Dash showing engine temp is realy hot! NOW SOLVED!

fan trick is real quick and half a dozen cable tie`s max worked for the last 3 or 4 moter`s mine included same symtom`s as you described

How easy is it to change the thermostat? Any links to how to do it?

Nobby

Just want to ask have you taken the viscous fan out for any reason .
The reason is if you lie a viscous fan flat on the ground it will ruin the viscous set up.
It will have less resistance, I think a new fan can be laid flat but not a second hand one as the seals leak which is not visible. An electirc fan connected to the thermo sensor is a good set up with a manual over ride to keep it cool while doing slow tecknical stuff, plus it wont thrash around in water

Another point is your water pump could be worn out!! If so get it changed and quick..
And always ues one coolant as mixed coolants can turn too acid which eats the metal water way tubes which run from the engine block to the head which causes a premature head gasket failure.

Whilst driving with the engine hot throw on the heaters full and hot, if the airflow remains cold rather than heating up, ya may have a thermostat problem, i would defo check the thermostat !! sounds like it is not opening properly or very delayed, ive experienced "phenomenon" haha in many cars and its always been a faulty thermostat !! Best of luck with the experiments and fixes !

Thanks for the advice guys. Fearghal Murphy, i have done this and they work fine. I think "phenomenon" is a very good word to describe it
One thing i can not work out is only my daily commute to work, about a 15 min drive, the engine reaches its normal temp and stays there fine. Its only since going on some recent longer drives that the temp reading has shot up. Also the needle goes up and down as i drive along, it goes right to the top then drops to about two thirds. But as i say this only happens on longer journeys.
Jo king in answer to your question, no i have never taken it out. I didnt even kno what one was until starting this thread I always assumed it was just the fan.
Could the viscous fan be sticking? So i works for a while then sticks, the temp goes up, then releases for a bit, the temp goes down.
Any advice most welcome

Thanks again

Nobby

add an additional temp indication....... i got a bad experience with the stock one

If it was me I would not "lock" the fan up as all you are going to do is over cool the engine and just mask the problem, all of the syptoms you are saying point to a sticking thermostat. I have have not seen a fan to start and stop work it's a very simple bit of kit when they fail they normly lock up solid or just turn very slowly.

Thanks again guys
As kirkynut said if it was stuck shut the engine would overheat and stay hot, wouldnt it? Does the viscous fan only kick in when the engine starts to get to hot and so helps to cool it down? The temp reading stays fine on a short journey but only goes up and down when on a longer trip. It doesnt stay in one place if you kno what i mean.
So this cable tie trick, do i tie the viscous fan to the main fan?
I have just put fresh coolant in do you think if i drained it, to fit a new thermostat, i could re-use it? Or is it best to put new in again. Its only been in a week or so.

Nobby

To check the viscous unit:

With a cold engine, grab the fan blades and see if there is side to side play or a rattle = gone
Try and turn the fan by hand. If it feels stiff but will turn it is ok.

Most likely, the fan will feel loose and spin easily = gone.

Go for a drive with the window open. When you first drive off the fan should roar like a vacuum cleaner when you rev the engine from cold, then the noise disappears when hot.

(No idea why this happens, it is the exact opposite of what you would expect, possibly the fluid has to warm up before it can start working properly)

I may be able to help you with this Process of elimination
Ok this is what to do First you can check your thermostat by removing it from your car and putting it into a pan and then pour boiling water from a kettle on to it. If it does not do anything then Its buggered if you see it pop or move then its fine and you can put it back in The thermostat activates at around 83 degrees so boiling water will trigger it.
You may have an air lock in your cooling system.. seek advice as to how to get the air out...
Answer these questions
1 Are you losing water only slighty
2 And can you see tiny dots in your oil on your dip stick.