DIY sump/ oil pan heater

[tolsen]

More complications. Front panels must come off to run wiring and fit washer heater. The problem is the ambient temperature. Minus 5 C at the moment and my Smart is totally iced over. Risk cracking brittle front panels so this job will have to wait. Intend therefore to fit on the Trekka first. Although made by Renault, access to the washer system on the Trekka is remarkably good.

Some info that may interest Mottofree:

On my Smart 450 Cdi I have had the 150 Watt oil pan heater plugged in for 3 hours. Ambient temperature has remained constant at - 5 C. Surface temperature at top of engine - 3 C. Temperature at bottom external surface of oil pan + 10 C. Did not measure oil temperature as I wish my gauge to remain clean and not be soaked in black diesel engine oil. Surface temperature measured with a Fluke 62 IR thermometer.

[tolsen]

Washer fluid heater is now ready for commissioning and testing.


Intend to wire heater such that it turns on when washer pump is operated. This simplifies wiring as only fuse, relay, cable and crimp terminals are required. No drilling of holes in dash for switches.

[tolsen]

Used no gasket or sealant. All metal seals used throughout. Tested heater with water. No leaks and water gets piping hot. May need manual push and hold switch to control heater and run washer pump in short bursts.

[mottofreee]

Energizing the heater simultaneously with the pump is inefficient, the windscreen will only get cold liquid.
The pump must be delayed due to thermal inertia.
The spark plug must be kept warm if an immediate effect is desired.
It resolves with a little automation:
- energize the spark plug by a resetable monostable (LM555?)
- when the liquid has reached a predetermined temperature, a thermocontact is authorized to energize the wiper motor, the pump and reset the monostable.
By actuating the wiper lever, the heating timer starts and the thermocontact stops the timing and authorizes the SAM for the wiper and pump.
The thermal contact is active when the liquid reaches a certain temperature.

[tolsen]

Thinking of sourcing an adjustable delay relay. Set it up to switch on washer heater for a preset time each time washer pump is run. I can then run windshield washer in short bursts and get piping hot water without any additional switch that may distract the driver.

[mottofreee]

The function performed by the monostable here is the delay relay.

[tolsen]

We have now ordered a couple of China timer switches.
https://m.ebay.co.uk/itm/1x-DC-12V-S...pid=2215573074

Will need to use additional 30 amp relay to take the 20 amp current drawn by glow plug washer water heater. May also have to operate heater manually for some time.

[Thrumbleux]

MOT?
Can't see the tester waiting for wash and wiper to function when it is expected to respond immediately to switching - itself a safety priority should your screen without warning become deluged with some opaque gunge thrown at it.

[tolsen]

MOT?
Can't see the tester waiting for wash and wiper to function when it is expected to respond immediately to switching - itself a safety priority should your screen without warning become deluged with some opaque gunge thrown at it.

The thing is we have worked out a rather elegant solution:

Wash wipe system will work exactly as it was. Timer is for washer water heater. To get hot water out of nozzles all I do is run wash wipe for a fraction of a second which then turns on heater for the preset time possibly around 20 seconds. After 20 seconds run wash wipe again and there should be piping hot water out of nozzles.

[Thrumbleux]

So long as there is an immediate response ie wash and wipe on command, then MOT tester will be happy.

[mottofreee]

That module is not properly equipped.
Contains NE 555 where operation is guaranteed for positive temperatures (... + degrees C). The windscreen fluid should be warm when it is cold (... - degrees C).
http://www.ti.com/lit/ds/symlink/ne555.pdf
- TA parameter, page 4 bottom-

It is possible to create unpleasant surprises in operation, however it should be supervised not to fire the car.

[tolsen]

I’ll test both timer relays in the freezer at minus 25 C or lower so will soon learn if they are worth their salt.

[mottofreee]

The idea of the freezer is brilliant; Unfortunately not reproduce vibrations - in any case is a key test.
It's not an insurmountable problem.
Replace NE555 with SE555. http://uk.farnell.com/texas-instrume...oic/dp/1651887 / https://www.mouser.co.uk/productdeta...XlG%2Fp9pC0%3D
Anticorrosive printed circuit board (PCB) is also needed.
There are other provisions of automotive standards - they are not relevant in this case.
The connection wires are AWG13 multifilament, the use of wires for audio speakers. For these purposes, I use the power cord from unusable / old / non-repairable appliances. The electrical classification of the cable is MyyM x * yz (x = number of electric conductors, yz = cross section of a conductor in mmp); so MyyM 2 x 2.5 mmp in length of 2 m is enough.

[tolsen]

An elegant fixing bracket:



Polished stainless steel hose clamp size 0 to hold heater to 316 stainless steel bracket made out of 1.5 mm thick plate. Will be clamped on to existing chassis bracket with M8 A2 stainless bolt, washers and nylock nut.

[mottofreee]

Simple and effective.
This gripping system is also the solution for the filter.

[tolsen]

Washer fluid heater is now ready for commissioning and testing.


Intend to wire heater such that it turns on when washer pump is operated. This simplifies wiring as only fuse, relay, cable and crimp terminals are required. No drilling of holes in dash for switches.

Got it wired as above pending receipt of timer switches from China. Heater works well. Washer fluid is warm enough to remove dew formed on cabin side of windscreen. Have not tested heater with iced up windscreen as presently too warm.