Starting problem

[mick]

I have a Bukh 10HP diesel which I am having trouble starting. When I turn the key there is a dull thud as the starter tries to spin the flywheel. After a few seconds delay the starter spins but rattles. Eventually the engine fires, after several attempts. This with a brand new battery. Any comments appreciated.

 

[kgi]

I suspect your head gasket is going,is it raw water cooled? Ihad a similar problem, and it was the gasket, when you shut the engine down a dribble of water comes in from one of the coolant passages, this causes the thud and then the engine finally expells the water and it starts to turn...........i maybe wrong but thats what happened to me.....keith

 

[Avocet]

Sounds like the starter motor is dead. Did you change the battery because of this problem? IF so, and it's still there, the starter motor would be the next guess. If you didn't, maybe there's a high resistance on one of the big cables feeding the starter.

 

[Johnjo]

Almost certainly head gasket, Had same problem on a Volvo twin.
You are trying to compress water.
Serious damage can and probably will happen if you persist
in trying to start,check it out before you go any further,
all the best,
mike

 

[mick]

Mike,
Once started the engine runs perfectly. Am I still likely to cause damage if your diagnosis is correct?
Mick

 

[SloopJohnB]

If it were me, I'd trace electrics and then starter motor. You should be able to isolate problem yourself.
Good luck
John

 

[vyv_cox]

Before starting with the starter motor turn the engine over by hand. If there is water in the cylinder you will certainly detect it like this. I once had the same problem with a road vehicle. We used to push it forward in gear until the piston went over dead centre and it would then start perfectly. Ultimately the engine blew up, though, 500 miles from home with an 18ft catamaran on a trailer behind! An expensive tow home resulted. So fix it soon.

 

[extravert]

I had both problems suggested here with my Bukh 10.

Firstly it was very sluggish starting even with new batteries. I sorted that one by replacing all the high current cable, connectors and battery isolators. I cleaned and changed the connectors where the cables joined the engine/solenoid as well. What a difference that made! That was £20 well spent.

Then later my head gasket went. I had water coming out of my air intake when turned by hand. Water had got onto the cylinder head metal and corroded it too deeply for skimming. The cost of a new head added to the cost of a new saildrive leg which was also on its last legs was the end of the engine. If you suspect you may have head gasket problems, get the head off sooner rather than later, because the cost of spares kills Bukh engines before their time.

If you (or anyone else) do need some Bukh 10 spares then I have a pile of them in my garage which I am selling for 25% of the new price, but quite a few have gone already and probably the bits you may need, ie head and starting system.

 

[castaway]

I had a similar prob on my last boat with my Sabb 10hp, it turned out to be the battery isolator switch. I would start by checking for any high resistance areas in the cabling.

Nick

 

[Johnjo]

Can you turn it over by hand?
If so , Do'es symptems you discribe persist?
Do you have good compression?
If it is the head gasket,It will let you down completly .
When mine went,Oil level in sump rose slightly.due to water passing the piston.
Is oil the right colour, Is it going grey? Should be black.
With mine, Iwas getting unburnt fuel floating on sea from exhaust.
Do you have more steam than normal coming from exhaust?
As the other poster said. Check all your electric's ,
Easier to check them, removing head is LAST resort.
hope this helps,

mike

 

[brianrunyard]

I suspect you've got a high resistance somewhere in the supply.
Check for volt drop between battery positive terminal and stater, when starter is engaged.
If you have a volt drop:
1. Repeat between battery terminal and each point between there and starter.
If no volt drop in positive, check between battery negative and starter ground.


Brian
http://homepage.ntlworld.com/brunyard