diesel knowledge needed

[fishingaz]

hi all. am after some advise on the starting of my nanni diesel
its a 85 hp in a small fishing boat.when i havent been on the boat for a couple of weeks.i just turn key to warm the glow plugs for about 30 seconds then just hit the starter and it fires up in a split second which is very pleasing.all great there but.when i go offshore and run for an hour or so at around 2600 revs still runs great.then i pull up and stop engine then after 20 mins or so try to start .and it will wind over a good 5 seconds before it fires.
has anyone any ideas?
thanks in advance.
gaz.

[svBeBe]

Wild-ass guess:
I wonder if you are getting more compression when you cold-start it? It may start slower with lower compression and if it is worn, you may lose compression when it warms up.

You might get the compression checked when it is warm.

Bill

[Sunspot Baby]

Sounds like the injectors need service. When cold starting the glow plugs could be igniting the fuel.

[mrm]

How many hours on the engine?
When this happens again, pour/spray cold water over injection pump high pressure side to cool it down and see if it helped.

[fishingaz]

thanks for all the replies.food for thought.
the engine is 85 hp 250tdi 2002 model with 600 hours on it.

[In Deep]

It shouldn't be broken in good yet, must less worn enough to have low compression. Try using the glow plug when it's warm and see what happens. Also Marvel Mystery Oil will clean the injectors, etc. I think it'll tell you on the bottle how much to pour in per gal.

[Nemo55]

Could be a tiny leak in the injector distributor pump body,when it gets hot its fine but as it cools it causes a partial vacuum and draws air into the pump body or dist.