Technical Cold Start Device 8140.47

[Finkey]

Any body know where I can get one of these
Or have a genius way to replace it with an electric motor or cable up to the drivers seat?
I can't find it on ePER, Ebay, Amazon or Google.
Only reference I can find is in the Workshop Manual.

Mine has stuck in the "relaxed" or "starting" positition.
I've got it out and soaking the piston with WD40 but don't hold out much hope.
The coils ok drawing a couple of amps at 12v.

Anybody had one of these apart? Is there a bellows or a piston arrangment.
I guess being stuck on starting position wouldn't impede starting.

 

[Communicator]

The cold start device serves to advance the injection timing on a cold engine, which gives the injected fuel more time to heat up. The device uses a waxstat to restore the injection timing when the engine warms up. Heating of the waxstat can be by engine coolant, but a thermostatically controlled electric heater is easier to implement. Have you checked that the waxstat receives 12V when the engine is warming up, as the thermostat could be faulty?

For more information of on the workings of the advance device, see this Motor Roam website article.

If your engine starts and runs OK, than little to worry about.

 

[Finkey]

The cold start device serves to advance the injection timing on a cold engine, which gives the injected fuel more time to heat up. The device uses a waxstat to restore the injection timing when the engine warms up. Heating of the waxstat can be by engine coolant, but a thermostatically controlled electric heater is easier to implement. Have you checked that the waxstat receives 12V when the engine is warming up, as the thermostat could be faulty?

For more information of on the workings of the advance device, see this Motor Roam website article.

If your engine starts and runs OK, than little to worry about.

Thanks for the info.
Yes, I've seen the rather fine MotorRoam article.

It's the starting that's troublesome.
The WD40 soak and a gentle pull with the mole grips has freed it up,
Volts and amps all ok.
Tomorrow I'll see if it's wax pushes hard enough to compress the spring.

Thanks again for the up

 

[Finkey]

Any body know where I can get one of these
Or have a genius way to replace it with an electric motor or cable up to the drivers seat?
I can't find it on ePER, Ebay, Amazon or Google.
Only reference I can find is in the Workshop Manual.

Mine has stuck in the "relaxed" or "starting" positition.
I've got it out and soaking the piston with WD40 but don't hold out much hope.
The coils ok drawing a couple of amps at 12v.

Anybody had one of these apart? Is there a bellows or a piston arrangment.
I guess being stuck on starting position wouldn't impede starting.

Yippee! WD40 and a tweak with the Mole grips freed it it's now working on the bench.
Now to get it back onto the engine.

Incidently it reduces current consumption as it heats.
Starts at 1.8A and reduces to 0.8A when fully extended.

 

[Communicator]

Yippee! WD40 and a tweak with the Mole grips freed it it's now working on the bench.
Now to get it back onto the engine.

Incidently it reduces current consumption as it heats.
Starts at 1.8A and reduces to 0.8A when fully extended.

View attachment 484803
View attachment 484804View attachment 484802

A positive result, but I am inclined to wonder whether the coil includes a PTC thermistor..
Resistance is directly proportional to absolute temperature. If we adopt an ambient temperature of 290K (17C) then the change of current from 1.8A to 0.8A gives 290 x 1.8/0.8 =650K or 380C. That seems rather warm, and would apply if a PTC thermistor is not used, or is my logic flawed?

 

[lycopersicum]

I think PTCs used as heaters are typically nonlinear in resistance vs temperature.

And the linear ones are only linear over a certain range; it's not a straight line going through 0 K / 0 Ohm.

 

[Finkey]

A positive result, but I am inclined to wonder whether the coil includes a PTC thermistor..
Resistance is directly proportional to absolute temperature. If we adopt an ambient temperature of 290K (17C) then the change of current from 1.8A to 0.8A gives 290 x 1.8/0.8 =650K or 380C. That seems rather warm, and would apply if a PTC thermistor is not used, or is my logic flawed?

No idea, I was a bit surprised when it changed but thought it worth a mention in passing.

 

[Finkey]

Yippee! WD40 and a tweak with the Mole grips freed it it's now working on the bench.
Now to get it back onto the engine.

Incidently it reduces current consumption as it heats.
Starts at 1.8A and reduces to 0.8A when fully extended.

View attachment 484803
View attachment 484804View attachment 484802

I was dreading putting it back 'cos it mounts on a bracket between the two halves.
The springs are quite butch to compress whilst on my back under the van.
Then inspiration struck and I got out my one of my FIAT special tools (Mole Grips).
My other FIAT special tool is a big hammer but I didn't need that.
Before I undid the screws to separate the halves I clamped the FIAT special tool on the cable crimp
thereby stopping the spring from expanding.
All went well and I'm now back in business.

 

[Communicator]

I think PTCs used as heaters are typically nonlinear in resistance vs temperature.

And the linear ones are only linear over a certain range; it's not a straight line going through 0 K / 0 Ohm.

It was just a thought in passing, and I was making the point that if the heater was just a resistive winding, then the calculated temperature rise was rather high. I had not considered the possibility a PTC thermistor on its own. Your implied suggestion makes good sense, when the oil vapour heater on my 2.8jtd is in reality a PTC thermistor.