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MG MGF Technical - Overheating (or not ?)

Hi all,

touch wood, my TF doesn't have such a problem, but I post this for a friend who unfortunately encountered this :
(It's a 2002 TF135 with 75.000 km)
His water temperature gauge goes up, rather when idling for a couple of minutes than when driving at speed.
He had the head gasket replaced for this reason by the dealer, but this phenomenon still occurs.
The dealer has the car now again and he doesn't know what to do (!).
What would be the areas to look for ??
- a proper bleeding of the cooling system, I mean checking that there are no air bubbles ?
- the jiggle valve stuck ?
- the thermostat not opening ?
- the cap of the expansion tank that's defective ?

Other suggestions ?
Could this just be a sensor ?

(BTW, in all these scenarios, when the dealer changed the HG, he should have seen it was untouched...)

I don't know that dealer. It's not a new one and he has rather good reputation ; it's now the only one in the area cos our usual dealer has "lost" its mg-rover franchise after the boss died ; the repreunor only kept the Jaguar and Land Rover branches.

thanks in advance,

Fabrice
Fabrice

blown fan fuse, stuck fan, faulty brown sensor in that order
Will Munns

Hi Fabrice,
IMO no MGF or TF can be left idling for longer periods without the temperature is gradually rising.
Not even with rebuilt cooling system ! I did experience this on my own F after testing the rebuilt system also on prolonged idle.
I do remember that Roger P. mentioned something about this a few years ago when it was brought up.Probably has to do with too low coolant flow in the system at idle. Even if all systems (fans, thermostats etc.) are OK this seems to happend ! Flipping the throttle now and then when standing still in traffic seems to be needed to get enough circulation. / Carl.
Carl Blom

Observed the same problem on a mate´s volvano VVC. Tried everything in you list. In the end, he changed the rad vent and it got solved. Coming to think of it the vent made a screaming noise once and a while

succes
david
David Peters

My water tempature gauge sits at one under the halfway mark even on 40o days and stuck in long traffic jams.
Should not move BUT does not sound like HGF.
Andrew Regens

thanks for your replies!
I should add this:
I had my friend's TF for an afternoon (before he had the head gasket changed) to look for obvious causes...
Both radiator and egine bay fans are working fine.
The temperature rises *rapidly* at idle when the engine is hot, I mean after not even 2 minutes, whereas for 6 years with my F, I've never seen the gauge above halfway.

What's the brown sensor ?
a temperature sensor that triggers the rad fan ?

Hi David,
A weak rad vent ? I'll keep that in mind, you'll never know...

Cheers all,
Fabrice
Fabrice

Problem is likely the temperarture sensor. It clips in. If you unclip it and spary the sensor contacts with WD40 or similar this should solve the problem.

Common problems with MGF's.
Graeme Wardrope

update :
my friend got his car back on Friday. The dealer said "he found some strange things and did fix them", but when my friend asked him more precisions, the dealer's answer was vague and he said to drive the car to see how it behaves. What he did.
On Saturday, the engine temp was perfectly ok at halfway mark.
On Sunday, he did a longer drive (60 km) on the motorway and temp was OK. On the way back, the temp began to rise. He stopped and waited a couple of minutes. Then he drove carefully back to home, but unfortunately, just when he arrived at home, there came the (in)famous cloud of steam from the engine bay :-(
The assistance truck brought his TF to the dealer and this morning the dealer said the engine had to be "completely stripped down" because it was "a very serious failure"...
The biggest problem is that, although beeing less than 3 years old, his TF is 2nd from France and then not under warranty in Belgium.

This is really strange...
Any though on possible causes ????

thanks in advance,
Fabrice
Fabrice



This happened to my F TWICE at three/four years old and the cooling sytem was at fault.

Both times I was lucky and saw steam and water temp gauge of scale high.

The AA tested coolant for cont

I would not assume HGF just cos your friend saw some steam and the dealer says so.

To your own and Will Munns suggestions of

a proper bleeding of the cooling system, I mean checking that there are no air bubbles ?
- the jiggle valve stuck ?
- the thermostat not opening ?
- the cap of the expansion tank that's defective ?
blown fan fuse,
stuck fan,
faulty brown sensor

I would suggest the following

resevoir cap
examine radiator (mine failed soon after last boil up and has been fine since)
Check coolant pipes
PRESSURE TEST THE COOLING SYSTEM
Check water level often
always carry some water

Esentially make sure, if you can, the cooling system is sound before the engine gets expensive work.

Personally I have an excellent back street garage and can talk to the proprieter/mechanic and trust him.

Regards David
D Brunton

I had a very similar problem with my MGF VVC '97. When engine nice and hot, leave it for 30 secs and the water temp would start to rise very fast, if I revved the engine to 3000+ and force more water round the cooling system it would drop back down again. Leave it for a further 30 secs and back up it would go again.

I took it to the MG garage numerous times without any joy, they wanted to replace the head too. (A month prior to the problem I had a HGF and had the head skimmed)

The problem was resolved when I took it to a backstreet garage and they serviced the car and completely drained and refilled the cooling system. I think it was probably an air lock or something similar, maybe from the HGF work the MG garage had done.

Sorry I can't tell you what the exact solution was.

Regards

Nigel.
Nigel Blackburn

Thanks David & Nigel, your posts confirm my first impressions.
The last news is that the dealer now wants to dismantle the block to check it's not cracked and to check the liners...
This sounds strange to me. I agree that a HGF could be caused by these things, but overheating ??
Fabrice

This thread was discussed between 03/02/2005 and 08/02/2005

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