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MG MGF Technical - Coolant Temp

I was sitting in heavy traffic this morning for about 15 minutes when I noticed the water temperature was just tipping the red but the oil temp was normal.
I pulled over, switched off the engine and checked coolant level and oil level, everything seemed fine.

Should I get the car checked out because I travel in heavy traffic on a regular basis and the car has never overheated before.

BTW.
The car had been lying up for a week while in the bodyshop would this contribute to the problem?
DD

The fan is not spinning, or you have a stuck thermostat,
My money is on the fan, check the fuse, then if this seems OK the next thing to check is the temp sensor, how are you with electrics
Will Munns

Given the frequency of sensor failure, I'd say that you need to swap the ECU temperature sensor, DD. Occurs much more frequently than thermostat or Fan-related electrical problems. Had a very similar experience, and problem solved by replacing the 10 quid sensor :o)

Details: http://www.mgf.ultimatemg.com/hgf_pages/related_problems_overheating.htm
Rob Bell

Or of course some monkey in the bodyshop has disconnect the fan! What bodywork was done and how much of the mechanicals did they have to disturb?

Ted
Ted Newman

Thanks all,
I'll check this out..
DD


Hi all,

should really be no need to take away the clip, just press with a finger on the top of the clip and it will move further in. Then it is OK to release the electrical connector... Repeat above when re-installing on a new sensor.

BR, Carl.
Carl Blom

Or put another way, squeezing the connector will move the spring to alow release, if you don't know this then you might end up spending some large amount of time playing with plyers and searching the garage floor!

Will
Will Munns

>>should really be no need to take away the clip, just press with a finger on the top of the clip and it will move further in. Then it is OK to release the electrical connector<<

Argh! That'd have been easier! Great tip, thanks Carl :o)
Rob Bell

>>should really be no need to take away the clip, just press with a finger on the top of the clip and it will move further in. Then it is OK to release the electrical connector<<

I read this tip too late. Just spent a few minute looking for the bl**dy thing under the car. Easy to fit though just lost a egg cup of coolant in the process. One tip though a suitable ratchet spanner would have helped, access is a little resticted around the coolant pipes.

Tim
Tim

I must have had this happen 8 or 9 times over the years I have had my F. To start with I always had the sensor replaced but after it happening twice within 3 months I decided it had to be something else rather than the sensor. Now every 6 months or so I take the electrical connector off, spray some contact cleaner around it, and refit. Since doing this over the last couple or three years I have not had a problem. Takes 2 minutes once you have the engine cover off. As everyone says releasing the clip is the hardest part even when you know how it is supposed to work. Scrabbling on the floor to find it again is all part of the game.

Regards, Alan
Alan

Well I checked the fuses and connectors and nothing seemed to be wrong.
So my next step was going to be a new sensor, but guess what, while driving to work this morning in heavy traffic the fan started to kick in and the temperature stayed normal!

Hey presto.

Must have been a dirty connection :-)

Cheers.
DD

Something wierd is happening..>!!
On the way to work this morning, in heavy traffic, coolant temp went straight up tipping the red!
The car did not overheat and the fan did not cut in.

I turned the engine of while stopped in traffic but kept the ignition on so I could see if the temp was dropping.

I did this a couple of time but the temp did not drop at all.
Then I stoppped the car (High Temp reading), switched off the ignition and the immediatly started it up again and guess what, totally normal reading was displayed.

Have got a faulty temp gauge / sensor?

I would have thought if the sensor wa
DD

I'll finish that post ....
I would have thought if I had a faulty sensor that was reading a high temp that the fan would still cut in, no?

Would the fact that on both day's I was driving in heavy rain have anything to do with it?
Like damp getting into something?

Cheers.
DD

>Like damp getting into something?
could be

The sensor feeds just the ECU and another feeds just the gauge, so a failure of one will show up with the other. Also the radiator is remote to the sensor, with the engine still you cool the radiator but no water flow means the engine(and so sensor) stays hot
Will Munns

On a related note, ive heard the Elise has a electric water pump (think i read it on here!) that is switched on when the ignition is on, is this correct and if so could it be fitted to the f?
Mark Catterall

Will,
So there's a seperate sensor for the fan?
Maybe this is my problem?

Can anyone tell me where to find it and how I might test it?
DD

Well, the F has two sensors, one feeds the gauge, the other feeds the MEMS and is used for everything else, ignition timing, fan operation etc.

See Dieters site for pictures and resistances (you can use a multimeter to test) one sensor is brown, the is blue(?) they are next to each other.

Will
Will Munns

Thanks Will
DD

DD, the ECU temp sensor is brown. The guage sensor is blue. Both sensors are located on the engine outlet pipe, on the front left hand corner of the block (easy access when the engine inspection panel is removed).

More info on the aforementioned pages, including http://www.mgf.ultimatemg.com/hgf_pages/related_problems_overheating.htm and http://www.mgfcar.de/sensor/index.htm
Rob Bell

Rob,
So if the fan is not cutting in it's probably the Brown Sensor that needs replacing?

How will this effect coolant loss?
Do I need to take special care when raplacing.

Cheers.
DD

That'd be my bet DD. There are certain unusual aspects to the 'history' of this problem - the fact that resetting the ignition immediately normalised the water temperature reading. Odd.

However, if the ECU temp sensor (or its connections) are at fault, then overheating will occur - and the rad fan will not switch on. You may have noticed too that the idle speed may be a little on the high side? Again, a suggestive bit of evidence, as the faulty sensor will 'fool' the engine management into 'thinking' that the engine is cold, and will keep the choke open to suit.

A failed sensor will not lead to coolant loss per se, if that's the question you are asking?

Not much coolant is lost when replacing the sensor either. It is pretty easy to do yourself, and really not many pitfalls to be aware of.
Rob Bell

This thread was discussed between 22/11/2002 and 29/11/2002

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