Hi got a tddi 2001 mondeo. Was driving the other day on the a12 and the temperature went straight to the red and 2 seconds later is went bk to normal then done it again after 6 minutes but it's fine on standstill. The fan comes on everytime. I've checked the coolent that's fine and oil and got told to check water pump that's fine radiator is fine no cold pipes Everything is how it should be. Drives spot on and the engine doesn't feel any hotter then it normally does :s

And my partner said it goes cold when in the red then comes back on after its out of the red

And my partner said it goes cold when in the red then comes back on after its out of the red

What goes cold? Is it the engine or is it the heater air output?

In any case, one of the possibilities seems to be an air lock in the system. I don't know the tddi engine and whether there are any common causes for this, but check around the system and see if there are any unusual cold points. There might be some mileage in running the car up to warm with the pressure cap loosened slightly to see if that encourages any air to 'burp' out. On some cars you need to, eg, try this with the nose pointing upwards (or downwards) to make it easier to get the air out, but, as I say, I don't know the tddi, and whether there are any particular tricks with that engine.

Yea sorry the heater goes cold

Sounds like a thermostat to me. I would also suggest you check the coolant expansion cap for any damage, even the faintest of cracks or splits can cause this.

Ok mate will do cheers

Bleed the coolant made it a bit better but still going in to the red and blowing out cold air then when in goes back to normal it's red hot again

might still be an airlock, but to be honest, if its going into the red and blowing cold air, it sounds like its a stat issue.

Yes, I'd be tempted to agree that jeebowhite's suggestion of a thermostat rather than my suggestion of an airlock is more likely, particularly now you've bled the system.

Is there just the one (water thermostat) on these, or is there an oil thermostat too?

Haven't got a clue about the oil one

Tbh is stressing my misses out big time as she's got a thing about head gaskets ever since my dads rover went. It's going in the garage at 10 so hopefully they will find the problem

Fingers crossed it's a cheap fix on the stat

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Head gasket is unlikely to blow - its very tough and the engine is protected by the ECU - if the engine overheats the ECU detects this and backs off the power - even if the coolant runs dry or the waterpump fails it still does this as the temp sensor is taken off the metal in the head, not the coolant/water

There is a main thermostat and a second small oil thermostat, which is mounted on the side of the waterpump

Changing the main thermostat is an easy home/ DIY job with only 3 bolts to remove - takes about 10-15mins

Pattern thermostats often dont fit well (allegedly) genuine ones do

I would expect the waterpump to be faulty rather than the thermostat, from the OPs clues, though i would need more information to be sure

Then went to mc d's earlier and had the heat on and was in a line for about 15 minutes and the temperature didn't even get to the halfway point like it normally Does but then after driving 5 minutes it went up to normal and the fan came on but didn't last as long as it did before I bleed the system and it didn't overheat but the fan kept coming on but I didn't take it on any a roads to see if it would go in the red. The fan never used to come on so much so I no the problem is still there :s

Then went to mc d's earlier and had the heat on and was in a line for about 15 minutes and the temperature didn't even get to the halfway point like it normally Does but then after driving 5 minutes it went up to normal and the fan came on but didn't last as long as it did before I bleed the system and it didn't overheat but the fan kept coming on but I didn't take it on any a roads to see if it would go in the red. The fan never used to come on so much so I no the problem is still there :s

TDDIs generate very little heat at tickover so its hard to say, the heater can take a lot of heat out of the engine too, ironically, overcooling the engine

The engine taking a long tome to heat up points to a faulythermostat(s) (stuck open) contradicting what was previously reported

When the weather is warm it can make a big difference

Are you using the AC?

How do you know the waterpump is "fine"? give details how you tested the system - how did you bleed it? did you change the coolant?

Yea changed coolent and flushed it through a couple of time it did dribble out then rushed out after a couple of minutes. The garage said the water pump looked fine. Used a/c Sunday wasent that cold tbh but last Thursday the a/c was !Removed! cold. Lol

Got told 99% water pump

nice little bill to accompany it?

In which case I suspect you might find its worth doing the timing belt if its not already new, as they need to remove that anyway you might as well have it done!

112 for new water pump and thermostat and fitted

not too bad if its all in!

Yea tbh can't wait for it to be done doing my head in

Just a update...Water pump was knacked so got new one from ford and thermostat new coolent and engine flush and labour all for £120...not bad just hope she behaves herself from now on...

Not a bad result at all! I just wish my timing belt was as cheap as that!

nice little bill to accompany it?

In which case I suspect you might find its worth doing the timing belt if its not already new, as they need to remove that anyway you might as well have it done!

Its a timing chain on the mk3 Mondeo 2.0 -should not need replaced - can last the lifetime of the engine, waterpump is driven through the power steering pump, via a short belt off the cam, belt is cheap and easy to replace - its about £60 for a pattern waterpump and £15 for a belt last time i looked