Latestarter1
Well-Known Member
Wetspot,
Look at page 90 if you have the same manual.
As I have worked in U.S. diesel industry pretty much all my life the term high idle is common to all U.S. diesel engine manufacturers, and many European.
A diesel engine governor provides power up to the setting for a specific engines power rating. However it does not shut the fuel off at RATED rpm, the governor is set to allow fuelling at a reduced level until the fuel is cut right back. From the point at which the engine reaches RATED speed/power to the point at which the engine ceases to rev is the governor DROOP. The governor DROOP varies from application to application I.E a gen set has 5% or almost isocronus. An automove engine can have 15% or more in order for the driver to put a gear shift in. Imagine going for an overtake and suddenly the revs hit a brick wall! Mechanical marine diesels have around 10%, Electronic engines less.
High idle as I explained earlier is exactly that, the highest rpm which the governor allows the engine to run at. Engine is not producing RATED power at this speed, however it is the #1 test in trouble shooting. Unless engine can make the high idle spec it will never perform under load.
Most diesel engines run happlily once warm at high idle, VM are a little more cautious and state engine should only be run at this condition for no more than three minutes.
I can understand the reluctance of any dealer to get into your problem as it is a bit of a poison pill. Installation has never been signed off as being in accordance with manufacturers guidelines so where are you asking them to start? Review your whole installation, rubbish it, give you a big bill and and snagging list and say they will come back when you have completed the reccomendations before even attempting to troubleshoot the motor. Been there and scars yet to heal.
IF your motor passes test #1 you need to go back to your installation manual.
One of the clues could be the previously failed turbo. The KKK turbo used by VM is made of junk metal. You likely have the curled up cast Mercruiser exhaust riser also junk. The manual says you NEED at least 11 inches from the top of the riser to the water line. Even this spec is bonkers, trailer launched boats with this riser flood turbo for a pastime. Two things happen if you are 11 inches or less, sea water comes back into the junk metal housing and eats it away. Point #2 the engine gets stangled by the exhaust a 11 inches or less, having tested engine for a job which was going legal we got over 5 inches of Hg back pressure once the riser was less than 11 inches above the water. Hot seawater plus very hot exhaust gas expands very quickly causing restriction. Unless your exhaust backpressure is less than 3 inches of Hg your engine is strangled.
I can understand yor frustration, however ripping into the base motor will not resolve your problem.
Look at page 90 if you have the same manual.
As I have worked in U.S. diesel industry pretty much all my life the term high idle is common to all U.S. diesel engine manufacturers, and many European.
A diesel engine governor provides power up to the setting for a specific engines power rating. However it does not shut the fuel off at RATED rpm, the governor is set to allow fuelling at a reduced level until the fuel is cut right back. From the point at which the engine reaches RATED speed/power to the point at which the engine ceases to rev is the governor DROOP. The governor DROOP varies from application to application I.E a gen set has 5% or almost isocronus. An automove engine can have 15% or more in order for the driver to put a gear shift in. Imagine going for an overtake and suddenly the revs hit a brick wall! Mechanical marine diesels have around 10%, Electronic engines less.
High idle as I explained earlier is exactly that, the highest rpm which the governor allows the engine to run at. Engine is not producing RATED power at this speed, however it is the #1 test in trouble shooting. Unless engine can make the high idle spec it will never perform under load.
Most diesel engines run happlily once warm at high idle, VM are a little more cautious and state engine should only be run at this condition for no more than three minutes.
I can understand the reluctance of any dealer to get into your problem as it is a bit of a poison pill. Installation has never been signed off as being in accordance with manufacturers guidelines so where are you asking them to start? Review your whole installation, rubbish it, give you a big bill and and snagging list and say they will come back when you have completed the reccomendations before even attempting to troubleshoot the motor. Been there and scars yet to heal.
IF your motor passes test #1 you need to go back to your installation manual.
One of the clues could be the previously failed turbo. The KKK turbo used by VM is made of junk metal. You likely have the curled up cast Mercruiser exhaust riser also junk. The manual says you NEED at least 11 inches from the top of the riser to the water line. Even this spec is bonkers, trailer launched boats with this riser flood turbo for a pastime. Two things happen if you are 11 inches or less, sea water comes back into the junk metal housing and eats it away. Point #2 the engine gets stangled by the exhaust a 11 inches or less, having tested engine for a job which was going legal we got over 5 inches of Hg back pressure once the riser was less than 11 inches above the water. Hot seawater plus very hot exhaust gas expands very quickly causing restriction. Unless your exhaust backpressure is less than 3 inches of Hg your engine is strangled.
I can understand yor frustration, however ripping into the base motor will not resolve your problem.
