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Discussion Starter · #1 ·
the GM 30 in my Catalina 30 has always been hard to start. I thought I took care of the problem last year when I replaced the mixing elbow and removed the fuel injectors and had them repaired and re calibrated. One of them had a totally broken spring.

It still takes around 30 seconds or so on a couple of starting sessions (no more than 15 seconds at a time) to get it going. Once it does start and runs for a bit, I can stop it for a good period of time, like when I day sail for 4 o4 5 hours, and it will start right up in a couple of seconds.

Is this normal behavior, or is there something else I can check. I am guessing the next step will have to be a compression test of the cylinders, but I don't have the equipment for that yet.

anyone have any ideas? I am really jealous of those whose engines start right up, any time....
 

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Discussion Starter · #3 ·
Not sure what you mean, but I did replace the half orb thing at the bottom with the hole in it (I know, very technical jargon... lol a mechanic I am not) in all 3 chambers with a new one...
 

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Are you using a full throttle position when cranking? My understanding is that that works best when starting some Yanmars.. of course be ready to throttle back as soon as she catches.
 

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Closet Powerboater
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I'm interested to see what is the cause here too. My Perkins 4.108 was this way. In particular, in the cold, it would take several 15-20 second bouts of cranking to start. Yet when warm, it would fire off, with the throttle in the idle position, instantly like a car.

I suspect it was compression, but I sold the boat and never found the true cause. Of note, when I sold the boat the starter died shortly thereafter. A starter that isn't spinning the motor fast enough could be part of your problem.

I also wondered if the heat was making the oil thinner (as it does) and thus making the flywheel easier to spin fast enough to start. To treat the symptom, and to buy time, I put an oil pan heater on the motor and would operate it for 30-60min prior to starting. I knew it wasn't addressing the real issue, but it sure did make for a nice Band Aid. I wondered if a multigrade oil like 10-30 or 10-40 (Delo for diesels) would also ease starting, but never tried it.

Here's the one I used. Draws 20A at 12v. 12V Oil pan heater Wired to a simple breaker (which doubled as a switch) with large wires from the battery

Other things to check are that you have large enough, and healthy enough batteries for the task. The wires to the starter, and from the ground to the battery, should be large and free of rust. The starter should be in good shape. You've already addressed the injectors, so compression is where I would look next.

How old is your engine? Does it have any other symptoms? Can you reach WOT while underway? Any smoke at startup or otherwise?

MedSailor
 

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Agree with Med, keeping things warm will help tremendously. We used a little 250W plate heater that simply kept the engine compartment warm.. even a light bulb will help.
 

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I'm assuming this is a 2GM or 3GM. These engines do not have glow plugs to aid in cold starting. As Faster noted, you need to give it some throttle when starting cold. I give my 3GM30F about half throttle and that usually results in a start within 5 seconds. And as noted you need good batteries and starter so it cranks quickly enough as the heat to ignite the fuel comes from compression.
 

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Discussion Starter · #8 · (Edited)
thanks for all the responses.

I forgot to mention that I had replaced the starter last year as well. in an unrelated project, I have replaced the batteries, and all of the battery wiring to bigger sizes.

I have not tried advancing the throttle. I will do that tomorrow and let you know if that makes any difference. the heating plate is also an intriguing idea. someone told me once to use a hair dryer or heat gun into the air intake to warm up the cylinders, but I never actually did that. I always felt that if my 3GM30 had glow plugs it wouldn't be a problem, but alas. actually the first time I had explained that it DIDN'T have glow plugs I was in a state of disbelief, until they explained how combustion actually happened in diesels...
 

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al brazzi
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My Volvo has a primer lever you pull from the key position. It works well on cold starts but since September they have all been cold. If you have a compression release you might try opening it to get a good spin on the engine unloaded of compression, and its a good indication of compression when its closed. I would try and see if that aids starting.
 

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Irrationally Exuberant
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Not just advancing the throttle...full throttle. And as Faster said, be ready to pull it right back. Definitely helps in cool/cold starts.
 

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Hey,

Don't feel bad. It's the nature of diesels that they just don't like cold weather. Unlike a gasoline engine, with a spark to ignite the fuel - air mixture, a diesel relies on the heat from compression to ignite the fuel - air mixture. The colder the ambient temperature the higher the temperature needs to be RAISED before combustion. That's why glow plugs help - the purpose is to raise the temperature inside the combustion chamber so it's easier to get to combustion temperature. That's also why starting fluid works - it ignites at a lower temperature.

After the engine been run for a period of time, and everything is nice and warm, it will be east to start even a few hours alter because the iron block tends to hold the heat for a long time.

Barry

I have not tried advancing the throttle. I will do that tomorrow and let you know if that makes any difference. the heating plate is also an intriguing idea. someone told me once to use a hair dryer or heat gun into the air intake to warm up the cylinders, but I never actually did that. I always felt that if my 3GM30 had glow plugs it wouldn't be a problem, but alas. actually the first time I had explained that it DIDN'T have glow plugs I was in a state of disbelief, until they explained how combustion actually happened in diesels...
 

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Courtney the Dancer
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Our last boat (my brother's current boat) had the same engine and the same starting difficulty. It never fired right up even when new, but did gradually get worse. Different throttle positions made very little difference, although we settled on about 1/3 to 1/2 as being the most reliable. The one thing that did make a big difference was adding a cetane booster to the diesel. I'm not an expert but the new low emission diesel just doesn't seem to fire up as well in older engines. We also had the injectors rebuilt which helped a little, but the cetane booster really helped a lot. One other thing that helped in very cold weather was cranking the starter for 15-20 seconds or so with the stop cable pulled out and then pushing it in while continuing to crank the starter. Usually fired right up doing that. Good luck.
 

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One more vote for full throttle on cold start. One thing to be aware of when you do that is the big puff of black smoke that you should expect to see out the exhaust. The full throttle injects excess fuel and the black smoke is mostly from unburned fuel. This is nothing wrong, just the norm. On my 3GMD, it starts within 2-3 seconds at anything above 50 degrees, and the black smoke is gone within a few seconds of running. I have no idea how it would start at colder temps, as I am no longer a cold weather sailor :)
 

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I'm still getting the feel of my new-to-me 3gm30f. In the winter when temps were in the 40's during the day it was full throttle to start her. Now that it's warmed up to 50's-60's in the day it's only half throttle required. It depends on how well charged the starting battery is too. It usually starts pretty quickly unless I don't give it enough throttle. Then I just push it ahead and away it goes.

My engine only has ~100 hours and that may matter, too. The engine sat for a few years so it's barely broken in.
Mike
 

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My 2gm and a previous one started fine in the sub tropics. In fact the earlier one (13 hp)could be hand started if accompanied by sufficient desperation and bad language. But this one is the later 16 hp and no way can I swing it past compression to start it. Also, I am older and not as strong now.
But anyway, when I moved to Tasmania I found it was a ***** to start from cold.
So.....having picked it up from either this website or similar, here is the 'Alaskan' method to start a non glow plug Yanmar:
With cooling seawater valve CLOSED and throttle IDLE , crank it for 10 seconds. That seems a long time, but the idea is to build some heat into the head with compression while not allowing water in to the cooling system - or worse, the manifold, or even worse, the cylinders.
Now, without delay, cooling seawater OPEN, throttle fully OPEN and it should start with about 5 seconds of cranking. Be ready to smoothly reduce throttle as it catches to avoid over revving.
The original 10 seconds of cranking will have established some oil lubrication, so even if you are a bit slow reducing throttle you shouldn't hurt it. I let mine warm up at a fast tick over (about 1200 rpm) while I go back to make sure water is flowing out the exhaust. Pulling it right back to slow idle too soon may cause it to cut out in really cold conditions.
 

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Further to the above, carry a spare starter motor! Even an el cheapo non OEM is good insurance. I put one in a locker and had almost forgotten it was there and sure enough, the original burned out after about 5 years.
It is a 20 minute job to do the change. I have had the original overhauled for when El cheapo croaks.
 

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My 3GM30 with 2,500 hours starts cold in a few seconds in idle RPM in hot or cold weather (winter here can get fresh, but hardly cold- maybe 15 degrees celcius). I've never had to to give it throttle to start. Have you checked the compression of your engine?
 

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Over Hill Sailing Club
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My 3GM30F is hard to start when below around 45 degrees. It always has been, even after re-ringing, so low compression is likely not your problem. When it's cold (and I am aboard), I make sure to open the engine hatch so heat from the boat can get into the engine compartment overnight. This definitely works. The throttle needs to be wide open, quickly backed off when it starts. Also, if you can put house and start batteries all to work with the battery switch, it helps when cold.
 

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The one thing that did make a big difference was adding a cetane booster to the diesel. I'm not an expert but the new low emission diesel just doesn't seem to fire up as well in older engines. We also had the injectors rebuilt which helped a little, but the cetane booster really helped a lot.
One of the bits of info from the Mack Borings owners workshop..Cetane rating for domestic diesel is barely minimal rated to around 40 as compared to European standards of about 45.

Follow the Yanmar workshop recommendation of full throttle to start a 3GM30F in cold temps.
 
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