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i have a lowe mileage 02 plate Vectra (B) 1800. The water temp is inconstistant and is bugging me! There seems to be no logic to the temp it sits at.It varies positions bewteen the 80 mark and just over 90. sometimes in traffic is near 80 and other times the temp is static for ages and unexpectably jumps up to 97 and the fan cuts in. Other cars i have owned the temp is pretty static. apparantly this is common for Vauxhalls?
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Normal running temp should be between 85 to 90 deg C (but more realistically 88 to 90 deg C) . With the fan kicking in sometime before 95 deg C.
Sounds to me like you have a lethargic thermostat. How long does it usually take to get up to temperature?
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How do you change thermostate. seems to be 3 bolts. do you need to move power steering resovoir. if so how?? black clip on top?
must be thermostat. Sat at 83 last night on dual and in traffic. (i pressume therm stuck open)95 on way home tonight and then suddenly drops. It went to 100 and suddenly dropped to 85. Then again to 100+. I stopped engine. restarted again and it went stright back down to 87! Fan did not come on at 100 (new switch) so i pressume water temp ok at radiator sensor as therm was stuck shut?
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I posted the same question some time ago and got this response. Hope it's of some use to you.
www.honestjohn.co.uk/forum/post/index.htm?t=20165&...e
Chris M
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Thermostat must be stuck shut now.Just went for a quick spin. Temp ok when driving 87 ish as soon as stop and idle for a while it shoots up and dont come down. I have borrowed all the torx tools.Been to all local motor factors and not got one. Some tried to sell me a housing that is to small or a kit for the small housing. vaux dealer wants £45 but still not have part in stock. QH dont list the part only pre 1999 1800's !!None on ebey. Went to non main dealer specialist.'' get the part so i know it is the right one and i will fit it''
On your old post you menion 2 torx bolts. mine has 3 ! 1 top left and 2 at bottom. there is hole in casting for temp gauge sender on right. on top some sort of another sensor and a thin rubber tube. and then main hose goes to right. Ahhhhhhhhhh now using 1966 Zephyr as everyday car.
What is the normal temp for an 1800 Ecotec?? So i am told the fan should cut in at 97and this seems to be the case. I think the thermostats i was shown today were marked 93??
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What is the normal temp for an 1800 Ecotec??
As I said previously. Normal running temp should be between 85 to 90 deg C (but more realistically 88 to 90 deg C). But the gauge is only an indication, not an accurate measuring device. So, if it does have a 93 deg theromostat in, the gauge could well read an indicated temp of 88 to 90 deg.
Try contacting www.autovaux.co.uk for the parts. Don't email them or order through their site though. The best and far quickest way is to ring them.
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If the gauge reading is seriously erratic, it might be worth checking the wiring between the gauge and the sensor. Typically any problems will be in the engine bay, or poor connections in any multiplugs that the wire goes through. There is the obvious multiplug on the back of the instrument panel, and, I would imagine a multiplug in the engine bay (although I'm not sure about exactly which multiplugs on this car)
As it is a Vactra B, at least you won't have any CAN bus nonsense to contend with!
I've seen some thermostats become erratic on their first opening of the day - i.e., allowing the engine to get worryingly warm before opening for the first time, but I haven't seen one as erratic as you describe.
Is the fuel gauge also erratic?
If so, you may look at the power supply to both gauges.
If not, then the power supply is OK, and you may consider the temperature gauge itself, the wiring, or the sensor.
As you say above that the temperature changes between switching off and on, it seems unlikely that the temperature reported by this gauge has any basis in fact - has your car ever overheated? boiled over? lost any coolant?, or is it just the dashboard gimmick that is causing trouble?
Number_Cruncher
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Cheers guys. Fuel gauge ok. Drives great. Never over heated, lost water or boiled over ! Had it from new. Been very reliable. It is a '2nd car' to go to work on rainy days when i cant use a classic.
It is the dashboard gimmick that scares me when it suddenly jumps from normal upto 100 + !!
Radiator is hot. no cold patches. top and bottom radiator pipes are hot.
Will do thermostat change and hope that sorts it. I am worried it is a head gasket problem.
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Ah!, if the gauge suddenly jumps about, and goes over 100 and you don't boil over, check the wiring very carefully between the gauge and the sensor for any shorts to earth - anywhere where the wiring runs close to the bodywork or the engine, check to make sure the wiring hasn't chafed through.
If this wire does short out, the gauge will shoot up - as the engine wiggles around on its mountings, any shorts can be intermittent, and difficult to find.
Obviously, fitting a new thermostat is probably a good thing, but I'm not sure it will cure the fault - I suspect the gimmick!!
Number_Cruncher
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took it to vauxhall independent garage this morning. thermostat changed. plugged into computer. all seems ok now. temp sitting steady at about 87. Put boiling water over old thermostat. took ages to open up a bit .
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Gauge is jumping to red again. Sudden jumps up. Turn ignition off and start and back to normal! Must by gauge or eletrical ????? Garage says it could be cracked head and sell car . Great Help. Just had car in drive for an hour and no problem. Sits at 88 goes up. Fan comes on at 92 and temp goes down and fan off.
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If it's a cracked head, then the garage should be able to tell by testing the coolant for hydrocarbons using a gas analyser.
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if cracked head why so intermitant? 99% of time it is Ok. No oil in water or water in oil. no water loss in 4 years!just sat in drive for ages whilts i wiggled wires and it was fine. i am thinking of buying an after market water temp gauge and wiring that it temporaly to see what that reads.
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When you say the gauge moves suddenly, how quickly do you mean? How many seconds does it take to go from a normal reading to an extraordinary one?
There's a limit to how quickly an engine will heat up, but if there's an electrical fault, the gauge can move much quicker.
The more I hear, the more convinced I am that there is an electrical fault. I think that checking the wiring is something you can easily do your self - it may be worth looking for places where the wiring may rub against anything metal, engine or bodywork/
Good luck,
Number_Cruncher
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i prefer to hear eletrical fault. the speed matches the dial coming up on a warm engine when you turn the ignition on. it is not an immediate jump to the top. it is a rapid climb ie 2 or 3 seconds. does that make sense? i will check wiring tomorrow night. pouring down with rain now.
Thanks to everybody taking the trouble to reply. I have tried 2 garages now. I want to avoid the main dealer!
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As it's taking seconds, it sounds like an electrical fault - the gauges aren't that quick to respond themselves, because the phenomenon they measure can't change quickly - the thermal capacity of the engine is massive, it takes a lot of thermal energy to produce a rapid change in temperature.
If the engine were really overheating, I would expect the gauge to take minutes to climb.
Number_Cruncher
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Would it be worth temporarily disconnecting the wire to the temp sensor and seeing if the gauge still misbehaves? Or does the sensor serve other purposes, such as communicating with the ecu so that it knows what temp the engine is running at?
what about grounding out the wire from the sensor to the engine block to see if the gauge goes FSD or not to verify the gauge is responding correctly?
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Yes, I think they are good suggestions DD.
I don't think that the temp sensor for the gauge and the temp sensor for the engine management are one and the same on this car. If they were, there might have been some activity from the engine management light on the dashboard too.
However, even if I am wrong, the worst that will happen is that a fault will be stored temporarily, which will erase itself after 30 or 60 ignition on / off cycles depending upon the model year.
Number_Cruncher
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An intermittently faulty temperature gauge sender on our (now departed) H reg 1.1 Fiesta gave a similar fault. Occasionally the gauge lept into the red. Quite alarming but the engine never boiled up. A new sender cured it. However this was before the days of ecus.... Good luck.
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On the thermostate housing there is the temp sender for the dash gauge and another sender which goes to the ECU management system? I pressume as no other warning lights then engine is not over heating. Vauxhall delear has suggest i replace radiator expansion cap which i have done. will check all wires tonight. local motor factor does a water temp gauge and sensor so i may disconnect vauxhall one and try one of these tomorrow.
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the only obvious thing i have not done is completely drain and replace the coolant. it had a service 4000 miles ago but no proof garage did drain and change. now 4 1/2 year old car with 34K on clock .
I am running out of ideas.
Changed Stat, rad cap, rad sensor and gauge sensor. Now sitting at 92.
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>>I am running out of ideas.
If there is enough coolant in the system, you don't need to change it - it won't fix an electrical problem!
Don't give up now - I think you are getting close.
That there are two sensors means as you say one is for the gauge, and one for the engine management. So, we know that the problem is with the circuit or wiring to the smaller sensor, the gauge itself, or the sensor itself.
As you fault is intermittent, I can imagine that wiring rubbing to earth somewhere is the most probable problem - and by far the cheapest to fix. Check the wiring very carefully.
Next in terms of probability and expense is the sensor.
Last is the gauge itself - I would be surprised if this were at fault.
Number_Cruncher
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Check the engine to body earthng strap. I suspect the engine is earthing through various other paths, including the temperature circuit.
------------------------------
TourVanMan TM < Ex RF >
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checked everything this morning.
did 30 mile run sat at 88 all the way inc heavy traffic. great !!
on way home doing 60 it sat at 95 and 100+ in traffic. Fan was on. Had to turn car off in Q's.
Booked in to main dealer Tuesday.
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I forgot to say-
I used to use a variable resistor between the disconnected sensor wire and earth to check the gauge out. For full scale deflection, typically, you will need a resistance of 100 Ohms - then, as you turn up the resistance, the gauge should fall. The current in these circuits isn't large, so virtually any variable resistor will do, as long as it goes below 100 Ohm, and above, say, 5K Ohm
If you set the resistor up to give you a sensible reading, say 3/4 of fsd, with someone watching in the car, you canwiggle all the wiring and connectors, and see if there is any movement in the gauge. Its much easier, because you cando it with a cold engine, with no risk of overheating, and if you see a change, you *know* it's nothing to do with the engine itself.
Number_Cruncher
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did not undestand that but my mate is an auto electrician.
Still convinced not really overheating
it was at 110 but the coolant was not boiling nor the pipes hard. you could still sqeeze. it did not smell hot. it was running fine???
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Sorry if my post was confusing. I was describing how you might substitute a variable resistor (think volume control on a radio) for the temperature sensor - because all the temperature sensor does as it heats up is to reduce its resistance - so, you can simulate it, just using a variable resistor. It saves you from having to warm the engine up, or wait for it to cool down if you suspect an electrical problem rather than a true overheating problem.
Number_Cruncher
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had friday nigt KFC with car club mates. One is an auto electrian. somebody earlier suggested this -
'what about grounding out the wire from the sensor to the engine block to see if the gauge goes FSD or not to verify the gauge is responding correctly?'
so we tried it. engine warm. ignition on temp sat at 80ish. removed wire from sensor temp gauage was completely down. touch wire on block. nothing. put wire to - term on battery. nothing.
very strange !! put back on sensor went back to 80is
Is it a faulty gauge? all other cars we tried the gauge maxed out.
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Don't fall into the trap of thinking that the numbers on the dial are the actual temperaures-they're only indications-the guages are not that well made.An engine running normally should be roughly in the middle of the scale.There is a lot to be said for the blue,white,red type of display.
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>>Is it a faulty gauge?
I very much doubt it - the variable resistor test I have mentioned will check this out properly though.
When you shorted the wire to earth, did the gauge not even twitch from zero?
If this car were my problem to sort out, I would either pick apart the loom and check the wire that goes to the sensor**, or just run a new wire from the instrument panel, and tape it into the loom. I think the existing wiring is probably damaged, and as soon as you move the connector around, you break the circuit.
** although on a Cavalier, I once dealt with a very similar problem. The customer complained of overheating going up hills, and the car had been in and out of the garage a good few times, without being cured. After making sure that the overheating wasn't real, I traced the wiring back, checking with absolute pedantry. The sensor wire was shorting on a sharp edge as the loom went past a rib the gearbox towards the multiplug by the battery. The nick in the insulation was tiny, barely more than a pin-prick. As the engine and gearbox moved on the engine mounts under load, the wire was shorting, and sending the gauge reading high.
Have you checked the wiring in this level of detail?
Cleaning the earths, as TVM suggests, is always worthwhile.
Number_Cruncher
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i like the idea of running a new wire. how do you get the dash clocks out or behind them?
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Rather than go all the way back to the clocks, it might be easier just to go back to the engine/body multiplug.
Number_Cruncher
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yep just seen how to get dash out !!! no clear wire behind dash to water temp gauge !!
www.vvoc.com/forum/showthread.php?t=21449&highligh...h
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BTW, I was suggesting running the wire just as a quick diagnostic check rather than a permanent solution. The permanent solution is to find the fault, and repair (or replace) the wire properly. I think any wiring fault is much more likely under the bonnet, rather than under the dash.
The wire from the instruments will leave via the instruments multi-plug. To trace it via its route along the loom, you will need a wiring diagram, which should also give you the pin numbers in the multi-plugs.
Number_Cruncher
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One of my customers did a free diagnosis check today. no faults found. non recorded. did a live test on temp comparing gauge with ECU temp sender. Matched but gauge did not go into red or above 95 before fan kicked in . Typical...like going to the dentist and the pain goes.
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striped cooling system down today and back flushed radiator and block. full of gritty silt particals! so bad even header take had grit in it. does seem services were not done correct nor coolant changed. this could be my problem ??? i can only hope. we had to sit revving engine ages for it to heat up and put fan on. fan brought temp back very quickly to normal
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one week one and running great !
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