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MG MGF Technical - mgf 97 OVERHEATIN PROBLEMS

My MGF have problems with it's coolig syystem, it overheat and I have had it to the dealer they put in new thermostat and also the thing that measure the temp (don't know the name in english, sorry)
Do anyone know what it coul'd be?
KNUT

KNUT, if you register as a member (free) then search the archives for 'overheating', 'cooling', 'radiator' or other keyowrds you will find a wealth of information on cooling problems. 'Temperature sensor' is probably the term that you were looking for.

First check I would do is to see if the overflow tank cap has a small white dot painted on it. If it hasn't, then get a new cap. If it is old, perhaps get a new cap anyway. If the pressure is not high enough in the cooling system it will blow steam out the cap.

If you are loosing coolant, perhaps the pipes to the radiator need checking. These can fail after a number of years and may need replacing.

What year was your F manufactured?

Whatever you do, though, be VERY carefull. If you loose all your coolant and don't notice, an HGF is just around the corner. This is very expensive. Don't rely on the temperature gauge to tell you if you have cooling problems. If this starts to move, it is probably allready too late and the head gasket has gone.
Neil Courtney

When you say it overheats - what actually happens ?
Does the temp gauge go high - or does steam come out of the car ?
If the front (radiator) fan does not come on then you probably have a blown fuse.
If you are losing water then you either have a leak, or the system can't maintain pressure. Check that your oil level is not rising, and the oil is clean.

Plus everything that Neil suggests.
Steve

Knut,

If your front radiator fan is not starting, have a look at ......

http://www.apttony.co.uk/Servicing/WarningLights.html

It may simply be a poor electrical connection.

Tony
Tony

>>If the front (radiator) fan does not come on then you probably have a blown fuse.<<

From the experience on these boards Steve, it is probably more likely to be a problem with the water temperature sensor - but I agree with your check list.

Knut, can you give us more details regarding your overheating? When does it occur? In stationary traffic, or on the move?
Also, do you have coolant loss (as Neil was asking?)

If overheating in stationary traffic - see http://www.mgf.ultimatemg.com/hgf_pages/related_problems_overheating.htm
Rob Bell

Hi all and thank you for all your kindly advices!!
My mg is an 1,8 (not vvc) manufactured in 1997
1st time it boiled was after driving a small hill,
the temp gauge went high and steam came out of the expansiontank in the engineroom. The first time i do not think the radiatorfan started. At the garage they put new thermostat and a water temperature sensor.
Because of the pressure when boiling i missed water but i do not think i have any leak. athe oil is clean, I as all others had a headgasket exchange at 78000 km.

2.nd time was yesterday, at the exactly same small hill!?!, i do think the fan started this time, I turned the car went to fill water and drove home, this morning everything was ok i drove 15 km. Now the car is at the garage and I am driving their car they borrowed me- an 1986 Mazda 626 hmf...
Today I have found som info at Dieters homepage about bleeding, I will also give them a copy of your sugestions, hopefully they fix it tomorow!
I promise to tel you the and of the story!
Again, thanks for all

Knut Osborg Oslo, Norway
knutos

Hi Knut,

I think it's the headgasket then, as they changed the ECU related sensor already and you didn't find the fan fuse blown. :(

Can you add the date/year when the gasket got changed for the first time ?
If done before March 2001, then you did not get the newer spec gasket with steel dowels fixture.

btw, I think Jon Fredheim (Merc mechanic) http://www.mgfcar.de/hgf/index.html is near Oslo ?

Regards
Dieter
Dieter K.

I know I have got the newer spec gasket with steel dowels fixture. I had this problem in october 2001 and the dealer told me that he fittet the new gasket. I realy hope you are wrong, when i drowe my car this mornig i didnt feel or hear anything that indicate thet the gasket er blowb again. Last time that happened the engin stopped and a lot of smoke came out from the engine room.
I hope it is bad bleeding, or the cap on the expanding tank, or really I dont know:(
I will go the garage tomorrow to tell them to check the oil

Knut Osborg Oslo, Norway
knutos

To be sure that the radiator fan is coming on properly, you need to run the engine whilst the car is stationary for a period of over 30 minutes. Stand in front of the car and listen out for the radiator fan (it is quite quiet).

If there is no fan and the water temperature starts to rise, then you've identified the problem to the non-operation of the fan that will either be the fuse or sensor/ sensor connection.

If the fan comes on as it should, then suspect the expansion tank cap. It may have been recently replaced, but it is not unheard of for new caps to be faulty. I'd suggest replacement.

All the above assumes that the oil on the dip stick looks like oil (and not a brown coloured mayonase) and the coolant is clean.

Fingers crossed that the head gasket remains intact. Good luck Knut
Rob Bell

I agree with Rob (what else), the fan test is the first way to go. It can last half an hour or more until the fan comes off.

Regarding the cap replacement, there's another subject. May be the coolant expansion tank got overfilled at any time. The cap doesn't like that. Good advise on the expansion tank can be found on Paul's site.
http://homepage.ntlworld.com/dotcomoff/home/motoring/mgf_faq/diy/engine/coolant/level.html
I like that figure one :)

>but it is not unheard of for new caps to be faulty..

I'm on the third cap meanwhile 2 years now ;)

HTH
Dieter
Dieter K.

I have the original cap, and am goig to buy a new one tomorrow.
I really apreciate all the good advices i have got today, thank you all.
Knut
Knut Osborg

Have you had a new radiator yet? The one on my '98 was in a bad state when it was replaced earlier this year. Could be this that's the problem?

Leigh
Leigh

<Have you had a new radiator yet? The one on my '98 was in a bad state when it was replaced earlier this year. Could be this that's the problem?>


Or a thermostat that does not open when working temperature is reached? Then the only cooling will be through the heater.
Jon

This thread was discussed between 09/10/2003 and 12/10/2003

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