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DIY sump/ oil pan heater

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  • DIY sump/ oil pan heater

    Winter is soon upon us so I've decided it is time for a fitting a suitable oil pan heater. I do not wish to go for the pad type that is stuck on to the sump. They are rather expensive in the UK and I doubt whether they will stay on for long.

    I recently fitted PTC (positive temperature coefficient) heaters to my towel radiators and think these will work very well as oil pan heaters in our Smart engines.
    The PTC element is made out of some kind of stone and is self regulating. Its temperature and wattage drops as temperature rises. Immersion length is short, typically 17 cm for a 150 watt element so no problems getting it to fit in the sump. They typically cost around GBP 20 each.
    These come in different ratings, but the 100 to 200 Watt range is possibly ideal. Note that their immersion length increase with wattage. The one shown is the photo is made by Rica. It is IP55 but that can be improved by applying two pack epoxy. Lead can be better protected by a suitable rubber hose. I intend to run the lead to the right hand side of luggage area and just tuck its plug into the wee net basket storage space when not used.
    Best fitting position seams to be transverse from inboard, i.e. from transmission end. A 1/2" BSP boss has to be welded or brazed to the sump. Brass bosses are available from Screwfix or Toolstation. Just use a 1/2" brass straight socket or a 15 mm x 1/2 compression coupler female.

    Got a couple of photos showing the engine with sump:




    150 Watt Rica PTC immersion heater for sump. Length from seal 170 mm. (300 Watt Rica PTC immersion heater for coolant. Length from seal 250 mm. Can only be fitted in tunnel return pipe. It is too long for the sump.)

    Here we have the element fitted in my old steel sump. Boss is 304 stainless steel and came all the way from China. Only 50p with delivery. Boss is brazed to sump with silver.


    More photos:



    I will protect cable with a rubber hose and perhaps add a few turns of self amalgamating tape over exposed part of element where cable is terminated. Sump will soon receive a few coats of epoxy paint.







  • #2
    Really good idea, might be worth securing far end of heater element to prevent stress of vibration on mounting boss, although it does look quite large and sturdy. Reminds me of Volvo offerings of years gone by.

    Cheers!

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    • #3
      Heater element is housed in a stainless steel pipe. Very stiff and short so I doubt vibration will be an issue but I'll soon find out.

      Comment


      • #4
        The predominant frequencies of the engine varies from 13 to 75 Hertz. Natural frequency of oil pan heater element, I assume, will be at least in the order of ten times higher so vibration should therefore not be an issue. To play it safe I will measure the natural frequency of heater element as soon as the fresh paint has dried. Good point raised there captain and something I had overlooked.

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        • #5
          Natural frequency of the 150 Watt PTC heater is 187 Hz. It can therefore not be excited by vibrations caused by a turning engine.

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          • #6
            Vibration won't be an issue as it'll be damped by the oil. The only concern I would have is directly heating the oil over a small area. If the car is not running and the oil isn't moving, is there a chance of burning the oil which would reduce the lubricating qualities. I don't know how hot these get. Do you know of a similar thing but runs on 12v? I've been looking for a suitable windscreen washer tank heater for years.

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            • #7
              Originally posted by Evilution View Post
              Do you know of a similar thing but runs on 12v? I've been looking for a suitable windscreen washer tank heater for years.
              This is something I've thought about, I came up a diesel glow plug or two submerged in the washer reservoir, obviously they would need to be mounted in such a way that they don't melt the reservoir itself, but that wouldn't be difficult.

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              • #8
                PTC elements are self regulating. Their heat output drops as they get hotter. They can even be turned on dry with no risk of burning out element. Heat flux is 2.6 Watt per cm2. I doubt it will burn the oil. Heat flux from a 6 inch frying pan is much more typically 11 Watt per cm and we know that is high enough to burn oil.
                I'll test it out with 2.5 litres of oil before fitting. It will be interesting to see how hot the oil gets. I doubt it will go much above 90 C.

                I suggest you use a 24 volt glow plug for your washer tank. That ought to work. Glow plugs typically draw 10 A so only 5 A if you use a 24 volt glow plug in a 12 volt system. A much easier option is to weigh down a bulb and immerse in your washer tank.

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                • #9
                  Originally posted by tolsen View Post
                  Good point raised there captain and something I had overlooked.
                  You have a short memory then! `I cited this as a reason for not wanting one when you suggested one a few weeks back.

                  Just in case this has been overlooked....the element's potential to obstruct the suction pipe.

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                  • #10
                    Originally posted by Evilution View Post
                    Vibration won't be an issue as it'll be damped by the oil. The only concern I would have is directly heating the oil over a small area. If the car is not running and the oil isn't moving, is there a chance of burning the oil which would reduce the lubricating qualities..
                    If the element is designed for heating water then temp should be less than 100C to prevent localised boiling. Oil will take higher and it takes upwards of 200C IIRC (ring belt temp) to carbonise engine oils.


                    Originally posted by Evilution View Post
                    I don't know how hot these get. Do you know of a similar thing but runs on 12v? I've been looking for a suitable windscreen washer tank heater for years.
                    Can't you spur some coolant off into a copper tube immersed in the reservoir prior to it entering the radiator? Not as quick acting as electrical heater but once up to temp.If you just want hot water at the jets wrap the supply pipe around the radiator top hose a few turns - or build a small heat exchanger of the type that were marketed several years back.

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                    • #11
                      Originally posted by Thrumbleux View Post

                      You have a short memory then! `I cited this as a reason for not wanting one when you suggested one a few weeks back.

                      Just in case this has been overlooked....the element's potential to obstruct the suction pipe.
                      My brain obviously did not consider vibration being a problem. I checked for obstructions and won't even be near oil suction pipe. I also checked oil level in sump to be sure element would be submerged.

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                      • #12
                        Originally posted by tolsen View Post
                        My brain obviously did not consider vibration being a problem.
                        I'm still concerned that vibration will be problem. Lying horizontally it will experience bending loads at its mounting from the primary vibration which can be quite severe at idle. Possibly I'm being over cautious - and there isn't an obvious method to restrain its other end.

                        Originally posted by tolsen View Post
                        I checked for obstructions and won't even be near oil suction pipe.
                        Good!

                        Originally posted by tolsen View Post
                        I also checked oil level in sump to be sure element would be submerged.
                        I wonder how effective it will be heating the bulk of the oil with the oil lying stagnant around what is a somewhat localised heat source. Time will tell I guess.
                        The underlying idea is good though - prewarmed oil can only help given that the bulk of engine wear occurs within the first three minutes of cold start-up, and most of it due to the inability of the cold thick oil to circulate freely.

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                        • #13
                          The oil will naturally circulate gently around the element as currents will be created by the heat. This effect is used and maximised in the coolant circuit through the turbo to allow continued cooling after the engine is switched off.

                          Cheers!

                          Comment


                          • #14
                            Originally posted by Thrumbleux View Post

                            I'm still concerned that vibration will be problem. Lying horizontally it will experience bending loads at its mounting from the primary vibration which can be quite severe at idle. Possibly I'm being over cautious - and there isn't an obvious method to restrain its other end.
                            Check this one out:
                            http://www.ebay.co.uk/itm/Wolverine-...p2054897.l4275
                            Cummins oil pan heater 10.75 x 0.75 inch. 500 Watts. Mine is 161 x 11.1 mm. 150 Watts. By pure coincidence, mine is an exact scaled down version of Cummins'.

                            There is indeed an easy way to pin the free end simply by adding a sliding support. No need since its natural vibrating frequency is much higher than engine frequencies, hence cannot be exited, see one of the previous posts for further details.

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                            • #15
                              Originally posted by tolsen View Post
                              No need since its natural vibrating frequency is much higher than engine frequencies, hence cannot be exited, see one of the previous posts for further details.
                              Just because it doesn't join in.....doesn't mean it doesn't get a good shaking!
                              (I'm paranoid about destructive vibes. I'll tell you about the fabricated alternator bracket on a Ford Kent some day...)

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