I noticed that the temperature gauge on a friends Zafira has a very slow reaction time. However, I don?t want to check Thermostat operation unless the situation is abnormal.
Can any 2.0 Litre Diesel users comment on the following experience?
CASE 1 - Outside temperature around 0 degrees, steady urban driving conditions, initially with full hot air blow to clear frost.
a) First temperature gauge movement noticed after 6 miles.
b) Normal temperature reading (88 degrees on the gauge) after 12 miles.
c) Full blast heating alone knocked the gauge reading down to about 70 degrees at a steady 40MPH. (just registering on the guage).
CASE 2 - - Outside temperature around 9 degrees, steady urban driving conditions, no fan required.
a) First temperature gauge movement noticed after 3 miles.
b) Normal temperature reading (88 degrees on the gauge) after 6 miles.
n.b. On my old fashioned Peugeot 405, the thermostat opening is visibly noticeable on the gauge, but this has never been the case on the Zafira.
Comments welcome.
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On my Vectra which has the 2.0DTi engine this is also slow to register on the temperature gauge. I think the readings you give are about the same as I see. About five miles before it reaches its normal position which is similar.. This has been the same since new.
However I think a better indicator of the thermostat is how quickly the heater is giving out warm/hot air and on the vectra this is in a very short time.
The temperature gauge is quick to note when the engine is working hard and on a steep hill or quick acceleration it rises visibly.
I will note tomorrow how long and exactly the temperature.
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If full heater knocks the temp back to 40C, then I think we can be pretty sure the thermostat is goosed. You need to check it by starting from cold and feeling the radiator top hose as the engine warms up - it should say cold until the thermostat housing is too hot to touch then suddenly get hot as the stat opens.
RichardW
Is it illogical? It must be Citroen....
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Erm....hate to pull you up on this RichardW but Jack said the temp got knocked back TO *70DegC* AT *40mph* when the fan was on!
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Thanks for the advice. My feeling is that all is OK (I believe it has been the same since new) and the drop in temperature with fan on full blast, max temp and all vents open does a pretty good cooling job on the engine. However, I will carry out the hose temp check anyway.
Cheers
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I\'d have to disagree - consider the size of your radiator against the size of your heater matrix.
If the manufacturer puts in a radiator this size to cool your engine, I\'d be concerned if a puny little heater matrix with a fan does a better job.
I agree - I believe the thermostat isn\'t shutting.
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Jack,
I\'m with Malcolm and Richard W on this. Most modern cars stay within a couple of degrees of the normal running temperature winter and summer. The car is far too slow to warm up, and no way should it drop back to 70C even with the heater on. Using the heater shouldn\'t have such a marked effect - its capacity is far less than the main radiator. The thermostat is surely staying open.
Regards
John S
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Checked mine today Jack. Outside temperature 11c. Heater warm after half a mile.
Reached its normal running temperature of 88c after 6 miles.
Did not check if the heater pulled it down as the wife was already complaining that it was too hot.
Very similar to what you describe in CASE 2.
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Well..... I checked the top hose temperature last night and this leads me to believe that the thermostst is indeed stuck in the open position. The hose warmed up gradually along with the thermostat housing. This leads to another question. As this has most likely been the case since new (30,000 miles ago), what effect, if any, might this have had on the engine?
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I may well be derided for this opinion, but its seems to me there is nothing wrong with this car, and you are trying to find problems where none exist.
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Alvin, good to here you have a hot wife, now back to the temp. Concern here about the 40 degrees, the stat should have closed and maintained your engine at a nominal 85 90 degrees. You would not be the first owner to but a new car that had not got a stat fitted. Does the temp actually settle at the 88 figure under normal conditions an stay there. If so then it is probable ok and you should considera radiator blind ( bottom third ) in the winter. 12 miles to reach 88 is not exactly a stable tep for the engine wear characteristics. Regards Peter
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perfectly normal behaviour for a diesel. the only unusual thing here is the drop when the heater is on.
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Renault Family - How do you explain the upper radiator hose temp gradually increasing in temp when started from cold, with no noticeable gradient as a sign of thermostat opening?
Another general question for Zafira owners. Is the thermostat opening point visible on the temp gague. i.e. Does the gauge rise gradually and then reduce by a few degrees when the thermostat opens? This was certainly the case on my Peugeot 405.
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You asked for opinions, and mine is you are trying to fix a non existent problem. Based upon my experience of 2 diesels and two petrols in the last 12 years all this seems to be normal diesel behaviour. They do take considerably longer to warm up than petrols. My laguna diesel upper hose does not exhibit a "noticeble gradient" either. I assume you kept your hand on there for the full 20 minutes a diesel takes to go from cold to hot at idle?
None of my last 4 cars have ever exhibited a dip in the temperature guage to indicate thermostat opening. is your 405 a petrol? trying to compare a petrol 405 to a diesel vauxhall is oranges and apples.
As this is an opinion, I could well be wrong.
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Agreed that diesels take longer to warm up due to their superior efficiency, however this doesn't explain the significant effect that running the heater at full blast has.
I've never noticed the temp gauge drop on any car I've owned whilst running the heater at full blast - I have replaced a few thermostats in my time though.
Reconsider?
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Well, after convincing myself that there must be a problem, I changed the thermostat. Result......no noticeable change in performance! With an outside temp of 0 deg this morning the gauge didn't register at all after 7 miles. However, the heater provided warm air relatively quickly.
It seems that the diesel engine just takes a fair while to warm up. However, I am still surprised that the temp gauge takes so long to register. It seems to work normally when full temp is eventually reached.
Anyway, thanks for the advice and full marks to the guy who suggested that situation was normal! The difference in temp gauge, and hose temp change characteristics when compared to a Renault Clio 1.9D had conviced me otherwise; to no avail.
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