Yanmar 2GM20F cold starting

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prdewolf

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Jun 22, 2005
20
Hunter 310 Virginia Beach, VA
My Hunter 310 Yanmar has always had problems cold starting. I can crank the engine for long periods (careful with the water lift muffler) and have no success. A few years ago I read about injecting hot air in the intake and I used a heat gun to do so when cranking and the engine fired right up immediately. My question; Is this Yanmar just difficult to start cold or am I not doing something to get it started?:confused: Unforunately I don't have 110AC when I am out on the water and therefore the heat gun is not an option. When it's seasonably warm, there's no problem staring.
 
seadaddler

seadaddler

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Dec 19, 2006
5,812
Hunter 36 Punta Gorda
When

When was the last time you checked your mixing elbo,I did have cold starting problems once in a while but I must tell you when I cleaned out my mixing elbo the engine ran better than new.
What I did was take the mixing elbo off and the two parts apart and than used different types of pointed chisels to clean out the coke build up,some thing like a ice pick and heavy pointed screw driver,you would not believe how small that passage gets withe the black coke in there and cuts down on exhaust and causes black flow and could also cause hard starting.
Just my suggestion to try,mixing elbo's should be checked before they get to the point where it has to be replaced$$$$$,I found cleaning is good for the engine and will save having to replace.
Nick
 
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Steve Dion

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Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
We had a 2gm on our '85 H'31. It would usually start within 10-20 seconds even in the winter. When the weather was warm the engine would start almost immediately.

Do you advance the throttle when starting? Check for air-leaks. Check that mixing elbow like Nick suggested. If you have reused any of the banjo washers you may have an issue with fuel leaking down in the system.

You may also want to have a mechanic that is certified on Yanmars to take a look at it. It is sometimes the best $100-200 you can spend.
 
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Steve Dion

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Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Hell if I know! <g>

Quoted from (http://forums.torresen.com/sailing/viewtopic.php?f=2&t=2903)

"In the mean time - if you have access to electrical power, try
putting the output of a hair dryer into the air inlet on the
engine for a few minutes before the first start of the day. It
can work wonders, but it won't correct your problems.

Hard starting can be attributed to a number of reasons, including
compression, HP fuel pump, fuel, air intake, injector, injection
timing, etc."

Good luck, we would like to find out what you find out!
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
diesel 101

diesels are compression ignition engines. They compress air to heat it hot enough to ignite the fuel when it is introduce at the injector.
It may sound silly but cold air is harder to "get up to ignition temp" than hot air.
This is why some diesels have glow plugs. The cold engine metal sucks up a lot of the heat generated by compression and turning on a heater at the top of the combustion chamber helps get to the needed temp for a start.

A hot air boost start may mean that you are not getting enough compression for a cold start, you are cranking to slowly, your air filter is clogged or you exhaust is clogged. All these things cause either a lack of heat or less air (and less compression) to enter the engine.
There is also the injector spray pattern. A drippy pattern is not going to be easy to ignite till the motor is good and hot. A very fine spray pattern (ideal) will form a fog of fuel that is much easier to ignite.

I'd check the following:
engine cranking speed cold and hot
compression pressure
air intake restricted
exhaust restricted
injector spray pattern

It might also help to let the engine compartment warm to cabin temp before trying to start. Also don't crank the starter for more than 15 seconds at a time and 25% duty cycle or it will heat its windings and fry.
 
Warren Milberg

Warren Milberg

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Dec 1, 1999
2,391
Hunter 28.5 Chesapeake Bay
Without glow plugs, I really think Yanmars are cold-hearted beasts. My 2GM20f starts quiickly on most days when I want to sail. But when the temps get low, I've used a hair dryer to let the engine suck up warm air, as Bill suggests. Since you don't have 110AC, you may want to buy a small DC hair dryer or heat gun, if needed. Or use a small inverter with a 110 ac unit.

Another thing that might help, assuming all else is well with your engine, is to shut off the raw water intake, throw the decompression levers, and crank the engine for a few seconds once or twice. This will bring a little fuel into the cylinders and get the pistons lubed a bit. It may also warm the cylinders a bit. Throw the levers back, open the raw water intake and hit start. Worth a try.
 
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