# Diesel Engine won't start



## NCShadowdragn (Feb 9, 2009)

Have a 1985 Hunter sailboat with a 3 cyl. Yanmar diesel engine that was rebuilt just over a year ago. No glow plugs. Ever since rebuilding, the engine has been hard to start especially in the cold weather. Been having to flip two of the three compression switches to help start but now that isn't even working. Some white smoke coming from exhaust while trying to start. Any suggestions or possibilities of what the problem is?


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## djodenda (Mar 4, 2006)

Welcome to Sailnet!

We can be a bit more helpful if you answer a couple of questions:

1) What kind and model of engine is it?
2) Does it have a glow plugs?
3) Does the engine crank as fast as it did when it used to start?
4) Have you done anything to the engine recently?


David


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## peikenberry (Apr 26, 2000)

If a diesel won't start it generally is due to one or all of three things
fuel not getting to the cylinders
air not getting to the cylinders
not enough compression

smoke usually means unburned fuel, but not white smoke. White smoke usually means water in the cylinders. This could be a head gasket leak. 

First check cranking speed. Is the battery charged and strong enough to crank the engine fast enough. Otherwise you are not getting enough compression for it to fire.

If cranking speed is up and compression ok check your air and fuel filters to make sure they aren't clogged.

Check to see if you have water in the fuel. Water makes diesel fuel look milky.

If you have glow plugs make sure they are working. Cold weather always causes hard starts but glow plugs help.

If you still have the problem then you need to have a diesel tech run some tests.


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## jrd22 (Nov 14, 2000)

I'm guessing you have a Yanmar 3gm, but they are all similar. White smoke while cranking can be unburnt fuel, ours did that and we had the injectors rebuilt (and then replaced). That helped the hard starting and reduced the white smoke. Another thing that we have used recently that seems to help is something I read here on Sailnet. Pull your stop cable out and crank for 10 seconds and then push the cable in while cranking, usually fires right up. Hope that helps.


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## timebandit (Sep 18, 2002)

???NO FUEL IN THE TANK???

Trouble shooting requires questions and answers.



NCShadowdragn said:


> Have a 1985 Hunter sailboat with a 3 cyl. Yanmar diesel engine that was rebuilt just over a year ago. No glow plugs. Ever since rebuilding, the engine has been hard to start especially in the cold weather. Been having to flip two of the three compression switches to help start but now that isn't even working. Some white smoke coming from exhaust while trying to start. Any suggestions or possibilities of what the problem is?


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## SteveInMD (May 11, 2007)

No fuel in the tank is a good guess. An air leak in fuel system is another.


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## badsanta (Oct 16, 2006)

I have to do this on mine when cold. Make sure battery is full. I turn off the water intake. Open all the decompression levers, crank for 5-10 sec to get the oil moving. open to 3/4 full throttle, crank for 5 sec. close decompression levers and start, reduce throttle to idle and open water valve. I think that the increased oil pressure and the fuel increases pressure. The white smoke is probably just unburnt fuel. But you don't want to just keep cranking the water through the engine


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## Joesaila (May 19, 2007)

*Battery?*

Where you just had it rebuilt I would suspect the battery is too low. If you live in a cold climate the sugestion re closing the seawater cooler is right on. That suggestion re opening the decompression levers is worth trying too. Let us know what works.


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## hertfordnc (Sep 10, 2007)

Someone mentioned the battery- Specifically, the battery and wiring

look closely at the wiring from the battery to the power side of the starter (that's the big terminal) Also check where the negative cable connects to the engine (ground). 

Check every connection. Look for corrosion on the terminals. Peel back the insulation and check for corrosion (green) 

Your electrical system can work fine in all other respects but if there is corrosion on those big wires it creates resistance which turns current to heat. 

That will cause your starter to turn slower and fail to start the engine. 

Electrical problems cause confusion. A good battery and wires will allow the engine to spin fast enough to start and that may overcome worn valves or injectors. Likewise, fixing bad valves or injectors may allow the engine to start easier despite a week electrical system.

But wires are cheap and no skill is required and it's pretty hard to make it worse so it's the best place to start.


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## NCShadowdragn (Feb 9, 2009)

Plenty of fuel in the tank. Thanks for all the suggestions. We plan to head for a dock under sail tomorrow and get fully re-charged and try again. Will let you know how it goes. Again, thanks for all the suggestions.


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## Leither (Sep 30, 2008)

I guess you have had the full range of advice to work on and I won't add to that, except to say that I agree completely that your first step should be to make sure the battery is fully charged.

On a more general note, it is interesting to see how many people have starting "difficulties". The single-pot Volvo diesel in the boat I owned in the UK was always a slow starter, especially following de-winterisation. It had been fully checked out and everything was OK, except that the compression was slightly lower than new (not surprising, since it was 20+ years old), although within an acceptable range. The Yanmar 2GM in my present boat starts effortlessly, even in cold weather. It has low hours and I am simply speculating that older engines are slower to start mainly because of the declining compression issue.

Of course, engines with glow plugs will be different, since presumably the plugs would be able to "compensate" for the declining compression..... 

Anyway, good luck and happy starting!

Stuart


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## seajayy (Oct 31, 2016)

Are Yanmar engines good reliable engines to repower a boat. I recently purchased a boat with a YANMAR 4JH-HTE 4 cylinder engine that will not crank over. I am looking for ideas where to start trouble shooting this. The engine supposedly has 375 hours on it. Should I be worried.


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## arf145 (Jul 25, 2007)

It probably would be a good idea to start your own thread on this, seajayy, instead of attaching to a 7-year-old one. Include as many details as possible. Like, when you say won't crank over, do you mean no noise when you hit the start button? Or that it cranks, but doesn't fire.

Oh, and Yanmars are good engines.


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## kd3pc (Oct 19, 2006)

seajayy said:


> Are Yanmar engines good reliable engines to repower a boat. I recently purchased a boat with a YANMAR 4JH-HTE 4 cylinder engine that will not crank over. I am looking for ideas where to start trouble shooting this. The engine supposedly has 375 hours on it. Should I be worried.


Crank or not crank??

4J Yanmar is likely one of the most reliable modern small diesels out there.

Battery state would be the first place to look, oil level (some have oil temp/level sensors) and neutral position sensors (so it doesn't start in gear). It may have a mechanical stop lever/cable if it is an older boat that shuts fuel off to stop the engine....these are not like automotive diesels where you just turn the key off.

more info would help


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## capta (Jun 27, 2011)

I would not be cranking it with one cylinder on compression. Normally, one opens all compression releases and gets the engine turning over nicely then drop one compression release then the other(s) in the firing order.
What this does is circulate oil, water and fuel in their systems without the resistance of compression and stress on the starter. If you use starter fluid (as directed on the can and not too often) your diesel should start when it must (emergencies), but it won't help until you have compression.
Once it is running, how does it run? Does it hunt at idle, a sure sign of air in the fuel system. Have you changed the fuel filter since the rebuild and before the problem with starting began? Did the weather get colder just before the problem began? Do you have glow plugs that are not hooked up or can you add them? This also might help.
At any rate, with no compression, once you get the engine spinning nicely it should start on one cylinder without problem. If it doesn't and won't with starting fluid, then perhaps compression is the problem.
As for electric, with no compression, you are not putting much load on your battery so I doubt that electric is the problem. However, when it is, or at least a contributing factor, then most often it's the ground wire to the engine which is causing the problem. Clean that connection just for jollies anyway; it probably needs it.


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