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MG MGF Technical - Temperature gauge reading high

Usually the temp gauge in my 96 F VVC is rock solid on the normal mark. Tonight while travelling on the M6 I initially noticed it was about 3 mm above normal and then when I looked again (only a minute or two latter) it was fully in the red. I stopped on the hard shoulder and checked the coolant and this was at the normal level. I left the motorway and pulled into a pub car park. I switched off and called the RAC. While waiting I turned the key but didn't start the engine and long after the engine had run (60 minutes) the gauge was still reading high. The needle also oscillated. The RAC towed me to a garage who will investigate tomorrow. Any ideas on what has caused this? Has the engine over heated or is there a problem with the temperature gauge/sender/circuit?

Any ideas appreciated.
DW Staniforth

I have decided to change the temp gauge sensor unit in case that is giving false readings. I've bought a new one and removed the old one but they are slightly different in appearance. Is this acceptable or have I been sold the wrong sensor? Any help appreciated.
Dave

Are you Dave Staniforth??

Simon.
S McGregor

Yes I am.
Dave

Hi Dave,
do you work at Markem over in Salford???
Simon.
S McGregor

No I don't, why do I have a double?
Dave

Hi Dave, My old boss was called Dave Staniforth and lived over in Cheshire, just a coincidence with an unusual name!
Simon.
S McGregor

HI Dave,

Sorry this isn't a direct help to your question, but I do hope this helps.

I can't get access to the archive at work, otherwise I'd find the article.

BUt a while ago I had the identical issue, and of course you think HGF ???

I was driving along and as normal glanced down at the temp guage, it was in the red, so I pulled over at laybay and stopped. I have the B&G alarm and it didn't go off, so hoped I had water, and right enough I had water and levels all fine and thats why alarm didn't go off, as level was fine.

I allowed it to cool and water looked fine (no oil) and oil was lovely and clean.

Put question to this board.

is this how cooling works, it goes up into the red and then the sensor detects this red and switched on the fan and its then cools down needle drops and all ok ?

If I recall, the answers were no, the guage/sensor isn't the best, and really isn't sensitive to try and work out what temperature and needle actually mean. Have a look at the archives, as I can't fully recall.

Upshot is I did nothing whatsoever and its never happened again, since it happened I keep any eye on its, and noticed now that the fan comes on when in slow heavy traffic ( in general I use car for commuting so only ever in slow traffic in bomb scares and if someone crashes which, otherwise never any slow traffic, so not something I come across that often) but guage shows needed just above halfway, and never moves from this position, yet I did nothing ?

Brian

Sounds very much as if the gauge sender is faulty, which is a common fault IME. If the new sensor is black, whereas the old sensor is blue, that's 'normal'. The brown sensor is the sender for the ECU. I'd recommend cleaning up the contacts of both sensors with electrical contact spray while you're at it.
bandit

I have changed the sensor and the problem has not re occured, so it looks like bandit was correct. The old one was black and the new one blue.

Thanks for the help.
Dave

This thread was discussed between 14/05/2009 and 29/05/2009

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