I recently purchased a 2003 56 Sedan Bridge with Man 1050 engines with block heaters controlled by the breaker panel. They do not have a thermostat for the ambient temperature but will only heat the block up to 120 degrees then maintain the temp Curious as to when I should turn the heaters on? Obviously I will run them ~12 hours before running the boat especially if it’s on the colder side outside but what if I’m not planning on running the boat but it’s below 40 degrees, should I run the heaters? keep in mind I am NOT depending on the block heaters for bilge heat as I have two boat safe heaters on thermostats for that I don’t mind paying the electric bill to run the block heaters when necessary but would rather not put the wear and tear on them of running all the time and paying for that power if it isn’t needed
IMO, turn them on 1 hour before starting when engine room is below 70 degrees. They offer nothing if you are not going to run them. Make sure you turn them off when the mains start.
Quote from the HotStart install manual; To avoid heater damage, disconnect power to heater before starting engine. I'm sure others have their own routine that differs from this, but when in doubt, quote the manual..
There have been several debates and threads on this. Prepare to get opinions on every end of the spectrum. I only use mine 24 hrs or so before starting engines. Others are going to tell you to leave them on except when running to keep moisture and condensation out of the engines. I worry more about an electrical fire from leaving them on continuously then I do about moisture in the engines and I’m in a rainforest- literally.
Don’t rely on boat safe heaters or any electric heat …for winterizing . Loss of power , which does and will happen sometime, will kill your systems ( motors) etc. Winterize , break out the pink champagne!!! Pour away! And I don’t care what BS name they have on them , there is no safe un attended boat heater. 6-8 hours on the block heaters would be a good safe call, below 60 degrees, IMO. They should start on there own above that , IMO. Fancy as they are.
I live about 5 minutes from the boat and in a fairly moderate climate, I’ll be aware of any power failure in the rare times it’s cold enough to matter much
Curious as to why some feel a block heater is needed? I've ran diesels (John Deere, Cat, DD, Yanmar, Cummins) in tractors and earth moving equipment in the mid-west (real winter and cold temps) and rarely needed a block heater. -20 F yes, a block heater is needed to let the engine crank but that's about it. Keep in mind, most of these engines go 10,000 hrs between MOH and do it at rated RPMs. Is this something pertaining to MAN engines? Never owned one so I am curious.
Cat dealer in north Carolina wants them left on, except when running. Prevents condensation in motor. That condensation and resulting rust are real bad for the motor. Heavy equipment like excavators would also benefit from them. They last longer because they're derated unlike rec motors. Your tractors owners manual will detail what severe use is. Sitting cold for 24hrs between starts is first on the list. Oil is no longer on cylinder walls and condensation is present. Do you want your cylinder walls to look like the outside of your soda can on a hot summer day? I don't.
I've rebuilt so many tractor diesels I can't count them. Never seen anything like what you are suggesting. When pulling an engine down the internals have a film of oil on them, even after sitting for a long period, as in months. I can't think of anyone I know that has experienced what you have seen. Perhaps its the "wet" environment of a boat?
My apologies, but I assumed your area dipping below the 40s is flirting with 32 and below…. Nice you are so close to your boat. IMO, I’m not a fan of any heaters running unattended, ok if you are physically on board while they are on. I do not run block heaters on my small Detroit’s . I also never start/run them below freezing, by then I have them winterized . Where they sit for 3 months, un heated. I find it hard to believe 40 wt. oil is going wash away from the internal parts and rust.Plus I run Lucas oil stabilizer, which I believe works… I’m running the boat today ,currently 43 degrees, my port motor fires right up. Starboard needs massaging, but I get it to start also. That one is due for a rebuilt some day. Running where? Over to the Travel Lift dock to fill my water tank. We are still using the boat every weekend and they turned off my dockside water. Lol.
Cold motor, air warms up during the day, humidity in air condenses on cylinder walls, light rusting of walls. Didn't say it is life changing, just what manufacturer recommends and as an engineer, makes sense. My heavy equipment doesn't have the luxury of being plugged in, sits on jobsite until run, and shut off again. Read owners manual for severe duty applications. Oil leak down is where most wear occurs. The first seconds of operation before oil is sprayed on internal parts by oil pump create the most wear. Why do very large motors have pre oilers? Drastically reduces wear during start up.
For about $100 you can get a power and temp monitor that will alert you if power is lost or temp drop (or exceed) whatever limits you pick. Look up MySpool I use two of them on the boat i run, one to monitor a large chest freezer and the second one to monitor chiller loop temp. I get text and email alerts as if limits are exceeded or if power is lost. And when it comes back on too. Within seconds of disconnecting power when switching shore/gen my phone chirps. only thing obviously is that you need an internet connection (cell or wifi) and you router needs to have a battery back up (computer style UPS).
You may be right, I am just going by what I have experienced first hand during overhauls. I do know that in days of old oils did not stay on internal parts very well but today's oils and additives really are a new breed of amazing. With that said,,, I still like an oil heater for really cold climates. By the way,,, great to see another engineer here!
Cold start is when most engine wear occurs, then a warmer engine temp would wear less. That's my opinion , my block heaters on always on and factory set to 120 degrees.
I also leave them on all the time when not running. I just changed out the thermostats and wires to 90 degrees from 120. I didn't realize I had 120-degree thermostats when ordering replacements from Hotstart. I can't compare them to the originals because they weren't functional when I bought the boat, but 90 degrees seems to work fine. I boat mostly in NY and New England. I think you'll get different opinions based on geography. My last boat had Cummins engines and I used block heaters all the time for almost twenty years. My personal opinion is that engine room stays more rust free, and engines start instantly with no smoke.
