Catalina 27 Universal M-18 random not starting issue

[mforum]

In the last month, I’ve developed random starting issues with motor and am trying to trouble shoot it.

Start up sequence is batteries and then ignition to on (only off/on ignition), push/hold glow plug 20-30 seconds, then push starter button while keeping glow plug button pushed in. Once the engine is warm I don’t need to push and hold the glow plug button, just the starter button to restart.

Perhaps 20%-30% of the time when I try to start engine by pushing the starter button, I get a buzzing alarm sound with pressing and the yellow alarm light on the panel coming on. The engine does not turn over when this happens. Turn off ignition, battery, then back on… wait a few seconds, to a minute or so and it starts right up but does seem to have an alarm sound (I don’t remember before) when pushing the starter button.
I’m thinking this is more of an electrical issue than mechanical with starting. Batteries were replaced last year with 205 AMPHR AGMs and hold at about 12.59 V after 36 hrs with instruments/radio running and motor will start. I hear fuel pump running/fuel circulating when the ignition is turned to on. I replaced the starter button last year (because the old one was sticking after pushing in). Glow plugs as best I can tell were replaced last in 2014 but the starting alarm seems to happen after the engine is already warm or recently run, not after it has been sitting for a few days and starting cold.

The starter and starter solenoid and panel plug are on the port side of the engine behind the alternator (attached photo) in a very easy to reach position if you are the size of a leprechaun. I’m thinking to get a non-contact voltage meter and try to start checking voltages without having to do do a lot of disassembly or replacements if possible.

Any thoughts on where I should be checking first or what may be causing the starter alarm buzzer and engine not starting?

 

[kappykaplan]

From your description, I suspect a voltage drop at the starter. Try removing the electrical connections from the starter and cleaning. No ideas about your alarms.

 

[Ward H]

I agree with Kappy. Clean the electrical connections, including the ground connections at the motor and the connections at the starter .
You can also try releasing the glow plug button just before pressing the start button. The glow plugs will draw several amps when heating. Releasing the glow plug button first will allow those amps to be used by the starter to start the engine

 

[Stu Jackson]

1) Do NOT hold the glow plug button in when you hit the start. No need to have them both on at the same time.

2) There is a fuse in the wire from the start button to the starter solenoid, usually cleverly hidden behind the alternator. The fuse hold rots and you get nothing. Check it out and replace and relocate it.

While this stuff in the link is for a C34, it applies to most if not all diesel powered Catalinas and many other boats, too:

CRITICAL UPGRADES - DO THESE OR ELSE!!!

CRITICAL UPGRADES - DO THESE OR ELSE!!!

c34.org

 

[Richard19068]

1) Do NOT hold the glow plug button in when you hit the start. No need to have them both on at the same time.

I know on at least some M18's the glow button must be depressed to power the start button. It was the factory setup. Some, as apparently the OP's, have been rewired so the start button works independently from the glow button.
Maine Sail in his Compass Marine How To's said this about that:

"As you can see the key switch energizes the glow plug button first. There is then a "series jumper" that ensures the glow plug button is pressed in order to energize the start button. Personally I usually leave this series jumper in place as I have found owners will usually try to bypass the glow and not do it if they think they can get away with it. If you don't use glow, and the motor does not start, you are that much closer to filling your cylinders with water if the seacock was open.

If you feel brave and want to make the start button independent of the glow button simply move the jumper to the incoming side of the glow button, far right side, or jump to the outlet/on side of the key switch, far left. I don't advise this and do not even do this on my own vessel as I know I will try and take a short cut some day and it may cost me.

The yellow wire with red trace is the starter solenoid wire that energizes the starter. It is a tad undersized from the factory so with any resistance in the circuit, from trailer connectors or the in-line fuse holder, this can cause solenoid engagement issues. Once the trailer connectors have been removed, the wire re-terminated and new fuse holder inserted these problems often vanish even with the yellow/red wire.

As I mentioned there is an in-line fuse in the yellow/red wire close to the solenoid. This fuse holder is famous for disintegrating and ideally should be replaced when you do this upgrade. If you want to, feel free to run a new wire from the start button to the solenoid, 12GA is sufficient, and add a new in-line fuse holder.

It should be mentioned that the starter solenoid circuit is a low amp circuit. At max they pull about 2.3A +/- as measured on the "in-rush" or "peak current draw" for the circuit when hitting the starter button and capturing the in-rush with a Fluke DC clamp on DVM.. While the yellow wire can certainly handle the amp load for the circuit it is often the fuse holder or terminations that create enough resistance to cause even a low amp circuit like this some issues.

With some Universal engines I have seen the solenoid circuit wired with 14GA wire and some early ones with 16GA wire. The 16GA wire over a 20' round trip circuit, 10 feet one way, has about 1.6% voltage drop and the 14GA wire is about 1% voltage drop. If we extend the circuit to 20 feet one way, or 40' round trip we are at 3.2% voltage drop on 16GA wire and 2% voltage drop on 14GA wire. These are not bad voltage drop numbers but it you have the ability to re-use one of the other larger wires for this circuit, or run a new one, it will make your solenoid voltage drops even less."


Here is the diagram from the M12-M35 technical manual.

2) There is a fuse in the wire from the start button to the starter solenoid, usually cleverly hidden behind the alternator. The fuse hold rots and you get nothing. Check it out and replace and relocate it.

Good point. Also mentioned by Maine Sail in his info above.

 

[Ward H]

I know on at least some M18's the glow button must be depressed to power the start button. It was the factory setup. Some, as apparently the OP's, have been rewired so the start button works independently from the glow button.
Maine Sail in his Compass Marine How To's said this about that:

All good info. I've wondered if the practice of wiring the start button dependent on the glow plug button was a practice only for the M18 as most M25 series appear to be wired separately. Maybe the M18 was harder starting or more sensitive to hydrolock for some reason?

When I read Maine Sail's article on it back in 2019 or so, I thought about rewiring it that way to protect the M25XP when my wife started it. I decided on an easier but more costly approach. I made her my Ex. My current wife knows how to start the engine.