Hi folks, I've never had a straight answer on this in six years of chartering and two weeks of ownership (maybe because it differs by engine). I now have a Yanmar SB8 diesel: should I warm it up by engaging forward or reverse gear, or leave it in neutral? The broker (ya,what do they know) swears up and down that you never warm a diesel without a load. The 25 year old manual however, says run at 1/4 throttle in neutral. Your expert opinion is appreciated... mav
how do you warm up a diesel engine
- Thread starter Mav
- Start date
- Status
The manual sounds about right
I'm no expert but I would believe the manual. Are you sure the broker didn't say never warm it up with a load? I had a Yanmar mechanic check out my engine when I had some questions and we warmed it up for at least 10 minutes at about 2,000 rpm in neutral before putting in gear. Scott
I'm no expert but I would believe the manual. Are you sure the broker didn't say never warm it up with a load? I had a Yanmar mechanic check out my engine when I had some questions and we warmed it up for at least 10 minutes at about 2,000 rpm in neutral before putting in gear. Scott
Check out this site.
Mav: Check out this site. Basically the raw water cooled engines should have a little warm up and then mild throttle. The fresh water cooled engines need almost no warm up. www.yanmarhelp.com
Mav: Check out this site. Basically the raw water cooled engines should have a little warm up and then mild throttle. The fresh water cooled engines need almost no warm up. www.yanmarhelp.com
Neutral
As far as I know you should warm up at around 1200 to 1500 RPM in Neutral for 10 minutes. The worst thing to do is run the engine at slow revs for long periods. When motoring always vary the speed from time to time. Its also good to run the engine at Maxium revs ( under power ) towards the end of your trip, this is good for the engine and also leaves plenty of lubrication for long shutdowns.
As far as I know you should warm up at around 1200 to 1500 RPM in Neutral for 10 minutes. The worst thing to do is run the engine at slow revs for long periods. When motoring always vary the speed from time to time. Its also good to run the engine at Maxium revs ( under power ) towards the end of your trip, this is good for the engine and also leaves plenty of lubrication for long shutdowns.
Here's consistency
All that is consistent with what I was told by original owner, and the Yanmar mechanic: warm up at low rpm (1200)for ten minutes or so, then take off at gradually increasing rpm. You will get advocates for running at low rpm versus high rpm as what is best for long term care. The Yanmar mechanic says the engines were designed to run at high RPMs for long periods. Then there is always the question of whether your tachometer is accurate... anyway Then before shutting down, run at high rpm briefly. I agree with Wayne. One characteristic of the engine is that if you run it consistently at too low rpm levels, you will get a soot buildup in the exhaust elbow joint. That's a maintenance point neglected sometimes. Needs either cleaning after 400 hours, replacing after 1000-1200, I was told. If you don't, it can clog and blow the hoses, and burn holes in the muffler, and spew soot all over the interior. Yep, it happened to me about one month after I bought the boat. A really big mess you don't want. Good luck, Sanders
All that is consistent with what I was told by original owner, and the Yanmar mechanic: warm up at low rpm (1200)for ten minutes or so, then take off at gradually increasing rpm. You will get advocates for running at low rpm versus high rpm as what is best for long term care. The Yanmar mechanic says the engines were designed to run at high RPMs for long periods. Then there is always the question of whether your tachometer is accurate... anyway Then before shutting down, run at high rpm briefly. I agree with Wayne. One characteristic of the engine is that if you run it consistently at too low rpm levels, you will get a soot buildup in the exhaust elbow joint. That's a maintenance point neglected sometimes. Needs either cleaning after 400 hours, replacing after 1000-1200, I was told. If you don't, it can clog and blow the hoses, and burn holes in the muffler, and spew soot all over the interior. Yep, it happened to me about one month after I bought the boat. A really big mess you don't want. Good luck, Sanders
Dont apply more than lowmoderate throttle ........
until the engine comes up to *normal operating temperature* - ANY engine. A cold combustion chamber will result in incomplete combustion and will produce a lot of soot - which may eventually plug up the wet exhaust system and water injection elbow, etc. Simply dont 'trounce' it until the temp. gauge indicates 'normal' temperature - simply WATCH THE GAUGE. No other 'recipies' needed. ;o)
until the engine comes up to *normal operating temperature* - ANY engine. A cold combustion chamber will result in incomplete combustion and will produce a lot of soot - which may eventually plug up the wet exhaust system and water injection elbow, etc. Simply dont 'trounce' it until the temp. gauge indicates 'normal' temperature - simply WATCH THE GAUGE. No other 'recipies' needed. ;o)
My Manual...
is for a 3GM, 2GM, 1GM and 3HM. It says to warm up the engine in neutral for 10 mins @ 500rpm or 5 mins @ 1000rpm before engaging the gears.
is for a 3GM, 2GM, 1GM and 3HM. It says to warm up the engine in neutral for 10 mins @ 500rpm or 5 mins @ 1000rpm before engaging the gears.
My YSE8 manual says....
to warm up for 5 minutes in neutral. The manual doesn't mention rpm. The YSE8 (single cyl., 8hp)is similar to your SB8.....it just preceded it by a few years. Kevin
to warm up for 5 minutes in neutral. The manual doesn't mention rpm. The YSE8 (single cyl., 8hp)is similar to your SB8.....it just preceded it by a few years. Kevin
great feedback
Thanks for the great feedback, everyone. The broker very clearly stated warm up in gear, but my manual and everyone else's feedback is to the contrary so I'm with you. Great input on other aspects of running this engine that's new to me. I can't help but be amazed at how feedback on this question has flowed in from corners all over the world, in the space of 24 hours. Thanks again.
Thanks for the great feedback, everyone. The broker very clearly stated warm up in gear, but my manual and everyone else's feedback is to the contrary so I'm with you. Great input on other aspects of running this engine that's new to me. I can't help but be amazed at how feedback on this question has flowed in from corners all over the world, in the space of 24 hours. Thanks again.
Seems counter productive
I suppose it's a moot point anyway from the messages above, but.... It seems to me that the broker's advice is counter intuitive and sort of wacky. I always tend to think of "warming up" as getting the engine started *before* going anywhere. Warming it up in gear implies to me that you're going somewhere. The part that's wacky to me is, how do you warm up an engine in gear, anyway? Maybe if you're in a slip, but how about on a mooring? I can just imaging a boat going round a mooring in circles trying to warm up the engine...
I suppose it's a moot point anyway from the messages above, but.... It seems to me that the broker's advice is counter intuitive and sort of wacky. I always tend to think of "warming up" as getting the engine started *before* going anywhere. Warming it up in gear implies to me that you're going somewhere. The part that's wacky to me is, how do you warm up an engine in gear, anyway? Maybe if you're in a slip, but how about on a mooring? I can just imaging a boat going round a mooring in circles trying to warm up the engine...
running at anchor
I have a C320 with a Perkins 30. If I am running the engine at anchor to charge batteries, I put it in reverse at about 1200 rpm for 20 minutes. I have been told by several diesel mechanics over the years to run a diesel under load. I do the same at the docks. I was also told to let the engine cool off after a hard run. If the "experts" can't agree on what to do, what is the average sailor to do?
I have a C320 with a Perkins 30. If I am running the engine at anchor to charge batteries, I put it in reverse at about 1200 rpm for 20 minutes. I have been told by several diesel mechanics over the years to run a diesel under load. I do the same at the docks. I was also told to let the engine cool off after a hard run. If the "experts" can't agree on what to do, what is the average sailor to do?
Warm Up
Here's what I do. Start the engine, let it warm up in neutral at idle while I unhook shore power, cast off the dock lines, etc...then I put it in gear (reverse), back out of the slip, then put it in forward...all this is done at idle, the RPM never changes. I have to idle about 10 min to get out of my cove, by then it is warm. I do not think it makes that much difference whether it is warmed up in neutral or in gear...the RPM will not change that much, and there is not that much "load" on it at idle.
Here's what I do. Start the engine, let it warm up in neutral at idle while I unhook shore power, cast off the dock lines, etc...then I put it in gear (reverse), back out of the slip, then put it in forward...all this is done at idle, the RPM never changes. I have to idle about 10 min to get out of my cove, by then it is warm. I do not think it makes that much difference whether it is warmed up in neutral or in gear...the RPM will not change that much, and there is not that much "load" on it at idle.
The main purpose of warming up.
The main purpose to warming up is to get the oil warmed and pumped throughout the engine at a level temperature. Warming it up under load puts an unnecessary load on the engine. After about 2 minutes of warming up in neutral, you will hear the engine "settle down" as the oil heats and reaches all of the engine spaces. You never want an engine to stall while you are in tight quarters and trying to maneuver the boat. That is why the gas engines are warmed up also. Then when you return to the dock, maneuvering procedures may cause you to "throttle up" in reverse. In a diesel, this burst will generate higher heat than a gasoline engine. It needs to cool down before the engine is shut off. When back in the slip, mooring, etc., let the diesel engine idle for about 5 mins so that the engine will cool down to normal levels before shutting it off.
The main purpose to warming up is to get the oil warmed and pumped throughout the engine at a level temperature. Warming it up under load puts an unnecessary load on the engine. After about 2 minutes of warming up in neutral, you will hear the engine "settle down" as the oil heats and reaches all of the engine spaces. You never want an engine to stall while you are in tight quarters and trying to maneuver the boat. That is why the gas engines are warmed up also. Then when you return to the dock, maneuvering procedures may cause you to "throttle up" in reverse. In a diesel, this burst will generate higher heat than a gasoline engine. It needs to cool down before the engine is shut off. When back in the slip, mooring, etc., let the diesel engine idle for about 5 mins so that the engine will cool down to normal levels before shutting it off.
- Status