was missing so I knew which pump was stuck. Ended up pulling all 4 and cleaning everything up but it was nice to know which one was the problem. Of course choking off the air will cause it to smoke like an old coal fired steam train, but it might be deemed necessary for a short period even in California!

I hope you never had the occasion to get familiar with the operation of the safety shutdown system. The fact that you have to push it in or hold it in while cranking would seem to indicate that at least the oil pressure part is working since it trips when the engine shuts down. I am unfamiliar with the operation of those from the time of your set but they appear to be pilot operated valves that control oil pressure to overcome a "kill spring" force and keep the engine running until a fault occurs.

Oh, please post pictures of the boat and engine room etc. We don't get many boats on here!

Answering the request for boat pictures, here's one I did much work on many years ago
[attachment=49411]Horatia 2 x cat D336 engs 60B374 and 378.jpg[/attachment]

Answering the request for boat pictures, here's one I did much work on many years ago
[attachment=49411]Horatia 2 x cat D336 engs 60B374 and 378.jpg[/attachment]

[quote="catsilver"]Answering the request for boat pictures, here's one I did much work on many years ago
[/quote]
Catsilver, is it a life boat, harbor pilot boat or what. From the picture file names I gather it had twin D326 engines.

Since it over speeds it seems to me the prob is not the spring(s) but some kind of connection between the fly balls and the rack.