Yanmar 1GM1o Start Problems

[cxmarshall]

I have a Yanmar 1GM10 approx 1996 with not many hours on it (approx 400)
Over the last 6 months it has become increasingly difficult to start.
I now start it by applying no throttle at all. The engine fires almost straight away but will not take revs. If I apply throttle it becomes sooty and sometimes stalls.
If I leave it to tick over on starting instead of applying throttle there is a slight change in engine tone after approx 30 secs. After this 30 sec delay it will take throttle and then I have no further problems.
The injector has been removed and serviced by LSUK two weeks ago. They said it did need an overhaul but that has had no impact upon my starting problem.
I removed the exhaust elbow and cleaned the carbon out but it was not excessive.
When the engine is warm is emits a small amount of bluish smoke but is not sooty at all.
The air filter appears to be clean.
Anyone got any suggestions ?



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[johnneale]

Have you looked at your tappets ?

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[ShipsWoofy]

This could be a coked up head. I had a car engine that behaved exactly like this. The time delay was described to me by a mechanic as the time it takes for the carbon to get red hot and then it appears to work better.

I removed the head of the engine cleaned it all away and re ground the valves, it worked perfectly after that.

This of course might be rubbish, but it just sounds to similar to dismiss. Thing is, I don't know how or if you can check for a coked up cylinder head without actually removing it. Though the 1GM head looks a doddle to remove.

Someone is going to say bore glazing soon /forums/images/icons/frown.gif

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[Marsupial]

The problem is the engine is only getting about 50 hours use per year, and I bet thats about 100 stop start processes, so just half an hour running per start, idling most of the time. It wants to be used.

I don’t know where you are in the world but I would be inclined to change the engine oil, check the tappet clearances, impeller and water inlet filters then take the boat on a 20 hour round trip at its "continuous maximum rev" all the way there and back. On the return trip you will notice a difference in the way the engine runs, furthermore at the risk of being very contentious in this forum I would also put a double dose of fuel set in the fuel, it will decoke the engine as it runs.



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[Appleyard]

A suggestion before you dismantle anything... GO to www.forteuk.co.uk and click on advanced formula motor flush.. follow the instructions ..ie warm up the engine,pour this into the oil,run at t/over for 20 mins,drain,change filters and refill.This will clean all the sh?t out of the c/case,deglaze the bores and clean varnish from the rings,free the valves and clean the engine internaly. Give it a try.. you should be able to get it from a commercial vehicle garage, or try online for a supplier it comes in 1/2 litre tins so is very economical and is worth trying first.After you have done this then put some fuel conditioner into the tank before the next run. We have been using this stuff for many years on lorry and plant engines and it works. I have no connection to the company.

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[Appleyard]

Forgot to say... THEN take it for a long hard run. Diesels like to be worked hard.

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[oldharry]

A long hard run at least 3/4 throttle, for 3 - 4 hours, and all will be well. If not, you have a fuel problem: possibly a minute leak which is allowing microscopic amounts of air into the fuel, which once the engine is running purges itself: check the filters are not blocked, and the lift pump functioning correctly. A pinhole leak in the pump diaphragm can cause all kinds of strange problems. Does the engine have any sort of cold start mechanism? If so, is this functioning correctly? The fact that it clears after 30 seconds could be the result of some sort of delay mechanism modifying the fuel delivery not working properly, though I do not know of one fitted to these engines.

If none of these, have the injector pump checked for a sticky governor.

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[nealeb]

I used to have a very similar problem with my 1GM, in a heavy-ish 16' baby gaffer. Engine seriously overpowered for the boat so never really thrashed. It always started easily, and would generally rev OK out of gear, but would take a while to get up to speed in gear when cold. In fact, the symptoms were very much like overpropping - failure to rev, lots of smoke and no go, etc. After a few seasons I decided that at least part of the reason was prop fouling which increased engine load considerably and whether or not there was also an engine problem the dirty prop did not help until it had run enough to get rid of the worst of the weed. Start of the season with clean prop was always much better. If you get a chance to clean the prop it may be worth a go to see if it makes a difference.

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[Gunfleet]

Are you sure the engine fuel filter is clean? I mean the one after the first pump, actually on the engine. I had a similar problem and found that was very finely blocked - so fine in fact it was difficult to see. The other symptom was it had the habit of sometimes conking out as I moved it between forward and reverse.

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[Cantata]

I would put money on a simple answer - a minute air leak, or blocked fuel filter. I also had one of these engines, it was brilliant and the one problem I had, sounding remarkably like the one described here, was caused by a minute air leak (which was in the fuel take-up pipe within the tank).

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