DIY sump/ oil pan heater

[tolsen]

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.

[tolsen]

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.

[Kapt. Q]

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!

[tolsen]

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.