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Starting diesel in freezing temp....

NYSail

.
Jan 6, 2006
2,603
Beneteau 423 Mt. Sinai, NY
Hello all.

Having a survey done on boat this coming weekend and weather looks as if it will be cold. I have a Yanmar 3HM35F.... always starts immediately on first press, however never attempted in the freezing cold. Should I use decompression valve and spin engine manually a few time to get oil circulated prior to starting? Engine does not have glow plugs so fuel going in will be COLD. Any suggestions / advise would be much appreciated as I don't want to harm the engine. Buyer will be buying new antifreeze to re-winterize when finished.

Thanks

Greg
 
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Likes: ALNims
Nov 6, 2006
8,866
Hunter 34 Mandeville Louisiana
Some folks have reported success by using a heat gun to heat the intake manifold to 100F or so then remove the air cleaner and point the gun into the intake while cranking.
 
Jun 3, 2004
886
Hunter 34 Toronto, Ontario Canada
We often end up starting engines in low temps at launch in this prt of the world. I put a little space heater in the engine compartment and run for an hour or so . Starts like summer.
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
The decompresson valve on some diesels are for starting it.. you can pull the lever and spin the motor (5-8 seconds) until you hear a change in sound and then push the lever in quickly while still cranking... this puts fuel in the cylinders, causes a slight bit of heat, and gets the oil up in the engine...
 
Jan 4, 2006
3,147
Hunter 310 West Vancouver, B.C.
I have a Yanmar 3HM35F.... always starts immediately on first press, however never attempted in the freezing cold.
One thing I've noticed with our Yanmar is that it always starts in the first 1/2 rev. if the cylinders are wet from running within the last day or two. And that's been in some really nasty cold weather.

If you've got someone coming to look at the boat, try running the engine for 30 seconds sometime before the prospective buyer shows. Shut it down cold so the oil sticks to the cylinders.
 
Apr 14, 2009
727
Sabre 28 NH
I know some will snap about this, hahaha
Give it a shot of WD40 at the air intake.
That's what the big boyz use in the winter to get things started.
Safer than using either.
 
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Likes: All U Get
Dec 31, 2016
315
Beneteau Oceanis 351 Charlottetown
One thing I've noticed with our Yanmar is that it always starts in the first 1/2 rev. if the cylinders are wet from running within the last day or two. And that's been in some really nasty cold weather.

If you've got someone coming to look at the boat, try running the engine for 30 seconds sometime before the prospective buyer shows. Shut it down cold so the oil sticks to the cylinders.
Hmmm, not so sure this would be the way to go. When we bought out 351 ,I insisted on being there to see the engine start cold. A few problems starting a cold engine can't be observed starting a warmed engine. I'm sure the buyer would understand it's not going to start the same cold as it is hot,and I'm sure the surveyor would pick up on the engine being warm as well.
 
Oct 30, 2011
542
klidescope 30t norfolk
+1 space heater open engine access panel set heater in or near space to pre warm block and intake air
 
Last edited:
Jun 6, 2006
6,992
currently boatless wishing Harrington Harbor North, MD
Well if he wants to see the motor start on a freezing cold day that is kinda dumb. Probably wants to see it start on what would be a normal sailing day temp with engine "cold" I'd be leaning toward the space heater as "you will need that while waiting for the surveyor".
 
Sep 17, 2012
74
Morgan 383 Fairhaven, NY
Space heater to heat engine and air around it. Longer is better. Diesels need to heat air to fire. Warm air engine room air helps. Make sure your battery is charged. It'll take some cranking. And probably run like crap until it warms up a bit.
You will destroy your raw water impeller unless you take some action to prevent that from happening.
 
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Likes: BrianRobin
Nov 29, 2012
34
Can't commend this, but, ..... back in college in Colorado, when it was -20, and God was just a child, I would use a squirt of ether in the carb. And boom! My old VW would start right up. (Who could afford an engine block heater?) So the air intake might work similarly. But can be dangerous on a boat.
 
Mar 19, 2014
1
Saltram Pocket Sloop Arbroath
24V your starter motor by wiring 2 batteries in Series. Scares the s!*t out of people.
 
Jul 26, 2015
42
Watkins 29 Ft. Lauderdale
Take this for what its worth from a guy who lives in Ft. Lauderdale, but Ive got friends who sail in the frozen north...somewhere north of Jacksonville, Fl. and they put a 150 watt light in the engine compartment every night... it generates enough heat to keep the engine warm enough to start.

Blowing a heat gun into the air intake might help but understand that air will have considerably less density and oxygen molecules...the engine will start in a very rich condition and probably smoke like hell.
 
Oct 24, 2015
30
Hunter 356 Brightlingsea
As the engine is so cold it will take awhile to get the combustion chambers to warm enough to fire the diesel. The longer you crank the engine the greater chance of filling the exhaust with sea water & it getting back into the cylinders.
Cranking the engine with the decompressor engaged will not warm/heat the combustion chambers.
The really simple way is to remove the intake filter & use a cigarette lighter at high setting just at the intake whilst cranking
, it will be enough to raise the temperature to enable an easy start.
Any surveyor will know that a non-preheated diesel will be reluctant at that low temperature.
It will help to have the "throttle " a couple of inches open with the gears disengaged so that the engine will continue to run once started.
How quickly the engine starts cold is a good indication of it's health.
Neil
 
Jun 6, 2016
157
Catalina 275 Wilmette, IL
Placing a incandescent drop-cord light under the engine the night before should give it a little warmth. Blanket over the engine would be a bonus. As the drop-cord can get warm, make sure it is not resting on anything that can get damaged by heat.
 
Oct 26, 2008
4,570
Catalina 320 Barnegat, NJ
It's been so warm, I'm wondering why you are worried about this. 60's today, 70's tomorrow. Is your boat in the water? Why not just start it a few days this week. Granted, it will be colder over the weekend, but we aren't having winter. It will be in the 40's. If you've had your boat running this week, you should have no problem over the weekend.

and why bother with the re-winterization? It's March tomorrow. We haven't had winter yet this year, so I doubt it's going to happen in March. I'm thinking about prepping this weekend to see how soon we can be put in the water. We could have sailed right thru the winter this year, probably without any need to winterize if the boat was in the water.
 
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Likes: ITMaster
Nov 2, 2008
107
Beneteau 331 Chicago (DuSable)
Appreciate the replies so far but I'm curious as there is some missing info.
"Cold" is a relative term. What is cold to us really is not so cold to our beloved engines.
Also do you have any access to the vessel ahead of the inspection?

What the cold does affect is our battery capacity, or at least deep cold (zero F or so). The compression release is to ease up on the cranking load of the limited batteries, to spin the engine the use inertia to get it few a few turns. I've use twice. Both times when for stupid reasons I had almost a completely dead battery(s) because main with was on BOTH and it was pretty chilly (35 degF) in Chicago. I knew I had one shot and was on a mooring. Worked both times...easy.

If the batteries are fresh and all charged up I would simply give it a try. I assume your fuel has stabilizer in it. Battery strength is the main concern. Even though they loose capacity with decreasing temperatures you can still charge them up to a better level and have good capacity.

Anyway start simple and see what happens (no pun intended :) )

Good luck.....here is chicago it's been a relative heat wave. We've been up close to 70 degrees! In February???
Best Regards
 
Feb 7, 2017
3
Sabre 425 Rhode River, MD
I really like the space heater idea and giving lots of time.
Will buyer want to check fresh water systems? Consider filling system then running shore power water heater to heat engine 'coolant'. Again, time needs to be on your side.
Rick
 
Sep 15, 2013
661
Catalina 270 Baltimore
+1 on the space heater. You will subject your engine to greatly increased wear by starting it cold. If the surveyor complains tell him you will not (and have never) subjected your engine to that type of abuse.
 
Apr 7, 2014
8
Hunter 30 Nyack, NY
The Yanmar 2GMs that are used with Thermo King coolers on tractor trailer rigs have a Glow Plug that resides in the intake manifold. That way they start at any low temperature. Heats the intake air just enough.

Boats in the North East are out of the water 6 months of the year. If they were in the water for the winter the water only gets to the low 40s, Generally. Hair dryer works on a stubborn engine.