water tanks

[sneakyalien]

I connected a Multimeter to the sensor and measured the resistance(with meter dial turned to 200(the setting before 2k) and the reading gave 00.5(when engine cold) and 00.5 when engine was hot, so there was no change in the resistance between the two connections of the sensor. Does this mean the sensor is broken?


Cheers

[MidLifeCrisis]

Yep - I'd say that it seems that your sensor is shorting ( ie no resistance)

[sneakyalien]

Yep - I'd say that it seems that your sensor is shorting ( ie no resistance)

Thanks.
Is this the replacement part I need for a C reg 1900cc T25 high top?
http://www.coolairvw.co.uk/Item/Shop_by ... e-CB-.html

cheers

[MidLifeCrisis]

Is this the replacement part I need for a C reg 1900cc T25 high top?
http://www.coolairvw.co.uk/Item/Shop_by ... e-CB-.html

I'm pretty sure that isn't the right part - that seems to be a temp 'switch' whereas you need a temp 'sensor' - I'm trying to find info on which one you need (as there are a number of different coloured option depending on engine type etc ) - what engine type do you have (DF, DG, etc etc)(assume petrol?)

[sneakyalien]

I think I have been testing the wrong sensor - I have been testing the one with two small pins that is indicated by the green arrow.
Should I have been testing the sensor that is circled in blue(This only has one wire connected to it)?
the engine in the pic is not from my camper, but looks just like my engine in terms of where everything is etc.
My engine is 1.9 Petrol.
Cheers

[MidLifeCrisis]

I think I have been testing the wrong sensor - I have been testing the one with two small pins that is indicated by the green arrow.
Should I have been testing the sensor that is circled in blue(This only has one wire connected to it)?
the engine in the pic is not from my camper, but looks just like my engine in terms of where everything is etc.
My engine is 1.9 Petrol.
Cheers

Ah - yes that one (green) is the wrong one - that is temp 'switch' that turns the manifold heater (and choke heater?) on/off - I did think early on that you might have been testing the wrong item but you said somewhere in an older post that when you'd removed the connector the gauge reacted so I assumed that you had the right one ...
... Tough to tell from that pic but yes, the sensor you want is in that general area (blue circle) - pull the connector off (it might be one or two pin connector) and ground both pins (or just the one pin if there's only one) and the gauge should go to 'full hot' - if it does then that's your sensor!!!

[sneakyalien]

Thanks for the reply.
I think something really odd is going on.
If I disconnect the cables from the two pin sensor(see pic) the temp gauge just falls to the lowest position straight away - Soon as I connect the cables back up the needle rises to the right most position.

The sensor with one connection(see pic) does nothing if I remove the cable from the connector of the sensor - I touched the metal of the van(Is this earthing it?) and nothing happened to any of the gauges.
These pictures are of the engine in my van.

twopin.JPG

1pin.JPG

147_2523.JPG

Thanks

[MidLifeCrisis]

Ok - that's progress!!
One of the two wires connected to that two pin sensor is the wire that should be connected to the one pin sensor;
Take the two wires off the two pin sensor and touch each one in turn to a bit of engine metal - the one that makes the needle go to 'hot' is the one that should be connected to the single pin sensor.
If you do that then the temp gauge should start working ....... but then obviously you have a spare wire (the yellow one that was going to the one pin sensor) and a two pin sensor with only one wire going to it ..... I would resist the urge to connect the two together as something strange has been done to your engine and it needs trouble shooting.

FYI - the two pin sensor (which is actually a temperature controlled switch) is meant to control power going to the manifold heater and the choke coil heater ...... so the switch has continuity when it's cold - to allow power to the heater elements and then it opens when it gets hold (to shut the heaters off once the engine and therefore coolant is hot) - (Haynes suggests that it does this via a relay but not sure if this is always the case .... Anyone??)

Hope that all helps

[sneakyalien]

Thanks - I disconnected the two cables from the twin pin switch and one of them made the needle rise when connected to earth, so I connected that cable to the single pin sensor and then the needle started to fall again to the left most position - Does this mean the sensor is no good?

I have left the other two wires not connected to anything.
Thanks for your help.
Cheers,
Steve

[MidLifeCrisis]

Well - that gauge is showing coolant temperature - so if the coolants hot then the gauge should show hot. Otherwise the gauge will show cold.
You'll need to run the engine for a while and see if the gauge moves??

[sneakyalien]

Thanks.
I left the engine running for about 15 minutes and the gauge started to rise, and after 15 minutes it was up to the position in the pic below.
I felt around the rubber pipes of the engine and noticed that after about 15 minutes the top pipe (indicated by the yellow line) was too hot to keep my hand on, and the pipe below it(red line) was just warm and I could keep my hand on it- Is this normal for the top pipe to get that hot?
Thanks for all your help on this.
Cheers,
Steve

[MidLifeCrisis]

If those are the pipes that I think they are - one is the pipe to the radiator and other is the pipe back from the radiator - so yes, one should be hot and the other less hot.
FYI - on most vans the gauge needle will usually sit at the 12o'clock position when the engine is at normal operating temperature (the thermostat opening/closing should keep it there) but note that some vans show the needle a little to the left or right of 12o'clock - you just need to learn the vagueries of your van - but it looks like its working now!!

[sneakyalien]

Thanks Very much for all your help with this.
I think I need to get it to a garage to get the other two cables checked because they are just dangling, now and the two pin sensor has no wires connected to it.
Will the van still run without the two pin sensor being connected...Just need to find a garage in the Lancashire area who can take a look at it.
Cheers,
Steve

[MidLifeCrisis]

Yep - it just controls the manifold heater and the choke heater - both of which help with starting so if the engine starts ok then you won't be doing any damage;
Where are you located - it's possible that there's an 8090 member in the area that could help you out for beer tokens!!

[sneakyalien]

I'm based in Preston, Lancashire.
Cheers,
Steve