Water Temp Gauge 98 GT3 or sensor ?

[benters]

Guys, after a new radiator a couple of hundred miles ago, the car is running fine and dandy. However without any relevant traffic related conditions and according to the gauge the needle will on occasions creep quite quickly up and then down again. Sometimes it reaches 110 and then falls back to its normal running position of 80c . . . . .this all happens in a matter of a minute, so I assume its the gauge or sensor. Anyone got any experience on this ? The coolant level light stays out, so I don't suspect anything other than a duff signal. . .as a further test, in a start up and leave to warm up cycle the car gets to temperature, the fans kick in and all seems normal. . .the fact that it appears to be random makes me think it is the sensor but does  anyone have any wise words ??

[CarBuff]

Have you topped-up the coolant since the rad job?  It's normal to have a few air bubbles in the system, at first. Takes four or five drive cycles to get all the air out.

 

High-RPM running is another good way to purge air.  It's FUN, too.

 

BTW the coolant level sensors are known to stick, so you should not ASSUME that the level is OK.

[benters]

cheers for your reply, the car has actually done 700 odd miles since the rad job (forgot my Christmas trip) and I have kept my eye on the levels as you might expect.. . . I will double check again tomorrow.

Edited February 5, 2016 by benters

[CarBuff]

Your GT3 has the plastic header tank, right?  Might be wise to look closely to the right of the cap and an inch down, cracked plastic could mean that the cooling system won't hold pressure.

If the overflow reservoir is in the RH wheel well, check to make sure THAT is half-full, and the hose to it isn't clogged...

 

[benters]

It does have the plastic tank you are right, the part which generates the low coolant level was also checked, I know this was looked at as was the expansion tank, so a check over again certainly is a good idea. I will report back.
I assume there is a way to check the read out of the temp sensor ? did I read somewhere it is all to do with resistance ??
 

[Chillidoggy]

Are you losing any coolant, and is the correct header-tank cap fitted? It should have a rubber seal to prevent coolant loss just under the top of the cap.

[Whirlybird]

Mine did exactly the same thing, had since I got it so I thought it was normal.

I took the car to sparky a while ago for him to fit a charge cooler pump. I mentioned how hot it got, he said it wasnt right and found the cable going to the sensor not seated correctly. Pushed it back on and now all is fine.

and once sparky is a hero. ?

[benters]

thanks for the various suggestions, the caps were round the wrong way originally this was discovered sometime ago before the radiator self destructed, so I know this was changed, the level indicator in the plastic header tank was also looked at and this appears in order too. as for the the sensor and its seating, from the brief look I had yesterday it looked ok, providing I was looking at the right thing. . . .I assume its the one buried under the multiple hoses above the starter motor ??

Just to be sure the fans were cutting in I ran the car yesterday and they fire up just between 90-100 on the gauge and quickly get to work so I am comfortable they are getting the right info to work, as they shut off a minute or so later when the temp goes down.

So best I hunt out the sensor. . .

Edited February 8, 2016 by benters

[fjmuurling]

The SE has two tempsensors one for the ECU and one for the dashgauge. The ECU one sits in the engineblock and the one for the dashgauge is at the water(coolant)pump in front of the engine.

[benters]

cheers for the info Fjmuurling. . .I will investigate again. . .with a torch !

[benters]

well during and since the weekend trips, which must be 500 miles plus all has been normal, and this includes sitting on the M3 for 40 mins. So whilst I am not considering it 100% cured, it hasn't happened again ! 

[Jacques]

But what did you do to the car, since it began to work normal again?

Kind regards,

Jacques.

[benters]

17 hours ago, Jacques said:

But what did you do to the car, since it began to work normal again?

Kind regards,

Jacques.

nothing !
I guess something is on its way out, but it seems to be behaving at the moment, perhaps has its a 98 car its having a teenage moment !

[ajheath]

Seems a common problem, Ive had issues with mine nearly all the years ive owned the car (12).  A couple of months ago the needle on the gauge just decided to go all the way to the right and stay there almost as soon as the engine was fired up.  Im just detailing my engine so while Ive got the chargecooler off and the system is drained down im replacing the gauge sender which is the most likely culprit.  What age is your GT3, pre or post facelift?

One way to be sure everything is ok is to use espritmon to check engine temps and when the fans kick in.  Mine is fine, its just the gauge thats dodgy.

[benters]

2 hours ago, ajheath said:

Seems a common problem, Ive had issues with mine nearly all the years ive owned the car (12).  A couple of months ago the needle on the gauge just decided to go all the way to the right and stay there almost as soon as the engine was fired up.  Im just detailing my engine so while Ive got the chargecooler off and the system is drained down im replacing the gauge sender which is the most likely culprit.  What age is your GT3, pre or post facelift?

One way to be sure everything is ok is to use espritmon to check engine temps and when the fans kick in.  Mine is fine, its just the gauge thats dodgy.

Thanks or your input, mine is a 98 late dash model.
I will double check the wiring connection for corrosion etc over the weekend.
I haven't tinkered with Espritmon. . . . . .computers are like witchcraft to me !

[ajheath]

for reference mines an early GT3, built 96

[benters]

had another look at the engine and what I thought would be the connection to the sensor (spade connector) to thermostat looking thing, Pulled it off expecting the gauge to read right across to hot as I am told they do when disconnected and nothing changed. The car was warmed up at this point.
So, I guess I pulled of the wrong wire. . . .should have taken a pic, but didn't.
Otherwise, went out for a run in it on Sunday and it behaved itself, even getting a thumbs up from a dude in his SLS merc !
Just goes to show that a certain type of car nut appreciates seeing an Esprit on the road. . . .

[benters]

Further on this, I called in at Lakeside Engineering and Max kindly pointed out that the wire/connector I had looked at was the right one. He suggested I remove and clean out the coolant level tube, which I did and to be fair muck did come out, but nothing has changed. The car on idle saw the temp go up and down on the gauge, its clearly a temperamental thing. . . . .anyone know where I can get a gauge ? He further suggested checking and if need be cleaning up the earth points around the engine, which will be this weekends tinkerings