A few questions about my 2.5 V6! - V6 'Duratec' Petrol Engines (Mondeo Mk3) - TalkFord.com

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A few questions about my 2.5 V6!

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2 replies to this topic

#1 mrdoofa


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  • Vehicle Driven:Mk2 Mondeo Ghia X V6
  • Name:Martin
  • Location:Yorkshire

Posted 15 July 2020 - 02:19 AM


Hello everybody,

I have a 2.5 V6 Mondeo and want to run a few things by you guys in the know.


First of all, if I am sat in traffic the temp gauge can get uncomfortably high, the needle gets up to around the letter A in the word “Normal” on the gauge, the cooling fan then kicks in which seems to keep it from going higher, once you start moving again it soon goes back to half way. I’m getting plenty of heat from the heater, my obvious concern is the water pump which I believe is a common issue with these.


Second, when I turn the AC on I feel and hear the compressor kick in and I get plenty nice chilled air, the problem is that it makes the car run a bit lumpy and with a little hesitation, it idles fine it’s when driving you feel it. I know that AC can zap some power from the engine but I didn’t think it would be this pronounced with a V6.

Finally, (phew!!!), The IMRC seems to be working as it should as I feel and hear a change at around 3,500rpm but just wondered how you actually check it’s definitely working as it should.


Sorry for such a long post and I thank everybody for any help/advice you can give.

  • Macmondy3L likes this

Speed has never killed anybody. Suddenly becoming stationary, that’s what gets you.

#2 ancienttyres


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  • Vehicle Driven:mondeo mk3 v6 petrol

Posted 15 August 2020 - 08:14 PM

The temperature gauge shouldn't really ever go beyond half way. Mine always stays ever so slightly below half way in fact even on very hot days. It could be the water pump, but it could be other things too; lower coolant level, or more likely a sludge build up in the system (or just an outright blockage in the radiator), or the temperature sensor might be on the way out and is reading higher than it actually is (not unheard of). Could also be the drive belt is loose and not running the pump as efficiently as it should be. There are coolant system cleaners you can put in that might help clean up blockages or thin out sludge but I can't vouch for any as I've never tried them. You could perhaps try one of them first, find one that's well rated and see if it improves the cooling at all. If not then look at the pump and the belt or the sensor.

AC does indeed put strain on the engine, especially if it's the compressor is getting on a bit and becoming harder for the engine to turn over. I believe when the AC causes rough running, and in particular rough idling it can potentially be rectified by resetting the car's PCM. It's easily done, you disconnect the battery and leave it disconnected for about 10-20 minutes. The PCM then "forgets" its settings and will relearn them upon the next running. The normal way to have it relearn is to start the engine and let it run at idle until it's up to temperature (it may stall a few times but will eventually even itself out). When it's at normal temp, you rev it to about 1200 for two minutes then turn the AC on and take it out for a drive in varied conditions (normal roads and ideally a long stretch of mortorway) using your own driving style (don't deliberately thrash it or drive more carefully than you normally do as that will defeat the purpose). After half an hour to an hour or so of driving it should relearn its optimum ranges, including the added power it needs to keep the engine running smooth with AC on.


Only way I can think of to check the IMRC is working properly is to inspect the guts of the thing first hand while revving the engine. It's under the plastic cover at the front of the engine bay. You can take the top off it without disturbing it too badly. Then check to see if the gears inside operate when you rev the engine (here's a video of it in action: ). There's another couple of threads on the first page of this forum dealing with the IMRC and jamming the secondaries open which you might want to have a look at too.

#3 Steve_v6


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  • Vehicle Driven:Mk3 Mondeo 2.5L V6
  • Name:Steve

Posted 03 September 2020 - 09:06 PM

My V6 sits at half way on the temp gauge and never moves from it no matter if im driving of sitting still and no matter the season.


Its normal running temp floats between 86c and 88c and the fan cuts in at 89 or 90c if i remember right.


As for the imrc, revving the engine and seeing the valve operating does not mean that the imrc isnt faulty.


My imrc is moody and will appear to work just fine when revving up on the spot and watching for it moving but when ringing the cars neck, it can stutter and often looses the power completely, i also have a imrc stuck closed DTC code.


Its heat that causes the intermittent problem that often only shows itself when your ragging it and its also the cause of them going bad in general.

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