I have a ford KA 2006 basic model with duratec engine.

I have what I think is a weird problem. I use the car for short journeys mostly but just recently took the car for approximately a 15 mile journey. If I take the car to 50 or above the temp warning light comes on if I dip the clutch and slow the vehicle down to 30/40 miles an hour the temp light goes out.

I retook the journey keeping the car at about 40mph and completed it no problem with no temp light coming on. On the return journey I again kept to between 40/45 and no temp light. Towards the end of the journey on a dual carriageway I increased the speed to 60 mph for about half a mile and the temp light came on, I dipped the clutch and slowed and the temp light went off, I continued the journey for approximately another 2/3 miles at 30/40 mph and no temp light.

The car is not overheating to the point of boiling up, the rad fan kicks in and the heater in the car works very well. The car starts ok and has no misfiring or timing issues it is just this problem.

Can anyone throw some light on probable causes for whats happening please.

 

Thanks in advance

is your water pump not working well at speed and needs renewing 

56 minutes ago, dezwez said:

is your water pump not working well at speed and needs renewing 

Yep, it is a good point. My StreetKa had something similar, ended up with new water pump, belt and belt tensioner. 

May be worth to check thermostat housing and temp sensor? 

Hi,

Thanks for the reply. There gas been a further development LoL. I changed the temperature sensor as that is very easy and I started the vehicle up.

I left the vehicle running for 2 and a half hours and gave it a couple of very high revs. everything seemed fine, heater blowing hot, rad fan kicking in and no boiling up.

Decided to really give it a workout so I took it to the A13, soon as I got to about 55/60 the temp light came on, dipped the clutch and out it goes. Bit fed up with it all decided I would run it at 60 for a quite a  while and see what happens.

Result was suddenly the heater started to blow cold air and the temp light stayed on regardless and the car reached boiling. Now the top of the rad is cold even tho the rad fan is working, the top hose doesn't feel as hot as it should but the heater pipes supply and return are very hot.

Will these extra clues provide enough detail for a diagnosis.

 

Thanks in advance

You left it running for two and a half hours!!!

Yes, seriously I left it running outside my house for two and a half hours before taking it to th ea13 to thoroughly test it. Another development is that there is quite a lot of white smoke from exhaust and it heats up to temp light on very quickly now so I am thinking maybe the head gasket has failed.

9 hours ago, tooloud said:

Hi,

Thanks for the reply. There gas been a further development LoL. I changed the temperature sensor as that is very easy and I started the vehicle up.

I left the vehicle running for 2 and a half hours and gave it a couple of very high revs. everything seemed fine, heater blowing hot, rad fan kicking in and no boiling up.

Decided to really give it a workout so I took it to the A13, soon as I got to about 55/60 the temp light came on, dipped the clutch and out it goes. Bit fed up with it all decided I would run it at 60 for a quite a  while and see what happens.

Result was suddenly the heater started to blow cold air and the temp light stayed on regardless and the car reached boiling. Now the top of the rad is cold even tho the rad fan is working, the top hose doesn't feel as hot as it should but the heater pipes supply and return are very hot.

Will these extra clues provide enough detail for a diagnosis.

 

Thanks in advance

This is deffo a stuck thermostat and may be the housing as well. Hopefully with your experiment you didn't cook the head gasket....

It doesn't open up, so the coolant doesn't go around. Because the temperature is cold outside, you need a bigger effort to get it overheat. For starter just change the thermostat, it costs £5 from eBay. 

Thanks for the reply szabika. I am updating on this thread incase anyone else has the same sort of problem

Today I took the thermostat housing off and removed the thermostat as a way of diagnosing whats happening. Filled the water system up and started the car. In the expansion header tank there did not appear to be any circulation, the heater pies were both hot but the heater was blowing cold, the top hose to rad was cold and stayed cold for the duration and the car got hot so I turned it ff. I noticed there was a small trickle coming from the top heater hose where it joined the thermostat housing, this pipe has a adjustable hose clip on it and so I tried to tighten it up. During this process the hose connection of the housing sheared off (they are plastic). So I could not finish my testing off.

My intentions are to fit a new thermostat housing including thermostat and new temp sensor (eBay £15 ) run the vehicle and test to see if the return pipe  to the header tank gets hot and re test all the other pipes for heat,I have ordered a sniffer test to check the head gasket. Once I have re assemble the system and done my checks I will start the vehicle and do the sniffer test. all being well the head gasket will not have failed and I will then have the water pump fixed. I have spoken to various mechanics and the consensus of opinion is it has been the water pump at fault all along.

I will update this thread with the results as this may help someone else in the future.

On 1/3/2017 at 2:27 PM, dezwez said:

is your water pump not working well at speed and needs renewing 

I still go with this.  There not to bad on price 

2 hours ago, dezwez said:

I still go with this.  There not to bad on price 

Yep, could be possible... I got mine for £16 from eBay. 

But cold air from heater and cold top rad pipe indicates may be some blockage? Possible thermostat or the valve. 

Regarding the heat control valve, so many paranormal issues with it . When it get stuck closed (it means no heating) cause overheat and pressure over built in the system. I seen on different forums, KA's overheating problem was caused by the control valve. 

 

Regarding the water pump change, you need gynaecologist hands :D Also, remove the headlight , easier access. I seen horror stories on the net, where mechanics wanted to remove the block to replace it. 

2 hours ago, tooloud said:

My intentions are to fit a new thermostat housing including thermostat and new temp sensor (eBay £15 ) run the vehicle and test to see if the return pipe  to the header tank gets hot and re test all the other pipes for heat,I have ordered a sniffer test to check the head gasket. Once I have re assemble the system and done my checks I will start the vehicle and do the sniffer test. all being well the head gasket will not have failed and I will then have the water pump fixed. I have spoken to various mechanics and the consensus of opinion is it has been the water pump at fault all along.

I will update this thread with the results as this may help someone else in the future.

Do you still have the old thermostat? Throw in a cup of boiling water and you can see it opens up or not.

Any progress on this subject?