Do you let your engine cool down after motoring to your mooring? If so, how long do you let it idle and what prompts you to shut it down? If not, what makes you decide to quit cold-turkey? Share your cool secrets here, then vote in this week's Quick Quiz at the bottom of the home page.
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Dakota Jim Russell
Yep . . . Manual Recommends 5 Minutes
Yanmar manual recommends a 5 minute warm up and a 5 minute cool down . . . And why argue with the ?<grin> Jim
Yanmar manual recommends a 5 minute warm up and a 5 minute cool down . . . And why argue with the ?<grin> Jim
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Bob Fuller
Same thing
5 minute warm up, 5 minute cool down. I think the manufacturer probably knows what they're talking about.
5 minute warm up, 5 minute cool down. I think the manufacturer probably knows what they're talking about.
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Paul Akers
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Dave
warm-up
The stresses on a diesel are extreme ... best to ease into it and out of it... I start my engine and let it warm up while we prepare to leave the slip. When we return I leave it idling while we tie up and put her away ... 5 minutes go by quickly and we make the manual happy. and hopefully the engine too. 19 yrs old and still running strong ..
The stresses on a diesel are extreme ... best to ease into it and out of it... I start my engine and let it warm up while we prepare to leave the slip. When we return I leave it idling while we tie up and put her away ... 5 minutes go by quickly and we make the manual happy. and hopefully the engine too. 19 yrs old and still running strong ..
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Tim Schaaf
did 40% not read the manual?
I agree with the previous posts...five minutes to warm up and five to cool down, including when turning the engine off under way. But I am wondering...judging by the poll, can it be that fully 40% of our members have not read the manual, or choose to ignore it???????!!!!!!!!
I agree with the previous posts...five minutes to warm up and five to cool down, including when turning the engine off under way. But I am wondering...judging by the poll, can it be that fully 40% of our members have not read the manual, or choose to ignore it???????!!!!!!!!
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Dave
Heat Transfer
Regardless of what the manual says I'd like to know the technical reason for the recommendation? An engine at idle is still producing plenty of heat, enough to burn up the engine if insufficient cooling is provided!!! Most manufacturers also recommend not to let the engine idle too long without being under a load (i.e. in gear). When the engine is running under higher RPM's it reaches an equilibrium, the cooling water flow is increased to hold the temp. at say 160 degrees. At idle the thermostat still keeps the engine at 160 degree's so what difference does it make? I could see if the cooling water was left running after shutdown but that is not the case in an engine driven raw water and coolant pump. You certainly don't run your car engine at idle for a lengthy period to cool it off, what about deisel trucks? What are their groundrules?? Lot's of questions, hope theres some good answers out there. Dave
Regardless of what the manual says I'd like to know the technical reason for the recommendation? An engine at idle is still producing plenty of heat, enough to burn up the engine if insufficient cooling is provided!!! Most manufacturers also recommend not to let the engine idle too long without being under a load (i.e. in gear). When the engine is running under higher RPM's it reaches an equilibrium, the cooling water flow is increased to hold the temp. at say 160 degrees. At idle the thermostat still keeps the engine at 160 degree's so what difference does it make? I could see if the cooling water was left running after shutdown but that is not the case in an engine driven raw water and coolant pump. You certainly don't run your car engine at idle for a lengthy period to cool it off, what about deisel trucks? What are their groundrules?? Lot's of questions, hope theres some good answers out there. Dave
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Paul Akers
To Dave. What I've read...
...in the Yanmar manual: The five minutes beforehand (at start up) is to get the lubricants warmed up and circulating throughout the engine. This is self-explanatory. The five minutes before shut down is to prevent a buildup of heat. A burst of power, such as when you back down to stop forward momentum, can cause the heat to build up for a few minutes after the event. So by letting it idle before actual shut down will allow cooling water to circulate and offset the effects of any "burst" that may have been used. Sure hope this helps.
...in the Yanmar manual: The five minutes beforehand (at start up) is to get the lubricants warmed up and circulating throughout the engine. This is self-explanatory. The five minutes before shut down is to prevent a buildup of heat. A burst of power, such as when you back down to stop forward momentum, can cause the heat to build up for a few minutes after the event. So by letting it idle before actual shut down will allow cooling water to circulate and offset the effects of any "burst" that may have been used. Sure hope this helps.
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Ralph Johnstone
It's impossible not to .....................
5 minutes of idling the engine while loading your junk on the boat. 5 minutes of idling the engine putzing around getting the the sails up. 5 minutes of idling the engine while setting the anchor. 5 minutes of idling the engine while pulling the anchor off an ancient sunken logging chain. 5 minutes of idling the engine while motoring into the slip. I really don't see how you can avoid the warm up or cool down period. Regards, s/v Island Hunter
5 minutes of idling the engine while loading your junk on the boat. 5 minutes of idling the engine putzing around getting the the sails up. 5 minutes of idling the engine while setting the anchor. 5 minutes of idling the engine while pulling the anchor off an ancient sunken logging chain. 5 minutes of idling the engine while motoring into the slip. I really don't see how you can avoid the warm up or cool down period. Regards, s/v Island Hunter
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Terry Arnold
semi technical to Dave of Mystic
I agree that the thermostat (and waterpump) keep the exit coolant temperature at about the same temperature whether at load or idling. You have to look closer at the operating engine to see the reason for the mfg recommendation. An engine running at load has many times the heat transferred to the coolant as compared to an idling engine and the temperature gradient is much steeper and absolute temperature values in the head from combustion chamber surface to water jacket surface are much higher at load than at idle. Thus, if the engine is cut off suddenly from load condition, the local heat in the engine head adjacent to the combustion chamber will continue to be transferred to the coolant, but since the coolant is no longer circulating, can locally overheat. I demonstrated this by accident early in my ownership of a raw water cooled 2gm yanmar. If the engine is shut down suddenly after say running at 2800 rpm for a five or ten minutes or more and then restarted after only a few minutes, it screeches the high temperature alarm until enough water has circulated through the engine to bring the coolant temperature down at the location of the temperature sensor. Unnerving, especially until I figured out what was going on. Better follow manufacturer's recommendation I have a John Deere tractor also with a Yanmar engine and the manufacturer's recommendation for idling before shutdown is the same. Probably any engine that operates high on the power curve should be idled before shutdown.
I agree that the thermostat (and waterpump) keep the exit coolant temperature at about the same temperature whether at load or idling. You have to look closer at the operating engine to see the reason for the mfg recommendation. An engine running at load has many times the heat transferred to the coolant as compared to an idling engine and the temperature gradient is much steeper and absolute temperature values in the head from combustion chamber surface to water jacket surface are much higher at load than at idle. Thus, if the engine is cut off suddenly from load condition, the local heat in the engine head adjacent to the combustion chamber will continue to be transferred to the coolant, but since the coolant is no longer circulating, can locally overheat. I demonstrated this by accident early in my ownership of a raw water cooled 2gm yanmar. If the engine is shut down suddenly after say running at 2800 rpm for a five or ten minutes or more and then restarted after only a few minutes, it screeches the high temperature alarm until enough water has circulated through the engine to bring the coolant temperature down at the location of the temperature sensor. Unnerving, especially until I figured out what was going on. Better follow manufacturer's recommendation I have a John Deere tractor also with a Yanmar engine and the manufacturer's recommendation for idling before shutdown is the same. Probably any engine that operates high on the power curve should be idled before shutdown.
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Bryan C.
Engine rev?
I let my engine warm up and cool down, but before I shut it off I rev it to 3000 for about 3 secs. It blows out a big plume of black smoke and then clears. Some of it comes from racking it open, but engine seems to load up with carbon when it is sitting at idle for a few minutes. Manual does not say to do this, but I would think not blowing the crud out is worse. My engine runs clean whey I do this. Expert analysis?
I let my engine warm up and cool down, but before I shut it off I rev it to 3000 for about 3 secs. It blows out a big plume of black smoke and then clears. Some of it comes from racking it open, but engine seems to load up with carbon when it is sitting at idle for a few minutes. Manual does not say to do this, but I would think not blowing the crud out is worse. My engine runs clean whey I do this. Expert analysis?
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Roger Mummah
We Cool Her Down for 5 Min
We always let Endless Summer's good old Yanmar 2GMF cool down for a minimum of 5 minutes. Usually when we are anchoring there is an additional and variable time at or near idle. Of course we rev the diesel in reverse to set the hook, so we always allow an additional 5 minutes of cool down time after we are satisfied that we are well hooked.
We always let Endless Summer's good old Yanmar 2GMF cool down for a minimum of 5 minutes. Usually when we are anchoring there is an additional and variable time at or near idle. Of course we rev the diesel in reverse to set the hook, so we always allow an additional 5 minutes of cool down time after we are satisfied that we are well hooked.
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Chris Rice
New Engine-Rev then cool for 5 mins
I just installed a new Yanmar 40HP in my 40ft Hunter, the manual now says to rev the engine to full rpms in idle and then let cool for 5 mins. I haven't seen this mentioned in any of the previous posts, wonder if this is a new addition to the manual?
I just installed a new Yanmar 40HP in my 40ft Hunter, the manual now says to rev the engine to full rpms in idle and then let cool for 5 mins. I haven't seen this mentioned in any of the previous posts, wonder if this is a new addition to the manual?
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Duane Cady
2GMF rev before shutdown
I read somewhere (The manual maybe ??) that it is good to rev the engine in neutral to 3000 (for this engine) and shut it down from there. I think the rationale was to ensure all fuel in the cylinders was burnt off, making for cleaner cylinders, and exhaust jacket. Since the rev time is in neutral and very short duration, I would think the heat buildup would be negligible. Is this correct ?
I read somewhere (The manual maybe ??) that it is good to rev the engine in neutral to 3000 (for this engine) and shut it down from there. I think the rationale was to ensure all fuel in the cylinders was burnt off, making for cleaner cylinders, and exhaust jacket. Since the rev time is in neutral and very short duration, I would think the heat buildup would be negligible. Is this correct ?
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Tim Schaaf
Rev before shutting down
I also rev to 3000 for a few seconds after the cool down period and before shutting the engine off. This is also specified in the manual and is to blow out unburned fuel, carbon, etc. Make sure you do these things in the right order!
I also rev to 3000 for a few seconds after the cool down period and before shutting the engine off. This is also specified in the manual and is to blow out unburned fuel, carbon, etc. Make sure you do these things in the right order!
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Ken Hunter
Clean It Out
Yanmar says, and I agree, run engine at 3000 rpm for 1 minute prior to shut down. Cleans out excess carbon, fuel and cools engine to normal operating temp. Ken Hunter
Yanmar says, and I agree, run engine at 3000 rpm for 1 minute prior to shut down. Cleans out excess carbon, fuel and cools engine to normal operating temp. Ken Hunter
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Jim
Cool down Yes
I have the 3" heat exchanger so the engine runs at about 165-170 in the Chesapeake Bay's 75 degree water. When i pull into the slip I leave the engine running at idle until i get the rest of the lines on the boat. The Universal M25 takes about 5 minutes to cool down. Jim
I have the 3" heat exchanger so the engine runs at about 165-170 in the Chesapeake Bay's 75 degree water. When i pull into the slip I leave the engine running at idle until i get the rest of the lines on the boat. The Universal M25 takes about 5 minutes to cool down. Jim
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Al Sandrik
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Terry Arnold
Shutdown according to Yanmar 2gm Operating Manual
1. Stopping Procedure a. Place the clutch handle in the "neutral" position and idle the engine for 5 minutes. b. After five minutes' idling, place the speed control lever in the "full" position and raise the rpms to about 3600 to blow out any burnt gas in the cylinder. c. Set the engine to the lowest speed (about 850`900 rpm), cut the fuel, and stop the engine.
1. Stopping Procedure a. Place the clutch handle in the "neutral" position and idle the engine for 5 minutes. b. After five minutes' idling, place the speed control lever in the "full" position and raise the rpms to about 3600 to blow out any burnt gas in the cylinder. c. Set the engine to the lowest speed (about 850`900 rpm), cut the fuel, and stop the engine.
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Rob
What do A-4 owners do?
I let mine cool down for about 5 minutes, then rev it to about 2000 rpm for about 5 or 10 sec, then shut her down. The rev is to clear carbon deposits, to which the engine is prone. I'm interested to hear what others do. Rob
I let mine cool down for about 5 minutes, then rev it to about 2000 rpm for about 5 or 10 sec, then shut her down. The rev is to clear carbon deposits, to which the engine is prone. I'm interested to hear what others do. Rob
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