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Discussion Starter #1
Hi folks,

I finally took the plunge and changed my mondeo for a 156 2.0 JTS Veloce last week and like it a lot. I noticed that the trip computer mpg reading is very low (< 20mpg even when doing motorway @70mph) after reading lots of posts I guess that my thermostat needs replaced, especially given that the temperature never gets above 70, it gets close after about a mile or so and then sinks back to just above the 50, if it's idleing it'll climb a wee bit but as soon as you set of it comes back down again. I've read that the temp should sit around 90 but was wondering if this should still be the case in winter (2 - 3C outside)?

The cars to go back in to the garage as they are going to replace the cam belt for me so I was going to ask them to check the thermostat too, do you think that's something that a warranty would cover or even that the garage should just fix, it's from arnold clark and I have to say I was a bit surprised when they offered the cam belt change so they may just do it without a fight, am I right in thinking that the part is only about £30?

One last thing... I'm just curious but how does the thermostat affect mpg?

thanks :D
 
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Get 'em to stick a new 'stat in - the engine is inefficient when running cold - I noticed a difference when I replaced mine :thumbs:

Out of interest, what is the mileage & age of the car? <-- cambelt related
 
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Is this the first belt change?

3 years or 36k is the 'now' recommended interval :eek:
 

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hmmm, no idea, maybe that's why they are getting nervous and offered to change it?
Since you say you're 'surprised', I presume they're doing the cambelt for free? Or rather, if you've purchased a JTS from an Alfa dealership without them replacing the cambelt/tensioner/idler before sale, then they really will get themselves into trouble.:tut:

And you shouldn't be surprised anyway. Or rather, it should be clear that the cambelt/tensioner/idler must be replaced every 36,000miles/3 years (whichever occurs first) on the JTS engines. On the second belt change at 72,000 miles you must also replace the balance belt/tensioner.

Get them to replace the stat at the same time, given the age of the 156 it'll need new coolant anyway (this must be replaced every 3 years minimum, ideally every two years). If the coolant is either 'pink' or 'blue' make sure the same colour coolant is used when changing. Also make sure you get a copy of the internal invoice (if they're paying)to prove that the job has been done.

If you're paying for the belt change then you've been done......

Honestly when you hear stories like this it's no wonder the dealer network is in such a shambolic state..........
 

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One last thing... I'm just curious but how does the thermostat affect mpg?

thanks :D[/QUOTE]

thermostat is a valve that keeps engine at a efficient temperature where parameters are set for
is engine runs too cool its ineffectively like driving on choke:thumbs:
 

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One last thing... I'm just curious but how does the thermostat affect mpg?

thanks :D
thermostat is a valve that keeps engine at a efficient temperature where parameters are set for
is engine runs too cool its ineffectively like driving on choke:thumbs:[/QUOTE]

Yes the ECU will continue to think that the optimum temperature isn't reached (which it hasn't) and will contimue to throw too much fuel in the cylinders.

And this is not a good idea with the JTS engine anyway, which in the first couple of years of production suffered from severe fuelling problems (leading to coked up heads, poor mpg, and poor bhp). Many a JTS tested on the rolling road have produced sobering bhp figures such as 135 or 140bhp, rather than the 165bhp as suggested.
 

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It all points to to a defunct thermostat. You will find a huge difference to performance & economy , once it has been changed. £25 to buy it and an easy fix.
 

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I changed my 'stat a few months ago and it did make a difference in mpg, for what it's worth on a 2.5 V6 continually doing the school run!
 

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The temp gauge on my 156 JTS sits dead at 75/80, the engine idles at 800rpm and still returns a good 36mpg m/way and 32mpg town driving, and the hose from the sat to rad is cold, so i just put it down to the gauge being cool.

BTW Scott1975 get some 10W/60 oil, she’ll need it, and check/top up once a week/100miles, don’t worry their can use up to 1litre every 1000miles.
 

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Discussion Starter #14
well it was in today to get the cam belt done and thermostat checked. Apparently the mechanic ran it after the cambelt change and "it was reading 90 which is optimum for your vehicle sir" although no new thermostat. I was a bit sceptical but thought they maybe just accidentally fixed something. On the way home tonight I thought I'd do the motorway to try and heat it up, no change, guage still sits between 50 & 70 and mpg was 14mpg under acceleration (according to trip computer). I didn't ask whether they got the 90 reading from the guage or an ECU reading. But can the guage and the trip computer be that far out or is it more likely they wanted finished on a friday? I've filled the tank from (very) empty (£65:cry: - I remember filling my 1st mini for £10) and zero'd the trip counter and odomoeter to try and get some real mpg figures but I suspect I'll be back on to them very soon:rant:
 

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Discussion Starter #15
.... oh and I read somewhere about checking which hoses heat first to help diagnose a thermostat fault but cannot find it again, does anyone know what the order should be?

thanks
 

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in morning start car up and warm it up and feel top hose and if it starts warming as engine does thermostat is duff
if it stays cold and then gets warm after ten mins say just check temp gauge to see what temp its opening at
 

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Discussion Starter #17
I've started it from cold to see what happens with the hoses, I'm not sure which hoses are which so I took some pictures...

Hose A - This one gets hot straight away and trickles into the header tank all the time

Hose B - This one gets hot straight away too

Hose C - This one got hot after a while (about 10 minutes) but the temperature on the guage was still just above the 50 mark

I'm half tempted to just get a thermostat and fit it myself :rolleyes:
 

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