I hav a 1984 Hunter 31 with a 2GMF Yanmar I'm sure the same age. She's hard to start when it just a little cold. I'm in St Pete so it's never really cold for any length of time. But even at 60 to 65 degrees she cranks and cranks, really hard to start. When it's in the 90s and no wind she starts right up... anyway if anyone knows any tricks or how to fix I would truly appreciate you shareing!
Yanmar 2GMF cold starting
- Thread starter Tom Fritz
- Start date
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,743
Hey Tom,
Has this been bugging you for a while and your getting around too try and solving the challenge, or is it a new occurrence?
Don't want you to feel this is 20 questions, but your query is one that may be the symptom of something else.
Has this been bugging you for a while and your getting around too try and solving the challenge, or is it a new occurrence?
- When was the last time you serviced the engine?
- Have you had the valves checked?
- Is your fuel fresh?
- Have you checked the air filter?
- How does the engine run when it is running?
- Any smoke out the exhaust?
Don't want you to feel this is 20 questions, but your query is one that may be the symptom of something else.
everything john said plus having the injectors cleaned and maybe the high presure pump serviced
Maybe ultimately. For now, start with the simple, minimum or no cost items and work your way up the $cale.
Please refresh my memory, is the 2GMF antifreeze cooled or sea water cooled ?
@Davidasailor26 sail has straightened me out re the "F" for the time being.
Of moderate expense ($5.00 for a gasket) is to check out the mixing elbow. It causes a host of problems if plugged. Hard starting could be one of them.
Hope that your elbow looks better than my old one :
Of moderate expense ($5.00 for a gasket) is to check out the mixing elbow. It causes a host of problems if plugged. Hard starting could be one of them.
Hope that your elbow looks better than my old one :
I had the same problem with my yanmar 3gm30f. The engine fired up instantly when it was warm. When it was cold it would crank and crank before starting. My problem was weak batteries.
Thanks everyone for your responses.
-The 2GMF has a heat exchanger using raw water to cool antifreeze.
-I installed a Stainless Mixing elbow about 6 months ago, hope it looks better than the old example right now.
-I did install new batteries recently. Thinking about adding heavier cables.
-When starting I do position the throttle at full speed.
John & Jon:
-I service oil, fuel filters, coolant, and transmission regularly.
-I have not cleaned the fuel tank but fuel seems okay checking at Racor. I'm 5 min. to the gulf so 15 gallons go a long way, I maybe add
fuel twice a year unless cruising.
-I do get some oil blow back around the air filter.
- No exhaust smoke.
-Runs good, especially for a 39 yr. old motor... I had her for the last 8 years after she was on the hard for 10 years. Early on I did have to
replace the rear seal and added a stainless sleeve as the shaft had rust spots around the seal. There's maybe a 1000 hours on the
motor. I really have no issues other than starting when it cooler tempers
I have not had the valves checked, injectors cleaned or high pressure pump serviced. Getting a mechanic out to the boat has been impossible lately. I will get with the local Yanmar dealer and try again to get someone out as I'm sure these type services haven't been done sense it left the factory.
I can always get it started, I just hate to crank it over for the period of time it takes to start her when it's cold. But temperatures around 60 degrees is not really cold. First start up of the day is the issue and any attempt after it cranks right up.
I'll add heavier battery cables, checkout valves, service injectors and high pressure pump. Thanks again everyone!
-The 2GMF has a heat exchanger using raw water to cool antifreeze.
-I installed a Stainless Mixing elbow about 6 months ago, hope it looks better than the old example right now.
-I did install new batteries recently. Thinking about adding heavier cables.
-When starting I do position the throttle at full speed.
John & Jon:
-I service oil, fuel filters, coolant, and transmission regularly.
-I have not cleaned the fuel tank but fuel seems okay checking at Racor. I'm 5 min. to the gulf so 15 gallons go a long way, I maybe add
fuel twice a year unless cruising.
-I do get some oil blow back around the air filter.
- No exhaust smoke.
-Runs good, especially for a 39 yr. old motor... I had her for the last 8 years after she was on the hard for 10 years. Early on I did have to
replace the rear seal and added a stainless sleeve as the shaft had rust spots around the seal. There's maybe a 1000 hours on the
motor. I really have no issues other than starting when it cooler tempers
I have not had the valves checked, injectors cleaned or high pressure pump serviced. Getting a mechanic out to the boat has been impossible lately. I will get with the local Yanmar dealer and try again to get someone out as I'm sure these type services haven't been done sense it left the factory.
I can always get it started, I just hate to crank it over for the period of time it takes to start her when it's cold. But temperatures around 60 degrees is not really cold. First start up of the day is the issue and any attempt after it cranks right up.
I'll add heavier battery cables, checkout valves, service injectors and high pressure pump. Thanks again everyone!
You could add an air intake heater, there may be one that fits the 2GM but here's a generic one: https://www.summitracing.com/parts/smp-dih1
Saw this comment:
"Our 2GM20F was hard to start cold... We added a cetane booster, it made a world of difference. Apparently US diesel has minimal cetane, the booster will help a lot."
Good read on the engine, talks about hard starting:
saltwaterdiesels.com
Thread with some suggestions:
Saw this comment:
"Our 2GM20F was hard to start cold... We added a cetane booster, it made a world of difference. Apparently US diesel has minimal cetane, the booster will help a lot."
Good read on the engine, talks about hard starting:
Yanmar 2GM Series Marine Diesel Engines - SaltWaterDiesels
Yanmar 2GM20 Marine Diesel Engine service guide. Maintain, troubleshoot and fix your 2GM. Winterising & Maintainance checklists. Advice from owners.
saltwaterdiesels.com
Thread with some suggestions:
Yanmar 2GM...re: cold starting...
After reading several threads on the 2gm...has anyone found an easy way to cold-start a 2GM??? Yes, I'd checked all of the filters, and, they are clean. Once the engine is warm, it starts right up. There is no glow-plug on this engine...a friend of mine just suggested a very short squirt of...
forums.sailboatowners.com
Always look for proof before spending a damn good whack of money like that and getting nothing for it. See my post #5 :
You sound like you know your way around an engine and are doing the work yourself, so check out your starter cables :
1. Measure the voltage of the batteries which will be supplying power to your starter motor. They should be about 12.8V. If not, charge them up.
2. Now attach the voltmeter to the two contacts on your starter motor. DO NOT connect them to the starter solenoid as that's not what you're after.
3. Have someone crank the engine and note the voltage on the voltmeter.
4. If your cables are in good shape and have low resistance, you're voltage will drop no lower than about 12.0V.
Let us know what you get.
PS. Stay away from the high priced stuff for now.
A couple of further thoughts :
1. What is the AWG size of the cable leading to your starter motor ?
2. If you do show low voltage when starting, the first thing to check is every electrical connection between your batteries and starter motor. Look for corrosion and loose connections.
Last edited:
Many good suggestions above…
My go to suggestions are to:
- Make sure batteries are charged and wiring is sound, tight and not corroded.
- Throttle to about 1/2, try to start. If it doesn’t catch…
- close throttle, turn engine over a few times to warm up cylinders, then throttle to 1/2 and see if she starts.
- If really cold out, warm up air intake somehow…hairdryer or heat gun if you have power. Hold a lighter down there if no AC power. Then try to start as normal.
- If she doesn’t turn over easily, try opening the decompression levers and turn it over. If you have help, once spinning over, close compression levers and add throttle.
-Do Not turn the engine over too long if it doesn’t catch. You don’t want to hydro lock the engine. Remove thimpeller or close water intake valve if troubleshooting and you have to crank it for a while.
-If she starts, but then dies, probably a fuel issue (dirty fuel, plugged filters, or air in the line).
If you suspect bad fuel, try using a gas can with fresh fuel and pull fuel from there instead of the tank. Check fuel filters too if you suspect a fuel issue.
It only takes three things for these older diesels to run…fuel, air, and heat/compression. The 2GM20F doesn’t have any electronics to speak of.
Greg
My go to suggestions are to:
- Make sure batteries are charged and wiring is sound, tight and not corroded.
- Throttle to about 1/2, try to start. If it doesn’t catch…
- close throttle, turn engine over a few times to warm up cylinders, then throttle to 1/2 and see if she starts.
- If really cold out, warm up air intake somehow…hairdryer or heat gun if you have power. Hold a lighter down there if no AC power. Then try to start as normal.
- If she doesn’t turn over easily, try opening the decompression levers and turn it over. If you have help, once spinning over, close compression levers and add throttle.
-Do Not turn the engine over too long if it doesn’t catch. You don’t want to hydro lock the engine. Remove thimpeller or close water intake valve if troubleshooting and you have to crank it for a while.
-If she starts, but then dies, probably a fuel issue (dirty fuel, plugged filters, or air in the line).
If you suspect bad fuel, try using a gas can with fresh fuel and pull fuel from there instead of the tank. Check fuel filters too if you suspect a fuel issue.
It only takes three things for these older diesels to run…fuel, air, and heat/compression. The 2GM20F doesn’t have any electronics to speak of.
Greg
Yanmar engines use exclusively compression to heat the air fuel mixture to its flashing point. A cold start engine builds compression through successive engine revolutions as turned by the starter. To attain the adequate amount of compression the engine needs to turn fast enough. Cold temperatures present two obstacles 1) cold thick oil which adds friction and resistance to the cranking components and 2) starting at a lower temperature the air fuel mixture is required to bridge a higher temperature gap. In extreme cold temperatures the battery output can be curtailed when most needed. What to do? Insure your engine is cranking as fast as it can. 1) make sure the starter and the battery are in good health, battery should be fully charged and the connections tight and clean, 2)open the throttle while cranking, that will allow more air flow through the intake tube ( any blockage in the exhaust mixing elbow or muffler can curtail free air flow) 3) in the winter use a multigrade oil which does not exceed 15W at the lowest temperature range. In extreme temperatures some use heaters in the engine compartment but in Florida there should be no need. Good luck.
I have never seen a diesel with a throttle valve in the intake. Opening the throttle does nothing to increase air flow in a diesel, it does increase the amount of fuel injected. It however does help with cold starting.
Anything that increases cranking speed or heat in the engine will aid cold starting. Compressing air heats it, the heat is what ignites the fuel.
IIRC Dodge and Cummis did a study in the 1980s on starting cold diesel engines. If you can find it it's worth reading. What I took away form the article was to make sure to 1) use the correct oil in low temperatures 2) healthy starting battery 3) large starter/battery cables 4) use an block heater if possible 5) make sure the glow plugs are working correctly (if equipped).
Anything that increases cranking speed or heat in the engine will aid cold starting. Compressing air heats it, the heat is what ignites the fuel.
IIRC Dodge and Cummis did a study in the 1980s on starting cold diesel engines. If you can find it it's worth reading. What I took away form the article was to make sure to 1) use the correct oil in low temperatures 2) healthy starting battery 3) large starter/battery cables 4) use an block heater if possible 5) make sure the glow plugs are working correctly (if equipped).
@SycloneDriver , from what I've been able to find, a diesel is constant air intake. Does this affect combustion in any way as you go from very high excess air at low speed to low excess air at WOT ? Any idea how much is the excess air at WOT ? Thanks.
Off the top of my head. I think it is as lean as 35:1 at idle and closer to 12:1 at WOT. Don't quote me on those numbers. A diesel will smoke if it isn't getting enough air for the fuel delivered. In EFI diesels there is a fuel table often referred to as a smoke map. The ECU will not inject additional fuel beyond the smoke threshold.
One easy thing that can be done for a hard to start diesel is to add a fuel supplement containing a cetane booster.
Unless you are operating your boat well below freezing skip the winter additive and use the standard one. The antigell agent wouldn't do you any good and it will contain less of the injector cleaner and cetane booster, this info is from the manufacturer.
Unless you are operating your boat well below freezing skip the winter additive and use the standard one. The antigell agent wouldn't do you any good and it will contain less of the injector cleaner and cetane booster, this info is from the manufacturer.