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Thread: 400 watt engine compartment heater

  1. #1
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    Default 400 watt engine compartment heater

    This is an overlap with the coolant pump thread but I’m curious if anyone has any experience with this heater. It seems to be designed for heating a boat’s engine compartment to prevent freezing and to facilitate cold starting.
    It’s only 5” x 5” x 9”, 400 watts AC.

    https://www.westmarine.com/buy/cafra...stat--12960282

    6DC2CFD6-65B2-488A-AB64-8ECD6B71500D.jpeg

  2. #2
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    Default Re: 400 watt engine compartment heater

    No experience to offer but FWIW it gets really good reviews on Amazon.

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    Default Re: 400 watt engine compartment heater

    I hang a 100W light bulb in my engine compartment all winter. That seems to be enough, no freezing and the engine starts okay.

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by J.Madison View Post
    I hang a 100W light bulb in my engine compartment all winter. That seems to be enough, no freezing and the engine starts okay.
    ..... I feel like I am living in the wrong place.... more than 100 W here...


  5. #5
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    Default Re: 400 watt engine compartment heater

    this really fits the aesthetic of your boat ron?

    Simpler is better, except when complicated looks really cool.

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by Paul Pless View Post
    this really fits the aesthetic of your boat ron?
    Errrrm,... it’s in the engine room Paul.

  7. #7
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    Default Re: 400 watt engine compartment heater

    You might look at ceramic infrared heating elements they come in many shapes and sizes, we use one it our well house controlled with a timer to keep the pressure tank and above ground piping from freezing.

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    Default Re: 400 watt engine compartment heater

    The most danger with any electric heating system (a 100 watt light bulb will keep the engine from freezing) is the loss of electrical power. Get a severe ice storm with snapped power lines and all your attempts at preventing freezing would be for nothing.

    Drain the block and manifolds each time you are done for the day in the winter. It will be time well spent. By the way you can check for propane heaters here https://wisepick.org/best-propane-garage-heater/
    Last edited by Serhij; 10-25-2018 at 10:09 PM.

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    Default Re: 400 watt engine compartment heater

    Mark0,

    I have the same Jotul keeping me warm tonight!

    Quote Originally Posted by Mark0 View Post
    ..... I feel like I am living in the wrong place.... more than 100 W here...

    Last edited by Tom Christie; 10-25-2018 at 02:08 AM.

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by Serhij View Post
    The most danger with any electric heating system (a 100 watt light bulb will keep the engine from freezing) is the loss of electrical power. Get a severe ice storm with snapped power lines and all your attempts at preventing freezing would be for nothing.


    Drain the block and manifolds each time you are done for the day in the winter. It will be time well spent.
    Freezing the engine really isn’t an issue here. It rarely gets that cold in the saltwater marina. Plus the engine coolant has antifreeze and the engine keel cooler pipe actually acts as a keel warmer in winter. The purpose of the engine room heat is to facilitate cold starting and also to drive a little moisture out of the boat.

  11. #11
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    Default Re: 400 watt engine compartment heater

    Ron II,

    I am not familiar with that heater.
    I read the specs and it looks okay.
    But I would put a block heater in the engine instead.
    The engine will radiate the heat throughout the engine room
    while keeping the engine much warmer for gentler cold starts.
    Further reducing wear on the engine, starter, and battery.
    And, shorter warm-up times.
    You could easily wire it to a thermostat for added on/off control.
    Some blocks will accept two heaters.
    I did two on an old Datsun 510 once in Calgary for freezing cold winters.
    It would blow warm interior air on start-up when it was -30 below F!

    Cheers
    Last edited by Tom Christie; 10-25-2018 at 02:06 AM.

  12. #12
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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by Tom Christie View Post
    Ron II,

    I am not familiar with that heater.
    I read the specs and it looks okay.
    But I would put a block heater in the engine instead.
    The engine will radiate the heat throughout the engine room
    while keeping the engine much warmer for gentler cold starts.
    Further reducing wear on the engine, starter, and battery.
    And, shorter warm-up times.
    You could easily wire it to a thermostat for added on/off control.
    Some blocks will accept two heaters.
    I did two on an old Datsun 510 once in Calgary for freezing cold winters.
    It would blow warm interior air on start-up when it was -30 below F!

    Cheers
    I totally agree about the block heater, and in fact have had one in this boat for years and it does the job wonderfully. The problem is that on my particular engine, the block heater can only go into a receptacle that is extremely hard to get at to change. And unfortunately the block heaters only last a couple of years before burning out. In the past I have struggled to change them, dropping wrenches into the bilge, and busting my knuckles until they are a bloody mess and just getting extremely frustrated with the process. I've decided that I'm too old for that kind of aggravation any more so I'm looking for alternatives. But yes, for anyone else who can more easily access the block heater location, it is the best way to go.

  13. #13
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    Default Re: 400 watt engine compartment heater

    There are also oil-pan heaters which have a magnetic sole, and thus attach themselves under your engine. I use one for a 1939 tractor.

    https://www.princessauto.com/en/deta...er/A-p4270099e

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by Dave Hadfield View Post
    There are also oil-pan heaters which have a magnetic sole, and thus attach themselves under your engine. I use one for a 1939 tractor.

    https://www.princessauto.com/en/deta...er/A-p4270099e
    Wow, that looks promising. Not what I thought these things looked like. I thought they were soft pads that would probably eventually fall off into the bilge. Thanks for the link. I wonder if that would work if stuck to a water jacket on the front of the engine instead of the oil pan.

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by ron ll View Post
    Wow, that looks promising. Not what I thought these things looked like. I thought they were soft pads that would probably eventually fall off into the bilge. Thanks for the link. I wonder if that would work if stuck to a water jacket on the front of the engine instead of the oil pan.
    Is it something you can leave in place and run all the time? Looks like maybe it's designed for engine pre-heat but not for continuous use.

  16. #16
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    Default Re: 400 watt engine compartment heater

    The smaller ones, 200W don't turn out all that much heat, but enough I think.

    I presume you can run them continuously, but yes, they are generally switched on in the evening so that the engine will start in the morning.

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    Default Re: 400 watt engine compartment heater

    FWIW, a common method of dealing with this problem in the commercial lobsterboat fleet in SW Nova Scotia, where the lobster season runs from November to May, is to install an electric in-line heater and pump in the engine's coolant system, illustrated in the schematic below. When the boat is idle at the wharf, bypass valves are opened, isolating the keel cooler. The shore power runs the circulating pump and heater, which warms the engine coolant and circulates it within the engine and, via a heat exchanger, to the interior spaces (usually the wheelhouse and accommodations). The warm engine block radiates heat into the engine room. When the crew arrives to take the boat out, the heater and circulating pump breakers are turned off, the shore power is disconnected, the bypass valves are opened, and the warm engine is started. This system doesn't keep the interior spaces at shirt-sleeve temperature in -10 deg. C. weather, but comfortably above freezing. The common heater capacity is 1500 watt for a 600-hp Caterpillar and about 2000 cubic feet of interior.

    Generic engine cooling schematic.jpg
    Hope for the best, but plan for the worst.

  18. #18
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    Default Re: 400 watt engine compartment heater

    In the earlier related thread I was asking about this and still may use this system. In my case, I have an engine coolant loop which runs thru the domestic water heater tank. At the dock, the domestic water tank is kept hot by shore power 24/7. So the thought is to simply add the circulation pump. The question I have is why doesn’t it circulate the heat naturally thru convection? I’m thinking maybe the engine thermostat prevents that, in which case it would probably prevent it with a pump as well.

  19. #19
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    Default Re: 400 watt engine compartment heater

    OK, if I have a point here, which is what Chris already said, it is that the OP's heater sounds good and the magnetic heater sounds like it is strictly for a relatively quick warm up, not something to be left unattended for a long time. I also think that a light bulb is an idea that can be improved on for both safety and reliability.

    Quote Originally Posted by Dave Hadfield View Post
    There are also oil-pan heaters which have a magnetic sole, and thus attach themselves under your engine. I use one for a 1939 tractor.

    https://www.princessauto.com/en/deta...er/A-p4270099e
    Quote Originally Posted by cstevens View Post
    Is it something you can leave in place and run all the time? Looks like maybe it's designed for engine pre-heat but not for continuous use.
    I tend to think that Dave is right.
    This heater produces a surface temperature up to 400°C
    http://www.tcforensic.com.au/docs/article10.html
    Reactions to temperature exposure
    Reaction
    Temperature (Celsius)
    Wood slowly chars*
    120°-150°
    Decayed wood ignites
    150°
    Ignition temp of various woods
    190°-260°
    Paper yellows
    150°
    Paper ignites
    218°-246°
    Oil soaked lagging ignites
    190°-220°
    Leather ignites
    212°
    Hay ignites
    172°
    Coal ignites
    400°-500°
    * wood chars at a rate of approximately 30-50 mm/hour
    Back to the 100 watt light bulb. I had a summer job in a maintenance department. The boss had been there for a while and had me replace the 240 volt pilot light bulb that he had installed on a 120V circuit 20 years ago. He liked 240 V bulbs in 120V applications like that because that was the typical life in his experience. I suppose they might be on their fourth bulb by now. After 45 years, I finally got around to the math. Running a bulb at half of its rated voltage cuts the wattage to a quarter of the rated wattage.

    I would want to stick with rough service bulbs and they are not readily available over 100W. For the same heat output as a 100W bulb, you need four 100W 220V bulbs. You could hook up some Quartz halogen 120V 1000W bulbs in series, but that might shorten the bulb life.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  20. #20
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    Default Re: 400 watt engine compartment heater

    Ok, so I'm curious now. Since I'd like to install a block heater on the 3-71 in Skookum Maru I did some research. The Phillips application listing for DD 3-71 has this to say:

    Watt: 750; Volt: 120; Diameter: Plate; Type: Immersion; Installation Information: Replaces water jacket access plate on side of engine. Available Service Parts: Hex Nut (8602999), Element Gasket (8603650). (Do not use 1000 watt heater).
    And the photo of it clearly shows that it comes with a plate that replaces the existing access plate. However Ron, in reading through some old threads here I found this old post from you:

    Quote Originally Posted by ron ll View Post
    I installed a 120v 250W block heater in my 3-71 and it is without a doubt the best thing I have ever done for that engine. I run it 24/7 except in the summer. But I am in Seattle, I'm surprised you would need it in Florida. But in my boat, it makes it a lot easier to start, doesn't blow as much smoke in the first few minutes of running, and generally keeps moisture down in the boat.

    Mine looks like this:
    http://www.ebay.com/itm/Perkins-Dies..._Parts&vxp=mtr

    There are several two-bolt "lozenge" shaped metal cover plates on the block of most 71's. I removed one of these and had a machine shop make a similar plate with a threaded hole for the block heater. On mine, it is kind of near the oil pump.
    From which appears that you used a generic heater element in a custom plate rather than one made for that application. So now I'm wondering if there isn't some place you could put that heater element that would be more easily accessible? I don't have access to a service manual or the actual engine right now so I can't determine where the "water jacket access plate" is on a 3-71, but it seems like it might be worth doing a little more investigation before abandoning that option entirely?

    Also, if it's at all useful I'd be happy to try my hand at removing the bad unit from the engine in Snoose. I have a lot of experience in removing bits of engines in impossible places...

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    Default Re: 400 watt engine compartment heater

    I bought the heater shown in the OP, but I think I’ll return it before installing it. It’s a nice unit for its intended purpose, which is preventing engine freezing, but not really suitable for what I need. It has a thermostat which only turns the heater on at 41 F and below (the temp inside a refrigerator). It’s not very often my boat’s temp gets that low so it would hardly ever turn on. My old block heater would run constantly all fall, winter and spring, making the engine easier to start and keeping the boat just slightly warmer than outside all the time, thereby helping evacuate moisture. This heater won’t do that. Bummer.

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    Default Re: 400 watt engine compartment heater

    is it possible to access a different freeze plug where you could install a generic type block hheater ??

    also, if you could run your heater on a timer for say a few hours a day instead of constantly, surely you would double or triple the service life.. no ?


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    Default Re: 400 watt engine compartment heater

    I really wish I could find a better spot for the block heater, but I’ve looked at the whole engine to no avail. I’m now back to thinking about a circulation pump on the hot water tank loop. Or maybe at this point it is worth hiring someone younger, more flexible and with more patience than I to change out the existing block heater.

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    Default Re: 400 watt engine compartment heater

    Or a new thought; maybe I’ll bite the bullet and wrestle the existing one out with whatever the cost to body and psyche, then design and build a specialized tool for reinstallation and future change outs. A socket or box wrench won’t go on it due to adjacent obstructions, so a custom tool would have to grip it differently.

  25. #25
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    Default Re: 400 watt engine compartment heater

    Tractor Supply lists a 90w 120vAC 24-in dipstick heater that will keep your oil in the sump warm. You can always put a timer on the power supply.
    Hope for the best, but plan for the worst.

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by mmd View Post
    Tractor Supply lists a 90w 120vAC 24-in dipstick heater that will keep your oil in the sump warm. You can always put a timer on the power supply.
    A good thought, but the existing block heater is (was) 400 watts. Not sure 90 watts would get me there.

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by ron ll View Post
    Or a new thought; maybe I’ll bite the bullet and wrestle the existing one out with whatever the cost to body and psyche, then design and build a specialized tool for reinstallation and future change outs. A socket or box wrench won’t go on it due to adjacent obstructions, so a custom tool would have to grip it differently.
    It definitely seems like the block heater is the best option if you can solve the install/replacement problem. Let me know if I can help at all Ron. I'm happy to bash my knuckles on Snoose and I'll probably learn something that would help me on Skookum Maru. Might also be worth talking to an experienced Detroit mechanic to see if they have any thoughts? I can recommend George Gemmill, the guy who did the mechanical survey on Skookum Maru. His knowledge of older DDs was pretty impressive. Ping me if you want contact info.

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    Default Re: 400 watt engine compartment heater

    I like the idea of putting a heater with timer or thermostat in the hot water loop, if that carries any weight at all. Refer to my schematic in Post 17.
    Hope for the best, but plan for the worst.

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by mmd View Post
    I like the idea of putting a heater with timer or thermostat in the hot water loop, if that carries any weight at all. Refer to my schematic in Post 17.
    I like that too, and is near the top of the list. My hesitation is that there is currently an engine coolant loop thru the domestic hot water tank which shore power keeps heated. Why doesn’t this circulate naturally thru convection? Is it because the engine thermostat blocks it? And if so, wouldn’t it also block it if a pump were added?

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    Default Re: 400 watt engine compartment heater

    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by MN Dave View Post
    Any help?
    Maybe. But location 71 on that diagram is where my existing block heater is, and I don’t think I have a port at location 53. All DDs are slightly different configurations. But I’ll check again when I go down to the boat today.

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    Default Re: 400 watt engine compartment heater

    ^^^ I'd assume that the "53" indicates where it would be installed on a 53 series motor. So it sounds like you have it installed at the correct position for a 71 series, but it's just a PITA to access that spot with the configuration you have.

    EDIT: Looks like that port is on the intake side of the block. I'm guessing the main problem is that it's behind the intake silencer? Would it be more accessible if you pulled the silencer housing?

  33. #33
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    Default Re: 400 watt engine compartment heater

    It’s behind the intake manifold, the oil filler, the dipstick housing, and generally behind everything on that side of the engine.

  34. #34
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    Default Re: 400 watt engine compartment heater

    Back to the coolant loop, here is what my water heater tank looks like. The center loop is the shore power 120v heating element, and the other three longer loops are the engine coolant which heat water underway. So while on shore power it seems like this could heat the engine if it circulated. So does it not circulate naturally because the engine coolant inlet and outlet both have equal pressure when heated so convection won’t “rise”? Or is it not circulating because the engine thermostat blocks it? If the former, maybe simply adding a circulation pump will work.

    6F7D7CDF-5D53-46F0-9500-9FDD22C8AE2A.jpeg

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    Default Re: 400 watt engine compartment heater

    Quote Originally Posted by ron ll View Post
    I like that too, and is near the top of the list. My hesitation is that there is currently an engine coolant loop thru the domestic hot water tank which shore power keeps heated. Why doesn’t this circulate naturally thru convection? Is it because the engine thermostat blocks it? And if so, wouldn’t it also block it if a pump were added?
    Just remove the thermostat? Maybe not if your using the boat, you'd have to put it back in whenever you go out. Then again, that's pretty easy.

    I seem to remember that thermostats have a small hole it them so that there is always some small amount of circulation. With a 120V circulation pump from a furnace installed that hole should allow enough flow to keep things warm.

    I think I suggested that in the other thread.

    https://www.ebay.com/bhp/water-circulation-pump
    Last edited by Gib Etheridge; 11-01-2018 at 12:19 PM.

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