Yanmar 1gm 10 starting backwords!

[LiftyK]

Thanks for all replies! I am thinking it is starting backwards as it is only starting from cold when you stop the pressure on ignition key spring. As it loses turning momentum and almost comes to a halt, it seems to start and reeks smoke out of engine compartment. Sound rough as. Killing engine and then trying again it will spin up on key and if you keep going 10 seconds, it might fire reluctantly and then it is smoke free and running. Always spin it up with decomp to get oil up initially. The trick of spinning up and dropping decomp, only encourages the rough starting, as it starts at the end of flywheel rotation. It seems to bang against the compression as flywheel nears stop of rotation..........then rough as hell running and smoke.
Get it started and fine all day. I better check oil levels and see if they are raised with fuel dilution.
One thing I have realised now I may have been doing wrong, is I am not giving any throttle on start up. This is my second full season with this engine and all last year it started from neutral in tickover speed. Will try in 3/4 throttle along with the other things. Water impeller was first thing I feared for as I know how easy they get fins broken. I thought of oil pump gear too. The speed it is spinning at on the starter motor should start it I think..........sounds about same as last year.

More thought. What changed between last year and this year? If it worked last year, starting in idle position as mine has done for over twenty years. something must have changed. Do you have two batteries? if so, if you pair them to start the engine does this make any difference?

 

[lexi]

I had this happen during a spell when I had an alternator problem and mistakenly used an alternator with an overly heavy load due to incorrect pully size. Could your engine be experiencing unusually high load at start up?

If you mean high mechanical load, no. It spins like a Top with the decomp off. Standard Hitachi alt.

 

[lexi]

More thought. What changed between last year and this year? If it worked last year, starting in idle position as mine has done for over twenty years. something must have changed. Do you have two batteries? if so, if you pair them to start the engine does this make any difference?

Good question. Only difference from last year is,I have connected another battery along with original. It is just connected ie extended from original. Positive to positive and negative to negative. If a cell has gone in one it may pull the other down? I am up to boat tomorrow with a fresh battery.

 

[bignick]

I always start my 2gm20 on 3/4 to full throttle and reduce as soon as it fires.
Starts instantly on the button every time.

 

[lexi]

Down to boat at Loch Lomond yesterday. Multimeter played up so got no readings from battery's . The green indicator was on both though. Checked oil and level and colour was fine. Took air filter out and there was soot in casing. Filter was not bad as a new one this season. Definate signs of that smoke blow out though. All connections good. 3/4 throttle made no difference. She started very reluctantly on idle at the release of starter pressure........smoking and rough. Killed it. I did not have cover off so could not tell if alt pulley was going backwards. This is an open boat and it was pi$$ing it down. It started properly on next turn, forcing it with starter so to speak. Ran normally for 6hrs.
I found a battery for multimeter and at stop, both battery's read 13.4 volt. Started her up and both battery's at 14.4 volt. Next plan is to check battery from cold and on a dry midge free day get cover off, and ascertain that crank is going backward.......I am sure it is. Will keep you posted and thanks to every one of you for the interest.

 

[penberth3]

Down to boat at Loch Lomond yesterday. Multimeter played up so got no readings from battery's . The green indicator was on both though. Checked oil and level and colour was fine. Took air filter out and there was soot in casing. Filter was not bad as a new one this season. Definate signs of that smoke blow out though. All connections good. 3/4 throttle made no difference. She started very reluctantly on idle at the release of starter pressure........smoking and rough. Killed it. I did not have cover off so could not tell if alt pulley was going backwards. This is an open boat and it was pi$$ing it down. It started properly on next turn, forcing it with starter so to speak. Ran normally for 6hrs.
I found a battery for multimeter and at stop, both battery's read 13.4 volt. Started her up and both battery's at 14.4 volt. Next plan is to check battery from cold and on a dry midge free day get cover off, and ascertain that crank is going backward.......I am sure it is. Will keep you posted and thanks to every one of you for the interest.

It's well-known that engines can and do run backwards, some do it more readily than others. Has anyone mentioned checking the injector timing? If that's not correct it could be helping the reverse starting.

 

[Tranona]

It's well-known that engines can and do run backwards, some do it more readily than others. Has anyone mentioned checking the injector timing? If that's not correct it could be helping the reverse starting.

Difficult for the injector timing to be out on a 1GM as it is essentially fixed at the factory through the use of shims between the pump and the front timing case. The workshop manual does give instructions for setting the timing should the pump and case be dismantled and shims damaged or disturbed. When I did it The shims were damaged and I replaced them with exactly the same and timing was spot on.

 

[lexi]

Runs like a sweetie all day long. When it starts proper it is smooth running from the off.
Low battery, lazy starter, air/bleed or injector are chief suspects I think.

 

[dukeofted]

It sounds more and more like my 1GM10. It is definitely worth getting the injector checked, if only to eliminate it as a possibility. Any diesel injector place can check a mechanical injector for cheap or free. If it comes back good then at least you know. Mine had a terrible spray pattern and I got it rebuilt for about £160. Engine was absolutely spot on after that and started perfectly, even when we had ice in the bilge. Pre injector servicing it would take a long time to start, catch and run. It seemed to start easier in reverse when it would bounce back off of the compression. Once started it always run perfectly for as long as we needed and never caused any problem at all.

 

[lexi]

Latest on this is that Injector has been checked by Argyll Diesel and found to be bang on pop pressure and spray pattern. I ran engine yesterday after one false backward start. When started it ran 6hrs. Took injector out on a hot engine and got it tested this morning. I noticed a very occasional drip when running, from the injector end of the hard pipe. Tightening to max it has a light drip every few minutes. Pipe flare must be worn. I have ordered a new one. This is a possible as injector man said it may be losing a tiny bit of pressure for fuel on cold start. This same pipe leaked a bit last year but responded to tightening. Flare end may have worn a bit more this year. Let's see.

 

[Topcat47]

Older 1GM10's can be buggers to start. I know, Mine's one of them. A fit battery and a good starter motor are essentials. My method from cold is, spin the engine up with the decompressor on and full throttle. then drop the decompressor and only when the engine is firing regularly, stop the starter motor and reduce the throttle.

+1 on the oversized alternator, too. There's a reason they use the tiny Hitachi Alternator.

 

[lexi]

Just to update this. New fuel pipe and the tested good injector fitted. Bled up and no change. As soon as it tries it backward attempt to start, I lifted de comp lever to cut it out. After one or two attempts of this, it finally starts. On getting underway, I notice fuel dripping from the new pipe union thread at injector. I now have to tighten to max to stop drip. I have no more to tighten should it drip again, so am back at square one, as this is why I replaced this Injector Pump to Injector pipe.
Fact is that I had an occasional drip from it last year and it did cold start fine. Next is to make sure cranking is up to speed ( seems fine?) I may have to put up with this until boat is back home and I can strip bits out for testing. The engine runs all day, and so far I have not failed to actually start it at beginning of day. Compression chamber may need checking or Injector pump for wear etc etc. All winter jobs.

 

[lexi]

So first winter job now that I have Vagabond home. Thought I would check the exhaust elbow. Looked Ok and put the boiling water down the chamber.. I found a split pea sized hole in upper half of the inner exhaust pipe. Wonder if that is the problem. Ordered a stainless one. Lets see.

 

[dukeofted]

That could cause a problem with water getting into the exhaust valve causing it to rust. You would lose compression in that case, which would make starting harder. But it wouldn't bounce off of the compression and run backwards if the compression was low.

 

[lexi]

That could cause a problem with water getting into the exhaust valve causing it to rust. You would lose compression in that case, which would make starting harder. But it wouldn't bounce off of the compression and run backwards if the compression was low.

That is what I thought. Get the new elbow and check timing next. I take it the starter comes off to view the marks?

 

[Tranona]

That is what I thought. Get the new elbow and check timing next. I take it the starter comes off to view the marks?

Se post#27. you can't change the timing unless the pump has been removed and the shims changed. It is set at the factory.

 

[Refueler]

Why would that be? he is not shutting off the water.

probably because it forces the Impellor blades to bend back and curve other way .... they ewould need to fold significantly to do so. Just thinking.

 

[lexi]

Se post#27. you can't change the timing unless the pump has been removed and the shims changed. It is set at the factory.

Yes. Have heard that shims can be damaged/worn though. A previous thread says that when elbow is leaking, the engine can take a gulp of water on shut off. That itself could be issue here. Will try starting here with new elbow anyway.

 

[Bilgediver]

The answer is simple. use the Heater Plug, every time.
Regards.

Can't find it. please advise where it is ?

 

[Refueler]

Pal of mine has 1GM ... he had poor starting and quite often it would 'rebound' and fire ... when it ran - it was 'lumpy' - but as far as I know it didn't run backwards.

He is a 'tinkerer' and decided to have a go at it ... he found that the strange little pump gadget was only really working partly ... it seems to be a particular design only on Yanmar .... he tried getting it to pump ... but failed.
I posted about this part on here quite a while back ....

Anyone have an injection pump - YSE12

In the end after he'd dismantled the engine ... and then had no solution - he found a second hand engine for LESS than the cost of a new pump !!

Fitted it and he's now very happy.

Just commenting.