Technical Two sensors on thermostat housing, Uno T Mk1

[Luckor]

Hi, currently working on my Uno Turbo-conversion of my X1/9. The cable harness is in focus for the moment.

I see there are two sensors on the Uno thermostat housing, one of them I know is the temperature sensor for the fuel injection, as expected. But the other one? I have a wiring diagram from a Haynes manual showing that there seems to be some kind of injector cooling fan in the system. Could it be that the second sensor is for regulating this fan?

And while at it, do I really need a fan like this? My donator Uno certainly didn't need one since there was no sign of one in a fully functioning car.

Thanks

 

[alexGS]

I don't know what a second thermostat sender would be for - I would have said temperature gauge, but that sender's on the cylinder head. As you have a Swedish flag, and I think the Uno Turbo had a catalytic converter for the Swedish Market, I suspect the second sensor would be related to emission controls?

However, I do know that the injector cooling fan has its own thermostatic switch fastened to the plastic ductwork. That switch is either calibrated really high (hot), or usually faulty - it's very rare for the fan to come on. Most people - myself included - remove the fan and the ducting to de-clutter the engine bay. It must have been put there for a reason, but there really doesn't seem to be a problem without it, even in hot conditions. Of course, with a less cluttered engine bay and soundproofing blanket removed from under the bonnet, temperatures are probably lower than original anyway. Also, I prefer having the injectors on-view - easier to notice any leaks...

In an X1/9 I think you would get good results by opening out the side panel ducts and reducing the rain shield coverage on the engine lid, to get more airflow through the engine compartment.

-Alex

 

[SteveNZ]

I ran my Uno turbo with the injector fan installed for a while when I first got it. I did notice it turn on one day after I turned the engine off on a hot day.

The fan is there to prevent heat from soaking into the fuel system. If the fuel boils it will be hard to start.

I have only ever seen one sender in the thermostat.

 

[Luckor]

Thanks for your answers.

Alex, you're right about the car being sold as new in Sweden. Back then (1987) we had more strict emission control laws here than most parts of the world, so the car was equipped with a catalytic converter from the start but the Uno had no lambda sensor until 1988.

Nevertheless the second sender perhaps has something to do with the emisson control as you suggest. Probably I'll split the isolation of the cable harness so that I can follow the two cables. The colours of them don't seem to make me much wiser.

The reason why I'm asking this is that I'm about to drill new hole(s) in the X1/9:s thermostat housing in order to fit the sensor(s) there. The threads on these senders are not the most common on the market, so to speak...

 

[biggaitch]

talking about the injector fan, my 85 standard car turns that fan on and off for five minutes sometimes after parking..not even in hot weather, and like you guys, think it was put there for a reason...so will probably leave it! like to unclutter the engine bay, but the more I read about the development of the turbo, the more I realise what a special little car that was!! and the engineers did a fantastic job, and spent ...loads of Fiat money..when someone came to pay for his new car, the dealer said to him....you are not buying a car, you are buying an engine!!