Overheating Issues MGF VVC

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Claire_MGF_VVC
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Overheating Issues MGF VVC

Post by Claire_MGF_VVC » Mon Apr 24, 2017 10:48 pm

Hi, I am not mechanically minded so please excuse the lack of technically language etc used in my post. I was hoping I can get some advice before I head off to a garage.

I have a TF on a W Reg that has done 64,000 miles on the clock and had a head gasket replacement by the previous owner at 45,460 miles. I've owned the car for 2 years and use it as my daily so have clocked up about 15,000 miles.

For the past 6 months the engine temp gauge has been intermittently increasing when stationary after a long run. The temp gauge has also risen to about 3/4 a couple of times if I have left the car to warm up. The car normal temp (well what I have known) is just under half. The front fan does kick in but it has become more noticeable recently, kicking in more (I believe it has had a new radiator at some point but I need to look through the history of the car). I have never noticed the side intake fan work but does it work at a higher temperature on a vvc? I did check the fan to see if it was physically seized and it isn't.

The car has only boiled once because it happened so suddenly and it did overflow from the coolant bottle/cap. I came back on a recovery truck as I was fearing that it was HGF but I was told by the local garage that a replacement bottle/cap and bleed would hopefully fix the problem. That was 5 months ago, it did initially work but I am now in the same boat as I was before it boiled.

The internal heaters work brilliantly and blow hot air but surprisingly (or maybe not to you) the engine temp gauge lowers if I put the heating right up, so if I have been sitting in traffic and I have seen the temp start rising above half on the gauge I will put my heaters on which stops it from rising further. Is this normal?

I haven't checked any fuses or cables as I don't know where to start. Any help in this matter would be much appreciated, I do love this car, it's great fun to drive and I want maintain it so I can have some fun in the future.

Thank you in advance.

Claire

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talkingcars
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Re: Overheating Issues MGF VVC

Post by talkingcars » Mon Apr 24, 2017 11:22 pm

Hi and welcome to the forum.

I would start with replacing the header tank again and then rebleed all three points. Cooling system info here.

Let us know how you get on.

James
Home to black Alfa 159 3.2 V6 Q4, blue MGZR160, green MGF VVC and grey MGF 1.8i, and red MG Maestro T16.

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daz
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Re: Overheating Issues MGF VVC

Post by daz » Mon Apr 24, 2017 11:42 pm

I'd see about having a look at the ecu to see what the temperature actually is. It sounds to me like it could be an expansion cap problem or a thermostat problem. When you put the heater on it sort of opens up another much smaller radiator (Heater matrix) hence the temp drops.

If you can get someone to get under the front of the car when it's up to temperature & feel both pipes attached to the radiator, they both need to be the same temperature, if there's a difference the coolant isn't pumping round correctly.

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Rob Bell
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Re: Overheating Issues MGF VVC

Post by Rob Bell » Tue Apr 25, 2017 12:28 pm

Claire_MGF_VVC wrote:For the past 6 months the engine temp gauge has been intermittently increasing when stationary after a long run. The temp gauge has also risen to about 3/4 a couple of times if I have left the car to warm up. The car normal temp (well what I have known) is just under half. The front fan does kick in but it has become more noticeable recently, kicking in more (I believe it has had a new radiator at some point but I need to look through the history of the car). I have never noticed the side intake fan work but does it work at a higher temperature on a vvc? I did check the fan to see if it was physically seized and it isn't.
Hi Claire,

Welcome to the forum! And a great description of the problem :)

A car that only over heats in slow moving traffic, or when stationary is usually one thing: a seized radiator fan/ blown fan fuse. However, in your case, it does seem to be working? How can you tell this - the rad fan is generally audible only from the front of the car, and is usually quite difficult to hear...

You've checked the side fan, but that only serves the engine bay - and doesn't contribute to coolant temperature in any meaningful way, so unlikely to be this.

A failing header tank and/or cap will lead to coolant spewing out and over heating, but that needn't necessarily require the car to be stationary to get that. A sticking thermostat will likely lead to a rising temperature needle at higher engine loads - and is certainly a possibility here.

Daz has suggested a good test of this problem (feeling the temperature of the coolant hoses - accessible from the spare wheel well under the bonnet - if both are cold and the engine is hot and overheating, you have your problem identified).

Let us know how your investigations go! :)

Claire_MGF_VVC
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MGF Register Region: Midlands

Re: Overheating Issues MGF VVC

Post by Claire_MGF_VVC » Tue Apr 25, 2017 6:15 pm

Hi All

Thank you ever so much for all your responses I'll definitely get them looked at :D

Rob - I can hear something starting to whirl when I'm sat in the car (it sounds like a fan blowing) and if I leave the car and walk to the front I can hear it so I am presuming it is the radiator fan. As I can hear it while I'm in the car, is radiator fan being too loud? (Sorry I know that sounds like a daft question to ask!).

I did 80 miles (160 round trip) non stop today, first on the motorway and the temp gauge went up slightly when I stopped in traffic but I put my heaters on it never really rose about half way. After my meeting I took the scenic route back which was relatively clear and I had no issues at all. I left the car to warm down, left it to idle and I was was expecting the temp gauge to rise but it never did.

I will keep you all updated on progress and Thank you all again for your advice.

Claire

john_g
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Re: Overheating Issues MGF VVC

Post by john_g » Wed Apr 26, 2017 7:48 pm

hi Claire, I am in exactly the same boat..
I rebuilt my TF when I bought her, and have done about 10K since then.. but recently I have noticed the front fan a lot more..most times I use her really..

The cabin temp is usually set to hot as I am a cold reptile, but I did notice the other day turning from cold to hot brought the gauge down noticeably. (which makes sense)

I did check under the front as she was warming up, and both rad pipes were warm

I have a theory, Rob mentionied it above .. when i rebuilt the engine I did my best to flush the cooling system, but I wonder if somewhere was not cleaned too well.. that place could be the thermostat.. The car doesnt seem to heat up very quickly anymore either.. a good few miles needed even on a warm day..
I have no oil / water mix and no obvious coolant leak - possibly a small one that I fixed a few months ago.. the car once did bubble out of the expansion tank when on holiday, but not since then (although has got close) - i note the coolant level when the gauge has gone high is a long way up in the expansion tank!

So, to summarise, she has shown signs of overheating since the rebuild (more so recently), I have never let her get beyond 3/4 gauge.. I have put a little coolant in over that time, the normal gauge reading is always just under half..the oil temp shows the imminant coolant rise, once it gets to 120 (seen from drivers view) I know its getting warm back there.. the car takes too long to warm up for a petrol, i have never replaced the rad cap or tank!)

John

ps she overheated like this last week.. i stopped and didnt do much else, waited, then proceeded to destination and she stayed normal!

pps I have bled so so so many times, often with the rear in the air..

ppppps I can hear the fan quite easily from inside the car, if no other noises

ppps I dont get the possible overheat scenario when idleing..it need some higher revs and wind resistance I think,.,

@ dev and others , in my case if ,for example, the stat was stuck half open it could cause my issues? low flow and a long time to heat up.. quite why it seems to have become worse is a slight mystery..maybe its clogging up more because of a blockage? I am guessing the stat (PRT) isn't rebuildable?

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