Engine won't start! How to troubleshoot your marine diesel electrics - Yachting Monthly
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- Опубліковано 26 вер 2024
- If you try to start your boat's inboard engine and it doesn't turn over, what do you do? Know what to check and where to start is the key to getting up and running, or getting the right help, as quickly as possible. Matt Sheahan talks to offshore yacht instructor Bruce Jacobs at Rubicon 3 (www.rubicon3.co.uk) for his five minute guide to troubleshooting your marine diesel electrics.
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This yellow starter wire is EXACTLY why my engine wouldn't start. Thank you so much!!!!
Check battery voltage while trying to start the engine. You might see the voltage drop significantly; a battery of that type is a "voltage source" as it will try to develop 12V DC across any load - even a dead short or very low resistance such as the winding of a starter motor. As such, with a weak battery trying to turn over a stubborn engine you might see the voltage drop to 4-6V which is a sure sign that the battery is in need of replacement.
You should expect to see the voltage drop 1V or so when starting, but consider anything under about 10.5V measured (with a quality meter such as Fluke) as a problem.
Also, you may need a very high end handheld voltage meter (or a very low-end oscilloscope) so you can check for other issues mentioned in this video. For example, simply measuring voltage at the alternator may not lead you to notice a damaged rectifier; a DC offset or leaking AC can damage some equipment.
If I had the meter in my hand and had checked the battery voltage, it would be an obvious move to look for exactly the same voltage at the starter solenoid's heavy positive cable since they're usually directly connected. If they're not at the same voltage, check connections and integrity of the cable. This is worth doing anyway, since a dodgy cable will give you a voltage reading even if it's down to it's last strand of wire. It will never carry the juice to turn the motor over though.
If all looks good, bridge the two large terminals on the solenoid with a screwdriver. If she fires up, the problem is on the control side (ie from battery positive to ignition key, to smaller positive wire on the solenoid). So you've narrowed the thing down pretty easily.
Sometimes a few judicious taps of a light hammer on the body of a starter motor will persuade it to spin. Don't overdo it.
A stop solenoid, if it has two terminals, can be checked just by putting voltage on the teminals. The plunger should pop in and out as you do.
watching this video solved the problem i had thanks very much.
Great video nice and clear. Better seeing an actual engine and having it explained. Txu for taking the time to make this video regards from New Zealand
When re-connecting a loose spade connector, surely you should crimp it otherwise it willl be a very temporary fix.
So you started the engine to check if the alternator was working. But you were doing this whole thing to diagnose an engine that isn't starting. Top notch video.
The video traced the electrical system to find why the engine wasn't starting. A failed alternator won't directly stop the engine starting, but it will stop the batteries charging. The only way to test if an alternator is working is with the engine running.
12 volts coming the the altinator won't charge the 12 volt battery, you need 14+ volts. I like the out of the boat set up though.
Thank you very much, very helpful!
Excellent presentation on electrical trouble shooting.
This was amazing!
If only it was so easy to access all the various component of the engine.
Thanks sir
great stuff thanks!!
Very helpful, clear and to the point 👌
I expect c.14V at the alternator when running...
Great info. Thank you.
If you have a glow plug system leaving it on with the beeping sound is a bad idea
12.8 charging system voltage is not good, you should have 13.8
i thought that to be so as well. Am i missing something?
At least 12V
I have a nanny diesel kubota 29hp just had new starter motor and two new batteries fitted always serviced and the relay done and it won’t fire over please someone help not even the boat yard can diognose anything
Thank you
Hello Im from Argentina , my engine turns but doesnt fire! My stop solenoid is broken, but why the engine is still turning? I think may be you will not be able yo STOP the engine once its started, but not keep you from starting ?
Anyway i just ordered a new solenoid as i was looking the video! But i still dont get it .. sorry!
😮I got all new batteries since previous drained. I don't even heard the sound for the start. Everything works but no the starting.
I am desperate for help and no one here does deasel.
Love this 👊🏻
4:35 Guvnah!
I know , Ship Medium Lumber Modern Engine MTU Or Engine CAT , Yanmar Ship Medium Little Ship Beach Wave 😊
Good video, need to explain in more detail what you are checking, what is a "stop solenoid". Do all
diesel engines have these? 12.8v is not good, should be above 14v. Yachting Monthly needs
to review these video's before publishing them.
A stop solenoid is a fuel shutoff solenoid. If it's energised and all is well, it allows diesel to pass through to combustion. It helps prevent backfiring, and flooding. To get it to energise, it might need to see certain conditions eg oil pressure.
Sorry, Checking the battery right off the start with a voltage meter is WRONG..... AMPS is the key , Even a dead battery reads 12.4 volts , Yes AMP testers cost money but worth every penny . Without AMPS you get no crank .
What is the likelihood that the contacts within the solenoid is dirty due to sparking creating resistance & voltage drop?
Checking voltage on a battery is not very helpful. You shoud check only under the load. Nearly dead battery can show you 12v but under small load such as light bulb can significantly drop.
is the alternator bad if it is reading 15.8v with the tester?
Not necessarily and actually not likely. An alternator's voltage output is directly related to the engine rpm. Increased revs leads to higher output voltage, and vice versa.
A nominal '12v' system wants an alternator that delivers a little more than that, maybe about 14v, which is enough to charge the battery but not enough to wreck it.
The component that does that is called the 'regulator,' and it's sometimes built into the alternator itself. It acts to divert anything over the desired voltage away from the battery. Sort of like a hole in the side of a bucket that only lets you fill the bucket to a predetermined level.
I stand to be corrected, but 15.8v is possibly on the high side for a 12v system.
Hi. How can I check the electrics before the starter motor eg the push button and the cable that goes to the starter motor (the loose white one in this video) to make sure they are working properly?
Thanks Andy
Question; I have a small 2 cylinder Yanmar in my sail boat. Each time I attempt to start the engine- the starter housing breaks. I have replaced 3 starters now. Its like it doesn't mesh correctly? Am I missing something?? The engine block where the starter is bolted seems clean and correct. Please help with any info?
Is your engine seized? causing starter to break.
Your alternator is broken, you should be reading from 13.8 volt to 14.7 volts
120k views and so little likes … is good advice not appreciated anymore?
Hi! watched this video ten times now. gone through my engine and changed/checked everything in the fuel system except the injectors, I do not know how to do this. I have an old Volvo penta MD6. when the compression handle is lifted the engine turns but as soon as I lower it there is no more action, no combustion of fuel at all. it took longer and longer last summer to start it up, untill one day it didnt start at all. any help from anyone is very appriciated!