Do modern cars have thermostates?

Hi All

As the title says do modern cars have traditional thermostats or is it
looked after by the computer? My Meriva temperature gauge is going up and
down. Until recently it was fixed at approx 90degC going up only on supper
hot days sitting in traffic. Now it sits below 80degC when cruising along
and creeps up in traffic to 90 and beyond. at approx 100 the fan comes on
and it seem to stabilise coming right down to <80 as soon as you get moving
again. With this I expect it will over heat when the summer comes. I have
had a look around under the bonnet and can't see a traditional thermostat
housing. I expect If there is one I am looking in the wrong place any hints.

Also and it may be connected the light of a car with a spanner through it
lights up after a few mins running could this be the computer telling me it
the engine is not as hot as it would like?


Pete

 

Yes, pretty much all modern cars still have thermostats, some of them
are electronically actuated via the ECU, rather than the old wax
canister style. No idea if the Meriva is old style or new style. FWIW
most modern Vauxhalls do seem to be overcooled to me, my wife's Zafira
sits at 80C unless its working really hard - these days the engine
temeprature guage is probably driven by the ECU, so need not bear any
resemblance to the actual engine temperature.

In terms of the spanner, it could be anything, you need to get the
codes read. Any vaguely competent auto electrician should be able to
do that for 30 - 40 quid, a VX dealer will almost certainly want
upwards of 60 quid for the 5 minutes required to plug in laptop and
read codes.

 

On another tack, I have a 2006 Zafira 1.6 petrol that doesn't have a
temperature gauge or any indicator that I can see. I presume if my engine
gets too hot I would be notified by a light etc. in the dashboard area.

Cheers

John

 

I hear what you say, The engine seems to get hot even when it is showing
"cold" i.e. the Heater works, I think I will have to get the codes read.

Pete

 

Cold while cruising would suggest the thermostat is stuck open while
hot while stationary would suggest the opposite. Is there water in
it?! One of my cars would run hot then spew the water out then run
"cold" as the water stopped making contact with the sensor.

Sounds like you might have a sensor problem if the "check engine"
light is coming on.

 

You can buy a code reader off eBay e.g.

http://snipurl.com/obd2cheap

 

They do,
I have a New model vectra. Just recently it would take ages to get hot ( on
the temp guage) and then drop to cold when driving. A new thermostat cured
it. Mine was probably stuck open, yours maybe the other way?

B

 

As it shows in the owner's handbook page 37 there is a warning symbol
on dash for when it is getting too hot.

 

Hi All

Thanks for the replies,

Codes read yesterday - dealer said it was Temperature control Resistor at
fault.
Non in stock - ordered overnight
Fitted today, Problem still there!

Further investigation is "possible ECU failure" £569

with no confidence this is the final solution check.

Called it a day I will put up with the warning light

Cost to me 90 smackeroos only difference warning light now on 100% of time!

Looks like time to chop car in for another

Pete

 

In general ECUs are pretty reliable in my (limited) experience,
however Vauxhall decided it would be a great idea to bolt the ECU onto
the side of the engine, so it gets cycled at extremes of temeprature
and fails :-(((. What a dumb ass idea. I'm not sure if this applies to
the Meriva or not, certailnly many VX 1.8 engines are like this.

When I wanted to check the coolant temeorature sensor out on my old
Omega I actually disconnected the ECU and checked the resistance at
the end of the loom where it connects to the ECU, to make sure the
cabling was OK, as well as the sensor itself.

As a last resort there are ECU remanufacturing companies around, bba
reman. for example.

http://www.bba-reman.com/catalogue/Index.aspx?category=29

 

Thinking about your symptoms a bit more, I would expect a dodgy
coolant temperature sensor to cause problems when starting, rather
than running. I don't think this sensor plays much of a part in the
running of the engine once it is up to temperature. The action of the
cooling fan is driven from a sensor in the rad; at least on all the
VXs I've owned, admittedly all 2000 or earlier cars i.e. X series
engines not Z. Maybe on the Meriva they use one sensor for both
functions, hopefully someone here knows for sure?

There are VX forums around where it might be worth asking about your
problems, for example I use this one a bit:-

http://www.cavweb-forums.co.uk/

Alternatively this is a good forum for technical questions on all
makes:-

http://www.honestjohn.co.uk/forum/threads.htm?f=4

 

Hi

I my all be it limited experience ECUs don't give much trouble they either
work or not. it is unlikely that just the temp sensor would be faulty with
nothing else even playing up. For the record the sensor changed was
V0093175501.

I have looked at the web page for recon ECU and £166 sounds better than £569
MD fitted.

The more I think about it I believe it is not the sensor but the actual
thermostat that controls the water. I am just not sure where to look for it
the "top hose" disappears behind the cam belt cover with no obvious bump
where a thermostat might be. I think the engine is the same as a old shape
Astra so I might pop down the library and have a gander at a Haines manual
to see if this is any help. trouble is I run a Newish car for the one reason
I thought my climbing under car days were over!

Pete

In general ECUs are pretty reliable in my (limited) experience,
however Vauxhall decided it would be a great idea to bolt the ECU onto
the side of the engine, so it gets cycled at extremes of temeprature
and fails :-(((. What a dumb ass idea. I'm not sure if this applies to
the Meriva or not, certailnly many VX 1.8 engines are like this.

When I wanted to check the coolant temeorature sensor out on my old
Omega I actually disconnected the ECU and checked the resistance at
the end of the loom where it connects to the ECU, to make sure the
cabling was OK, as well as the sensor itself.

As a last resort there are ECU remanufacturing companies around, bba
reman. for example.

http://www.bba-reman.com/catalogue/Index.aspx?category=29

 

What year / engine is it? I do have a set of VX TIS2000 service disks
on the laptop at home, not very user friendly but most of the tech.
info is on them. somewhere.

 

Engine type according to car ID plate = Z10SE/02PP4893

What year / engine is it? I do have a set of VX TIS2000 service disks
on the laptop at home, not very user friendly but most of the tech.
info is on them. somewhere.


Engine type according to car ID plate = Z10SE/02PP4893
Car on a 53 plate (October)

 

Z10SE = 1 litre engine? I didn't think they did one that little?
maybe it's Z14 or Z16 , assuming a petrol engine?

 

Z10SE = 1 litre engine? I didn't think they did one that little?
maybe it's Z14 or Z16 , assuming a petrol engine?

Yes you are right it is Z16 petrol poor printing my excuse

 

ok dokey, my tis2000 is playing silly buggers, so I'll check my Zafira
Haynes book of jokes, that should cover the engine.

 

ok dokey, my tis2000 is playing silly buggers, so I'll check my Zafira
Haynes book of jokes, that should cover the engine.


FWIW. the 'stat on our 1.8 zaf is a thing that comes complete with an alloy
housing, so wasnt cheap (an expensive VX part-now theres a surprise!) that
bolted to the front of the engine right next to the cambelt cover. Once I
removed that silly plastic lid on the engine it wasnt too bad to get off,
but a bit fiddley, is all. 15 minute job

Mike

 

Hi

sorry for the delay in repying my computer has been down this weekend

Just a question when your theromstate was faulty did the light with a car
and spanner come on?

pete