Technical temperature gauge issue

[Dreddfan]

I was driving the wifes 99 1.2 brava home on the Motorway the other night when I noticed the temp needle spiked up to max temp for a few seconds then back down to normal running temp (about half way on the scale)
It did this about three times in as many minutes then behaved itself for the rest of the trip.
Has anyone else ever had this problem?
I'm thinking that the temp sensor might be on the way out??

I dont drive this car all that much but she has said it's been a little hard to start from cold recently so a new battery is going into it when we get a bit of cash.

 

[Ziggy122]

I was driving the wifes 99 1.2 brava home on the Motorway the other night when I noticed the temp needle spiked up to max temp for a few seconds then back down to normal running temp (about half way on the scale)
It did this about three times in as many minutes then behaved itself for the rest of the trip.
Has anyone else ever had this problem?
I'm thinking that the temp sensor might be on the way out??

I dont drive this car all that much but she has said it's been a little hard to start from cold recently so a new battery is going into it when we get a bit of cash.

Air is alot easier heated then water/coolant

So it could be forwell air brushing past the sensor and giving the spike in temerpature

So make sure the coolant level is upto max - and there is no air in the system

Check the temperature sensors connector is clean and tight as well - could forwell be a dodgey connection makes it spike

And poor starting could be a weak battery - so its an ideal time for winter to clean all your earthing points

Ziggy

 

[Dreddfan]

Thanks for that,
how many earthing points should I be looking for apart from the big one under the bonnet?
Also, where is the sensor located? I have to change the same sensor on my A4 this week so i might as well do them both at the same time

 

[Dreddfan]

I've to replace the battery in the car this week (dead after repeated chargings so must be f****d )
I noticed that as well as the main earth point on the car there seems to be one connected directly from the - terminal to the body just under the battery. Someone has replaced this but there seems to be a bit of an original clip under the screw (it's the same colour as the bodywork) is this normal?
Also, there is no radio in the car at present but could loss of battery power for prolonged periods cause any other problems?

 

[bluejohn125]

Regardless of any possible electrical issues, take the opportunity to give the whole cooling system a proper service and overhaul. It becomes neglected and critical on these cars, and can cause head gasket failures.

Drain the old coolant, give the system a series of flushes and refills with water (running engine up to temperature), then maybe a rad flush compound, replace the (cheap) thermostat, and carefully refill the system with a new, decent antifreeze mixture.

There are plenty of threads on this if you look.

 

[Dreddfan]

I finally remembered to post a result to this problem thread
I went to change the thermostat and renew the coolant as Bluejohn suggested and I found that the coolant system had feck all coolant in it even though the expansion tank was up to the max mark. must have been a blockage somewhere
The main pipe going into the engine near the thermostat was leaking a bit and the whole front of the engine block was stained red from old evaporated coolant.
After replacing the thermostat ( E15 from motor factors) doing a few water flushes and refilling with proper coolant the problem is gone and the cabin heating is working perfectly.
Thanks for all the help and advice and I would recommend anyone to do the job as it only takes about an hour and a half (inc tea break )

 

[bluejohn125]

Sounds like you've been very lucky, well done for sorting it out.

It's nice to know that your cooling system is well maintained and working properly, gives confidence to enjoy the engine!