Yanmar 20 won' start when cold - exhaust back fill

[viva]

For how long can one run the starter motor with the engine not firing and avoid cooling water back-flowing into the cylinder via the exhaust valve?
Thanks

 

[Contest1]

Not sure but you can start with the water intake closed!

 

[Ardenfour]

+1

 

[Tranona]

For how long can one run the starter motor with the engine not firing and avoid cooling water back-flowing into the cylinder via the exhaust valve?
Thanks

Depends on how big your water trap is and the length of the run from the exhaust outlet to the trap. However, as suggested avoid the possibility by starting with the intake closed, remembering to open as soon as the engine runs.

 

[NickRobinson]

Don't cook the starter- Is this a new fault or a regular starting sequence?

 

[lw395]

Obviously depends on the capacity of the exhaust.
In general, it takes a long time, longer than an engine should take to start.
Longer than you should be abusing the starter motor for.
And the engine is pumping air through the exhaust to some extent.
It is a risk if you crank the motor for a long time decompressed to bleed the injectors etc.

But if you are having problems, turn off the seacock until it fires, after a few seconds cranking.

 

[viva]

New fault

Don't cook the starter- Is this a new fault or a regular starting sequence?

It's a new problem. Having just launched after winter lay-up, cold starting is an issue. Always started on the button previously. Title should have read yanmar 2Gm20. I might try a hair drier in the air intake.

 

[lw395]

If it's cranking at all slowly, try a different battery.
Or decompress it and let it spin for a few seconds. Drop the decompressor and it should start.
It's not exactly arctic cold around here, there should be no need for hairdryers etc.
Next move would be to slacken the feed to one injector a little and check ejects a little diesel when cranked.

If you have mains, charge the battery.

 

[Tranona]

It's a new problem. Having just launched after winter lay-up, cold starting is an issue. Always started on the button previously. Title should have read yanmar 2Gm20. I might try a hair drier in the air intake.

Should not need a hair dryer this time of year - if at all. Usual problems are slow cranking because of poor connections or low battery, or not using enough throttle to start. As suggested, if it has a decompressor, turn over with this on then drop it when the engine is spinning and it should start.

 

[NickRobinson]

As it is an engine you are familiar with (ie not 'new to you') I'm sure you'll be working through it methodically, plenty of amps providing good cranking speed, no warm/hot terminals, air free fuel all the way to the injectors, no heater plugs on the Yanmar, but something to check on others, cold start procedures eg full throttle initiated and throttle cable doing its job at the engine end, plenty of compression, you can hear the compressions as you crank, stop lever or electricals not stuck on 'stop' etc....

Then its fresh charge time and some ether....?