J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Warm starting problem. Anyone run into this problem ?

My engine cools ok at low and high speeds and we had run about two hours. Tow vehicals have the same symtoms when run and worked hard. That is why you don't check radiators after shutting down to refuel a tow rig. You only open the radiator cap while idling or right at shutdown. The temp will go to the moon when a hot engine is first shut down. Clogging will show up under high speed running.

Since I unplugged the cooling passages, I have not seen a problem with the high temp light coming on after reducing rpm from a high speed run. Previously, I didn't get the alarm at high speed, only when slowing down. Now I don't get it at all.

I don't get an overheat buzzer when running, only when restarting after sitting for a moderate amount of time.

Ok Lake sailor. have you found the issue yet?
If not you seem to have a solenoid issue. this is common on cars.
the winding in the solenoid has a small fracture in it. it works when cold but when it gets hot the wire expands and separates.
we see this allot in ignition coils. outboard do it too when they run for five min and then quit for no reason and will not restart till cold.
The secret is that when you start it by jumping the terminals it is fine. so the only thing is the solenoid.
if you are good with electronics check for continuity in the solenoid contact with the wire off to the case or to the negative contact prior to starting. then do this again after it is hot when it wont crank.
the cold one should have resistance and the hot one should have none. this would mean you need a new solenoid.
or just take it to a starter shop and they will test it for you.
normally free because they hope to get your business.

hope this helps.

oh ya. Never ever and i mean just don't do it. Turn your Master switch off while the engine is running. This is how you kill the diodes in your alternator. As these engines use an older design not buffered it will kill the rectifier in the Alternator. but that's another story.

When you say never turn off the master switch, do you mean the key or something else?

He means the ignition key switch, but the master battery switch will also cause a problem. Don is correct - always shut the engine down with the fuel cutoff.

Using the key switch open circuits the battery from the charging circuit. In EE terms it tries to cause a rapid di/dt and since the current can't change instantaneously, the windings produce a voltage spike that can fry the alternator diodes.

This means my recently developed scheme to avoid the annoying alarm by turning the ignition key to off before pulling the engine stop knob is a bad.

Apparently I'm also abusing the engine by not idling for five minutes before shutdown. Is this necessary if the engine is only run at low rpm for the 5 minutes or so it takes to get in/out of the dock?

Definitely the alarm silencing approach you are using is not good. As soon as the engine stops, the turn off the ignition key. If you are fast enough, you'll beat the low pressure oil alarm!

Is Bebop fresh water or raw water cooled? If raw water cooled, you really need to cool the block at idle with no load to prevent deposits and scale. It's not as bad on a fesh water cooled engine, but if there has been any load, you are better off idling to remove the heat from the block.

Figured I would update this thread as the cause of all of my woe was finally identified, fixed and now the engine runs like a top.

After replacing and checking basically everything on the engine even remotely related to this problem and eventually working my way back and replacing the ignition as it turns out there is also a separate fuse wired just off the ignition - although I had replaced the fuse I had not replaced the fuse holder -naturally this turned out to be the problem - basically bad connections on the fuse holder. So long story short if you have a similar problem add this to your list of items to check.

Thx again to everyone for the help on this.