Polarsailor
Member
Advice would be very appreciated.
I have a Yanmar 2GM20, raw water cooled and it has run 2700 hours.
I've had the boat 10 years and the engine has generally been totally fine. A few weeks ago it suddenly started putting out lots of white smoke. I limped back to my mooring and systematically checked the engine. The water injection exhaust elbow had failed, the weld had failed on the inner tube. Unfortunately I snapped off one of the bolts removing the elbow. After a few attempt had to take the head to an engineers to get the bolt drilled out and helicoiled.
As I had the head off I reground the valves, cleaned out the waterways and generally serviced the head although did not remove the injectors. The valves were reground. The inlet were really good but the exhaust vales were slightly pitted even after grinding Put the head back together and ran the engine. New gaskets used throughout. The bores looked fine, no scores and minimal lipping at the top of the bores.
It started easily and ran really well in fact better than before, as I had done the tappets which needed doing. At low speed up to about quarter power the engine produces little smoke. However under load the engine produces increasingly more white smoke. More than before.
If I carefully remove the rocker cover oil filler I get some white smoke coming out. This would suggest to me that the exhaust valves are not sealing too well ( I did not replace the valves, seals or guides)?
1. What is likely to be causing the white smoke - poor valve seals?
2. Could poor valve seals be lowering the compression leading to unburnt fuel being exhausted?
3. The engine has only been run for 2h after re-building is it likely to improve as it is run in?
If I hold my hand over the exhaust it smells oily but no really that much of diesel.
I have a siphon fitted between the thermostat and water injection elbow. At the top of the siphon is a very small tube that I had not noticed before I rebuilt the engine. This small pipe may be a tell-tale? I don't think any water use to flow through the small pipe but I now have a steady stream, is this correct? Are these siphon fitted with a non -return valve? The volume of water is running into my bilge and is quite substantial... has anyone seen one of these units before?
Any thoughts gratefully received!
Keiron
I have a Yanmar 2GM20, raw water cooled and it has run 2700 hours.
I've had the boat 10 years and the engine has generally been totally fine. A few weeks ago it suddenly started putting out lots of white smoke. I limped back to my mooring and systematically checked the engine. The water injection exhaust elbow had failed, the weld had failed on the inner tube. Unfortunately I snapped off one of the bolts removing the elbow. After a few attempt had to take the head to an engineers to get the bolt drilled out and helicoiled.
As I had the head off I reground the valves, cleaned out the waterways and generally serviced the head although did not remove the injectors. The valves were reground. The inlet were really good but the exhaust vales were slightly pitted even after grinding Put the head back together and ran the engine. New gaskets used throughout. The bores looked fine, no scores and minimal lipping at the top of the bores.
It started easily and ran really well in fact better than before, as I had done the tappets which needed doing. At low speed up to about quarter power the engine produces little smoke. However under load the engine produces increasingly more white smoke. More than before.
If I carefully remove the rocker cover oil filler I get some white smoke coming out. This would suggest to me that the exhaust valves are not sealing too well ( I did not replace the valves, seals or guides)?
1. What is likely to be causing the white smoke - poor valve seals?
2. Could poor valve seals be lowering the compression leading to unburnt fuel being exhausted?
3. The engine has only been run for 2h after re-building is it likely to improve as it is run in?
If I hold my hand over the exhaust it smells oily but no really that much of diesel.
I have a siphon fitted between the thermostat and water injection elbow. At the top of the siphon is a very small tube that I had not noticed before I rebuilt the engine. This small pipe may be a tell-tale? I don't think any water use to flow through the small pipe but I now have a steady stream, is this correct? Are these siphon fitted with a non -return valve? The volume of water is running into my bilge and is quite substantial... has anyone seen one of these units before?
Any thoughts gratefully received!
Keiron