What's this

[hal7600]

Any ideas what this does, and what part I ought to ask for as a replacement?

 

[malcolm]

Ask for an engine temperature sensor (rubbish version) for switching on the red light on the instrument panel when it is too late.

 

[Azazello]

Do they exist for different temperatures? To make the light turn on at the right time...

 

[jonigel]

No they are always to late!

 

[malcolm]

It's the location of the sensor that I don't like. Later waterpumps have a tapping for a sensor that directly measure water temperature. It's the water temperature that is important as the head gasket can fail if the water boils.

The sensor at the back of the block does not directly measure water temperature. It is influenced a lot by exhaust temperature which can change if the mixture is wrong. It'll probably switch after the water has boiled from the block. It is better than nothing, but can't be relied upon to switch on at the right time.

 

[iMacThere4iAm]

Hi Malcolm, any chance you could post a photo showing which tapping on the pump is useful for a temperature sensor? My pump has many different plugs and holes and I can't work it out.

Edit: Think I got it. I just found some photos of a nicely colour-coded engine that was on display at Thenay, with what appears to be a temperature sensor fitted (the green arrow).

The second photo is my pump, with the same port marked and another, smaller one that I don't know about.

 

[malcolm]

The one with the green arrow on your engine is the temperature sender. The other blanking plug is for pipes to a heated carburettor manifold (R5).

Not all R4 water pumps will have the tapping for the water sensor. MK1 Renault 5 pumps should have them.

 

[iMacThere4iAm]

Do you happen to remember the thread size of that tapping? I'd measure it myself but the car's still at the mechanics.
I'm guessing it'll be either M14 or M18.

 

[angel]

It's M18x150.

 

[iMacThere4iAm]

Thanks Angel

 

[elch101]

There are two different kind of sensors by renault. Those to operate a warnlight (same used on 800/B1B engines) and those to operate a water temp gauge. The gauge sensor will cause a flickering light every time the water gets a little bit warm, if used with a warn light.