Styling Water Coolant Temp Problem

[AnfielRed118]

My Marea Weekend has developed a problem that i'm struggling to understand/fix.
The temperature shown on the gauge is drastically lower than normal. It used to get to half way then the thermostat would open and it would then drop off to around 1/4. Now it gets to 1/4 then drops off to virtually zero. When left idling it gets to half way after about 30 mins but as soon as i start moving the temp drops back to near zero. I'm sure it's not the gauge/sender as it does go to the half way point as normal.
Having read certain threads on this site i've tried everything to sort the problem. I have 3 bleeds points, 2 on top of the rad and one at the bottom which are producing no signs of air. I have no bleed points on any pipes leading to the heater matrix but with the lack of constant warm air into the car itself i think there could be a build up of air in the heater matrix itself. Having taken advice i've even tried raising the front of the car and running it with the cap off with the intention of trying to get any air to come to the highest point.

Has anyone else got any other suggestions on what i can try?

I know it's cold at the moment but this has never happen before and i'm freezing driving to work at 4.30 in the morning.

:bang: :bang: :bang: :bang:

 

[bulldog5046]

sounds like the thermostat is jammed open, i'd advise replacing as soon as possible as it causes the engine to overfuel/borewash.

mine has had the same issue, while you do the thermostat order a new ECU temp sensor aswell

Ry

 

[Livefast123]

Just sorted the same issue on the Mrs Rover 25. It would get up to temp idling but as soon as I started driving it would fall to zero especially on the motorway. Took the thermostat out and found it had fallen apart ie only the metal outer ring was left...........just wondering where the other parts went!!

As said above.new stat and sender

 

[bpetersb]

The temperature gauge should not drop when the thermostat opens. The thermostat opens gradually so the gauge should show a steady rise up to normal operating temperature. I agree with the previous reply, replace the thermostat. For the extra few quid and time whilst your head is under the bonnet a new sender would be an idea also.

 

[Renegade_8]

When I did mine I just swapped the T Stat. it worked but its a fiddly job with lots of hose clamps that are a pain to reach. I think I took some intake plumbing off and I did think about removing the battery but managed without. I refilled it slowly afterwards and then bled it it and no probs.

 

[AnfielRed118]

Thanks for all the advice. Looks like i'll be changing the Thermostat then. Is this a dealer only part or are there generics available?

 

[bpetersb]

Most decent motor factors will have them

 

[AnfielRed118]

To everyone that replied to my problem a big thank you. Changed the thermostat and everything seems back to normal.
I haven't changed the temperature sensor yet as the one that's fitted seems to be different to the one that should be on the car. I say different in the fact that when i try searching for a replacement it indicates for a 1.8 it should be a 2 pin connection, but the one that's fitted is a 3 pin which appears right for a 1.6. Is this common or am i just not looking in the right places? The sensor in place is the original and the wiring hasn't been altered. Any clues or advice on where to look for a new one.

 

[bpetersb]

If it is not overheating and the temperature gauge is going up to about half way then staying there don't worry about the temperature sender, it looks like its working as it shoud.
Re the problem with different parts, welcome to the new motor trade. When I first jointed the motor trade in nineteen canteen you could ask for a set of brake pads for a cortina 1.6 or just about any other car and there would be just the one option. Now there are often half a dozen which makes it very difficult. The other day changing pads on a citroen the option that fitted was specifically shown in the catalogue as for 'non ABS' systems but the car had ABS!