glow plugs

[fishy]

Can anyone help a newcomer? We bought our first boat six monthes ago and it has a ten year old Beta diesel. It's been starting perfectly first time everytime. Including when the weather was really cold. But this weekend it totally refused to start.The battery is fine. The air intake is clear.I bled the fuel system and just diesel, no bubbles appeared.A mechanic who checked the engine when we bought it said he thought the engine and compression were fine.
The only thing I can think is that the glow plugs have ceased working. This may be my fault.I was under the impression that with marine diesels you had to give them 20 seconds or more before starting. But I now know that this is incorrect. Is it possible that overheating them regularly has ruined them? If so is it straightforward to change them. I would really appreciate advice as we're planning to do our first channel crossing next weekend and the boat is completely out of action!

 

[castaway]

Generaly easy to get them out and check. Just pull them out and make a circuit ,, they should glow bright red within a few seconds. I usually give mine 10-15 seconds but at this time of year an engine with decent compression should really be starting Ok even with out the glow plugs.

Regards Nick

 

[LadyInBed]

It's straitforward to change them if you can get a 'long reach' socket to them without having to move pipes and other mechanical gubins first.
Before you go that far, get a multimeter, (if you haven't got one, it's a handy bit of kit to have onboard anyway) disconnect the wire at the top of each plug and measure the resistance between the top of each plug and the block. The resistance should be in the order of about 50 to 200 ohms. If you get an open circuit reading the plug is U/S. If you get a high resistance reading say >400 ohms the plug will not be getting very warm and it is 'nearly' U/S!!

 

[Whiskey2]

Hi,
we have owned our first boat for 6 months as well, it has a new volvo 2020 fitted it had a faulty ignition switch which meant that the heater plugs did not work but it still started eventually. We had the engine repaired under warranty and it was the relay and switch that were at fault the plugs were ok.
We have yet to persuade our insurance company that we are compentant enough to cross the Channel!! Mel

 

[dickh]

Yes, sounds like the the heater plugs or the relay. Usually heater plugs are quite reliable and shouldn't suffer from overheating. Follow the suggestions above and you should cure the problem. I always carry a spare heater plug in my onboard spares kit but have never used it yet. The only problem I have had is when in Holland the engine wouldn't start one morning and I convinced myself the relay had gone, then noticed that the wire to the heater plug rail had vibrated loose - the local chandlery made a temporary connection with doubled up wire(as he did not have the correct size) and got me going - in fact the 'temporary' repair was so good that it is now permanent. I always carry my electrical spares/toolkit on board now.

 

[oldharry]

Does yur engine have a stop solenoid? If so this is more likely to be the cause of the trouble as they have to be 'on' to allow the engine to run - any fault means everything comes to a dead stop! If the engine stop works from the starter key, then almost certainly thats the problem. Look for a pair of wires going to the Injector pump, either to a solenoid working a small lever, or to electrical contacts in the pump body. Lever action can be observed as the key switch is operated, and internally mounted units can be heard clicking open and shut. Either way its a simple enough job to diagnose and replace them.

If a good starter suddenly goes completely dead as you say yours has, its more likely to be the stop circuit than the pre-heaters, as the engine should be at least trying to fire at this time of year if the pre-heaters are down. Its unlikely you have damaged them by over-use as you describe - some engines the heaters remain on for a minute or more after the engine has cold started to ensure efficient running - even though the warning light has switched off. Normally they only burn out in use if the charging circuit is giving an overvoltage.

Provided the heaters are accessible they are no more difficult to change than the spark plugs in your car. For more info about their condition get a look at a Haynes manual for a diesel car - they have a photographs of the appearance of glow plugs in various fault conditions, explaining the causes.

 

[chas]

A slight warning!

Last winter I replaced the glo plugs in my engine. The old ones came out intact with a little difficulty. One of the new ones was obviously slightly oversize and broke when inserted and screwed in. As to drill the broken bit out in situ would have, almost inevitably, resulted in swarf in the cylinder head, I had to take the head off to clear the hole.
Incedentally, my manual recommends 30 secs of glo plug operation before starting. I normally get away with 15 - 20 secs.

 

[boatone]

Do you have a manual 'stop' cable pull? Is it pushed right back in? If its not pushed right back in the engine wont start.
I felt a right twit when I had this problem but that was all it was!

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