Yanmar 2qm20 not starting troubleshooting

[thesauvage]

Hi,

I'm new to the Forum and I can't get my yanmar 2QM20 (year 1982) engine to start. I'm hoping to get some input of how to troubleshoot the issues that are preventing the engine from starting up.
The engine has been sitting unused /serviced for about 4 years. The amount of oil in engine & gearbox is good.

What I have already done/checked:

- Battery has enough power, Check.

- No water in the fuel/water seperator

- I unscrewed the HP fuel line to the Injector valves, and the fuel is squirting out if the engine is turning. So I guess the system is purged from air.

- When I try to start the engine (panel start button) it is turning/cranking but NOT starting/firing.

- While cranking the engine blows a little white smoke and some water through the exhaust.

I've tried to take a look at the injector itself, but it seems pretty stuck in the engine, and before ordering a removal tool, I'd like to know which other steps I could take beforehand, to find the issue why it's not starting.

Appreciate any advice / help.
Greetings from the locked down Med Sea.

Best Ric

[jimbunyard]

If it's "blowing a little white smoke" (and it's actually smoke -- unburned diesel) seems starting may be imminent.

Check that you have sufficient starting speed, this is critical. Remove and clean all connections from the battery to the starter, especially the primary cables. Check the cables for excessive or non-linear stiffness, which would indicate internal corrosion. Wouldn't hurt, if you have access, to loosen and retighten the starter mounting bolts.

Also, fresh fuel is a plus...

[Wotname]

Welcome aboard CF, Ric. Sorry to hear of the starting troubles as a first post but happy to hear you have a 2QM20 - it (and the 3QM30) my are favourite engines

You could have several problems or more likely, a combination of some issues. The white smoke is indicative that the engine is trying to start IMO.

The engine only needs three things to start; fuel, compression and air. The air is unlikely to be a problem in your case so lets look at the other two.

In no particular order.

1. The 4 year old diesel is somewhat stale. Normally not a problem but if compression is down a bit, it might be enough to prevent a start.

2. You might have introduced some air when you cracked the HP line at the injector but probably not. Trying bleeding the HP line again (youtube will have some techniques to get it right).

3. Marginal compression. Two things come to mind. First the rings maybe partially stuck in the piston lands after sitting for 4 years. Second, the battery might not be spinning the engine fast enough thus lowering the compression just enough to prevent a start.

Some things to try.

Use the decompression levers to decompress the engine and spin it over with the starter motor. After a few seconds, re-engage the decompression lever on one cylinder. If it fires, drop the other lever and the engine should run! This method will get the starting rpm higher than normal thus increasing compression.

If the ambient temperature is low, blow some hot air into the air take while trying to start. This adds some heat which may allow a start if the engine is already close to starting.

Get some lubrication into the cylinders to loosen up the rings and help provide a seal; both of which will help raise the compression. Normally you would pull an injector but more than likely, it will be difficult to get the injectors out given the age of the engine and probable lack of maintenance for some years. So a poor way is to remove the air cleaner, operate the decompression levers, spin the engine over while spraying something like WD40 into the air intake. Then let it sit for a day or so and repeat. Finally spin it over for a 5 or seconds (decompressed) without any spray. This is to purge any remaining liquid WD40. Now try a start.

Double check the electrical connections in the starting circuit, corrosion might be present after 4 years. Remove the connections, clean and refit.

Finally check the exhaust mixing elbow for any constriction.

Do remember to keep the seacock turned off while carrying out any of the above.

Hopefully the above will get you started!

EDIT: I see JimB is more succinct

[thesauvage]

Originally Posted by jimbunyard

If it's "blowing a little white smoke" (and it's actually smoke -- unburned diesel) seems starting may be imminent.

Check that you have sufficient starting speed, this is critical. Remove and clean all connections from the battery to the starter, especially the primary cables. Check the cables for excessive or non-linear stiffness, which would indicate internal corrosion. Wouldn't hurt, if you have access, to loosen and retighten the starter mounting bolts.

Also, fresh fuel is a plus...

Thank you for your reply!

I'have cleaned & checked all cable ends and connections from the batteries up to the starter motor.

Would it help if I upload a video of the engine cranking? Maybe?

[thesauvage]

Originally Posted by Wotname

Welcome aboard CF, Ric. Sorry to hear of the starting troubles as a first post but happy to hear you have a 2QM20 - it (and the 3QM30) my are favourite engines

You could have several problems or more likely, a combination of some issues. The white smoke is indicative that the engine is trying to start IMO.

The engine only needs three things to start; fuel, compression and air. The air is unlikely to be a problem in your case so lets look at the other two.

In no particular order.

1. The 4 year old diesel is somewhat stale. Normally not a problem but if compression is down a bit, it might be enough to prevent a start.

2. You might have introduced some air when you cracked the HP line at the injector but probably not. Trying bleeding the HP line again (youtube will have some techniques to get it right).

3. Marginal compression. Two things come to mind. First the rings maybe partially stuck in the piston lands after sitting for 4 years. Second, the battery might not be spinning the engine fast enough thus lowering the compression just enough to prevent a start.

Some things to try.

Use the decompression levers to decompress the engine and spin it over with the starter motor. After a few seconds, re-engage the decompression lever on one cylinder. If it fires, drop the other lever and the engine should run! This method will get the starting rpm higher than normal thus increasing compression.

If the ambient temperature is low, blow some hot air into the air take while trying to start. This adds some heat which may allow a start if the engine is already close to starting.

Get some lubrication into the cylinders to loosen up the rings and help provide a seal; both of which will help raise the compression. Normally you would pull an injector but more than likely, it will be difficult to get the injectors out given the age of the engine and probable lack of maintenance for some years. So a poor way is to remove the air cleaner, operate the decompression levers, spin the engine over while spraying something like WD40 into the air intake. Then let it sit for a day or so and repeat. Finally spin it over for a 5 or seconds (decompressed) without any spray. This is to purge any remaining liquid WD40. Now try a start.

Double check the electrical connections in the starting circuit, corrosion might be present after 4 years. Remove the connections, clean and refit.

Finally check the exhaust mixing elbow for any constriction.

Do remember to keep the seacock turned off while carrying out any of the above.

Hopefully the above will get you started!

EDIT: I see JimB is more succinct

Thank you very much for the warm welcome! Glad to hear that you like the 2QM20's :-)

- I have no Idea how 'old' the diesel fuel is, should I exchange it just to make sure it isn't the cause of my issues? Is there a way to determine if the fuel is still usable?

- OK I will re-bleed the fuel line, just to make sure.

- Decompression leavers on my engine are attached to each other via a bridge, should I separate them, to be able to decompress each cylinder separately?

- I've bought some 'engine starter spray' and took my WD-40 from my workshop But unsure about the amount to spray into the air intake.

I have uploaded a video of the engine cranking here:

https://youtu.be/yoh78Hugh2g

and here are some photos of the engine bay too:

https://imgur.com/AnJpYak
https://imgur.com/mnECqke

Thank you

[thesauvage]

Originally Posted by Wotname

Welcome aboard CF, Ric. Sorry to hear of the starting troubles as a first post but happy to hear you have a 2QM20 - it (and the 3QM30) my are favourite engines

You could have several problems or more likely, a combination of some issues. The white smoke is indicative that the engine is trying to start IMO.

The engine only needs three things to start; fuel, compression and air. The air is unlikely to be a problem in your case so lets look at the other two.

In no particular order.

1. The 4 year old diesel is somewhat stale. Normally not a problem but if compression is down a bit, it might be enough to prevent a start.

2. You might have introduced some air when you cracked the HP line at the injector but probably not. Trying bleeding the HP line again (youtube will have some techniques to get it right).

3. Marginal compression. Two things come to mind. First the rings maybe partially stuck in the piston lands after sitting for 4 years. Second, the battery might not be spinning the engine fast enough thus lowering the compression just enough to prevent a start.

Some things to try.

Use the decompression levers to decompress the engine and spin it over with the starter motor. After a few seconds, re-engage the decompression lever on one cylinder. If it fires, drop the other lever and the engine should run! This method will get the starting rpm higher than normal thus increasing compression.

If the ambient temperature is low, blow some hot air into the air take while trying to start. This adds some heat which may allow a start if the engine is already close to starting.

Get some lubrication into the cylinders to loosen up the rings and help provide a seal; both of which will help raise the compression. Normally you would pull an injector but more than likely, it will be difficult to get the injectors out given the age of the engine and probable lack of maintenance for some years. So a poor way is to remove the air cleaner, operate the decompression levers, spin the engine over while spraying something like WD40 into the air intake. Then let it sit for a day or so and repeat. Finally spin it over for a 5 or seconds (decompressed) without any spray. This is to purge any remaining liquid WD40. Now try a start.

Double check the electrical connections in the starting circuit, corrosion might be present after 4 years. Remove the connections, clean and refit.

Finally check the exhaust mixing elbow for any constriction.

Do remember to keep the seacock turned off while carrying out any of the above.

Hopefully the above will get you started!

EDIT: I see JimB is more succinct

Hey, thank you very much for your reply.
Glad to see that there are more owners of this engine type active here!

- OK, I'll re-bleed the fuel lines, just to make sure.

- Is there a way to tell if diesel fuel is still usable? Or would you advice to exchange the whole fuel?

- I'll give it a try tomorrow with the decompression levers, but my levers are both attached to each other via a bridge. Should I detach them to operate each of them individually?

- I've bought some starter fluid and I have WD-40 in my workshop, too. What would be the appropriate amount to spray into the air intake?

I took some photos and a video of the engine cranking, maybe it helps :-)

VIDEO: https://youtu.be/yoh78Hugh2g

Photo1: https://imgur.com/mnECqke
Photo2: https://imgur.com/AnJpYak

Thank you for your input and Help

[Wotname]

Originally Posted by thesauvage

Thank you very much for the warm welcome! Glad to hear that you like the 2QM20's :-)

- I have no Idea how 'old' the diesel fuel is, should I exchange it just to make sure it isn't the cause of my issues? Is there a way to determine if the fuel is still usable?

- OK I will re-bleed the fuel line, just to make sure.

- Decompression leavers on my engine are attached to each other via a bridge, should I separate them, to be able to decompress each cylinder separately?

- I've bought some 'engine starter spray' and took my WD-40 from my workshop But unsure about the amount to spray into the air intake.

I have uploaded a video of the engine cranking here:

https://youtu.be/yoh78Hugh2g

and here are some photos of the engine bay too:

https://imgur.com/AnJpYak
https://imgur.com/mnECqke

Thank you

Quick reply as I am short of time at the moment and I will look at the video later tonight.

Don't worry about the diesel age just yet.
Leave the levers connected together.
Use the engine start spray very very cautiously - only a short spray (a second or so at the most). This stuff can cause damage.

More later!

[thesauvage]

Quick Update:

I'm at the boat right now, and gave the engine a good spray with the starter fluid.

VIDEO: https://youtu.be/W1-te1gGIro


The engine started up and fired promptly, and died shortly after.

Fuel delivery seems to. be the Problem, right?

[Wotname]

Maybe fuel problem but are you sure the engine stop lever/cable isn't operated.

However right now I would be concerned that the low oil alarm didn't silence after the start.

I am presuming the alarm is the low oil pressure and you should get oil pressure immediately after starting.

If it was me, I would be pulling the engine stop lever to ensure it can't start, decompress the engine with the decompression levers and spin it over with the starter motor until you get oil pressure. If you can't, you have to troubleshoot that before starting (IMO). Kept the seacock closed while you do this as you don't want to be filling the exhaust with raw water form the seacock.

[thesauvage]

I have 3 small red indicator lights on the starting panel:

- Oil / Engine
- Water
- Charge

Whithin the short period the engine was running, only the CHARGE light was iluminated, and the beeping sound didn't go away.

The Engine kill switch is all the way in.

[Wotname]

Originally Posted by thesauvage

I have 3 small red indicator lights on the starting panel:

- Oil / Engine
- Water
- Charge

Whithin the short period the engine was running, only the CHARGE light was iluminated, and the beeping sound didn't go away.

The Engine kill switch is all the way in.

And was the Oil light illuminated before the engine started and then extinguished immediately after it started?

If so, then disregard what I said about the oil pressure.

[thesauvage]

Yes, Oil warning lamp goes off as soon as i push and hold the starter button, while the engine was running it remained off, too.

It is the Charge warning lamp that stayed on.

[a64pilot]

Very first thing, you said some water came out of the exhaust when trying to start.
Please before you do anything else. Close the seacock to the engine, reason is without it running it will pump enough water in the exhaust to flood the engine with water and may cause severe damage.
I would immediately close that valve and then with the engine spinning over, shoot a small shot of starting fluid into it, it will rattle and crank, then as it begins to die down hit it with another shot, it will rattle again and die back down.

I would be so worried about water in the engine that I would do the starting fluid thing to keep it running long enough to blow that water out, a couple of shots will do it.

As long as you do not have glow plugs, starting fluid if used properly won’t hurt a Diesel, I’ve done it hundreds of times on farm and construction equipment.
However if you have glow plugs do no use it without disabling them, see compression is what normally ignites the Ether just like fuel, except Ether ignites much easier, so easy that a glow plug will ignite it as soon as it comes into contact and the piston can be in the wrong part of the stroke and can be damaged.
In my opinion the proper way is to shoot a small shot when the engine is turning over, that way you can’t get a large dose into one cylinder all at once like you can if you shoot it before its turning over.
Yes that may take two people or a remote starting cable.

Trick is small shot, you can always add if needed, but can’t take away, so no shot is too small.

Most likely you have air in the system, using the starting fluid to get the water out may clear it, but it’s not a recommended way to bleed your fuel system. Some Yanmar’s will will self bleed, My old 1987 4JHE for instance will.

[Wotname]

A few things.

The starting rpm on your first video seems to just a little on the slow side suggesting a less than ideal battery voltage at the starter motor for whatever reason. No slow enough to be red flag but it could be faster. However that isn't your immediate problem - the starting fluid proves you have a fuel problem.

A64pilot has give you very good advice on how to use starting fluid properly. As an aside for other readers, the 2QM20 does not have glow plugs.

Also his assessment of air in the fuel system is likely to correct.

As for fresh fuel, you can rig up a can of fresh fuel and a hose to connect it directly to the input side of the engine mounted filter and gravity feed it to the injector pump. Bleed the filter though to the injector pump and then get the engine running with the starting fluid as described by A64pilot.

By the way, have you tired opening the throttle lever further than normal i.e. try it about half throttle or more.

Keep trying stuff and it will run! These are not complex engines.

[a64pilot]

The most important thing however, is close that seacock or you will hydrolock your motor, after it’s running, open it, it won’t hurt the impeller to run dry for a few seconds.