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Jan 21, 2013 22:12:17 GMT
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Ok its a bit modern new shape Ford Maverick 3.0 V6 but i'm not used to this recent stuff. Had it about a week - it runs cool, but when stopped at lights the temperature gauge literally flys up before your eyes to normal - doesn't appear to go beyond this. Putting on air con (rad fans run all the time) means it drops back to cold at aprox the same speed. As soon as you are moving again it will drop reasonably quickly back to just off cold.
Doesn't appear to loose any coolant, there is a bit of mayo under the filler cap but I put this down to a fair bit of stop start.
Does an over sensitive coolant sensor seem possible? I can't imagine if the rad was that blocked it would fall so quickly once the fans are on? Haven't heard the fans kick in apart from me playing with the aircon....
I could do with ideas please. Paranoia leads to me driving with one eye on the temperature gauge!
Thanks
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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Jan 21, 2013 22:24:39 GMT
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Thermostat could be sticking or opening too early?
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Jan 21, 2013 22:31:57 GMT
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I did think of that but surely if it was sticking it would be up to temperature when running?
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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Jan 21, 2013 22:39:38 GMT
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Just a theory but some modern stuff has it's gauges set to read bang on central when the temperature's anywhere within a range around the correct temp, eg. anything from 70-90deg will read centrally on the gauge. (Pretty sure this is the case on a fair few Audis).
In theory, if this is the case, and your engine was for some reason always running a little cold, but just on the boundary of when the gauge defaults to being central, then I could see how it could move around quickly. In reality the engine might only be changing temperature between say, 68 and 72 deg, but if when it hits 70 the gauge jumps to central it could look how you describe. Long shot I know, but it's possible. Either way it'd point towards something making the engine run a bit cool, and my first port of call would be replacing the stat.
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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Jan 21, 2013 22:41:46 GMT
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Usually if the thermostat opens too early, the engine will be cooled by any airflow through the rad, from driving or with air con on, then when stationary will rise because there is no airflow through the rad, until it triggers the fan to come on which regulates the temperature nearer to where it should be.
Some modern cars seem to have temp gauges which are very sensitive over a narrow range, so when the temperature fluctuates over that range, the needle goes up and down very noticeably.
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fred
Posted a lot
WTF has happened to all the Vennies?
Posts: 2,957
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Jan 21, 2013 23:00:32 GMT
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Not having much modern so I don't have much experience
BUT... My old dear has a newish motor (2 years old)
and it happens with that
seems the gauge is uber sensitive
never goes above normal
but can flick from cold to norm in seconds at the lights or in traffic
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'79 Cossie ran Cortina - Sold
2000 Fozzer 2.0 turbo snow beast
'85 Opel Manta GSI - Sold
03 A class Mercedes
Looking for a FD Ventora - Anyone?
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GavinJ
Club Retro Rides Member
MGB 3.9 v8 Sebring
Posts: 927 
Club RR Member Number: 209
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Jan 22, 2013 11:48:55 GMT
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My daily a newish clio, was doing exactly as you described and I changed the stat and and its been perfect since.
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Jan 22, 2013 13:48:12 GMT
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Probably find that the stat isn't quite closing, so that when the radiator is very effective due to all the air flowing through it the engine cools down a lot - but when there's no airflow the thermostat still controls the temperature by opening further.
Protip: If you can't get an OE 'stat from the manufacturer, but one that's branded Calorstat, MotoRad, or Whale. Avoid QH and any unbranded tat.
You'll pay a couple of quid extra for a branded one but they work so much better it's untrue - when I rebuilt my Imp engine I put a new (unbranded) 88 degree stat in and it took ages to warm up and the heater was always a bit naff. The temp varied quite a bit as the speed varied as well. With a MotoRad one it heats up about twice as fast, reaches a slightly higher temperature (about as high as it ever got before), and the needle doesn't move between pottering in town or blasting up the motorway at 80.
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ChasR
RR Helper
motivation
Posts: 10,194
Club RR Member Number: 170
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Jan 23, 2013 11:49:53 GMT
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If it is the Duratec V6 engine it will almost definitely be the thermostat. The earlier Ford thermostat had the bleed holes in the thermostat blanked off with rubber bungs, and over the course of time these disintegrate.
I previously had near enough the same problem with my Mondeo V6 (the predecessor to the one I have one). In the end the car barely got off the white portion during the winter months despite as Robin JI stated, it having a 'damped' gauge which tended to hang around the middle. It would warm up in town if you sat for a while in traffic, but Jesus that heater was near useless on a run.
I echo jrevillug's comments regarding going for the best thermostat you can afford. In the Mondeo the thermostat was not far off £30 IIRC. But it warmed up very quickly in addition to the car averaging 24MPG in town without driving like Missy Daisy (not bad when you consider the car was a 2.5 V6 slushmatic weighing 1600kg). The Stag had an OE (ish) thermostat supplied by a well known Stag supplier (the motor factors tried to sell me a MkI stat, not great when it does not have the foot for the bypass hose (and people wonder why Stags overheat...)). Again, like the Mondeo it had a warm heater within minutes of startup in addition to holding a relatively stable temperature.
On the Spitfire I bought I decided to put in a cheaper thermostat to see if there was any difference. Sure enough, there was. It barely warmed up even during the heigh of the summer, and the fuel economy was not miles away from the Stag (OK, the Stag has a more efficient head design, but it is still almost twice of the weight, and twice the CC of the Spitfire (1500cc vs. 3000cc)).
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Last Edit: Jan 23, 2013 11:52:11 GMT by ChasR
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