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MG MGF Technical - Cooling system problem

I was sent this email today, it may even be from someone here, I don't know. I do have a couple of ideas about the problem described but would like a couple more opinions before replying - anyone here recognise this problem?

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I was shown your site by an engineer who works in the company where I work, here in Switzerland.

I don't know if you can help me. I have a problem with my MGF that my garage does not seem to be able to resolve.

Last year, in August, I had to replace my engine because it 'seized' up. The oil level was fine, the water was fine. They couldn't find out what the problem was. The engine had done 120,000km. The car is 5 years old (June '98).

At the time I was having the car serviced by a Porsche garage (they had assured me that they would be able to 'look after' the car!). They found me a 'second-hand' engine and when I felt it wasn't running right, I took it to an MG garage where they told me my car was 'illegal'! The Porsche garage had put in an MG Rover engine for a 4x4!!!

I ordered a brand new engine and have had the car looked after by the MG garage since then. Everything seemed fine through the Autumn and Winter, apart from my noticing that the car didn't seem to heat up as well before (the garage tried to tell me it was because I was going 'downhill' to work, about 10km, and the engine isn't being worked hard enough to heat up - this is the first Winter I'd had this problem!),

My problem started one day in April last year. After having spent a winter where my heater did not seem to heat up very well I turned the heater off one fine Spring day driving home. The following morning, not realising that the heater was still turned off, I suddenly noticed the needle on the temperature gauge was already up at the 'Normal' position! I had not even gone 2km to the neighbouring village!

I then turned the heater on to the maximum position and turned on the fan. The temperature gauge needle moved fairly quickly back down to the cold position and the air coming from the heater was also cold. The needle stayed on the cold position until a few kilometres further on and then it started to move up slowly as it should normally.

After replacing the thermostat and 'bleeding' the system, I wrote to MG UK and they suggested that the radiator needed changing. I had it done last Thursday and the problem is still there. You can imagine my frustration, not to mention my anxiety that this problem may have been the cause of my engine seizing up last year - and I don't want the same thing to happen this year!

This week, my garage want me to take my car in one evening, give me a replacement car and, keeping my car keys with me, they want me to go back to show them what I 'think' the problem is. This last week I have been dealing with the Service Manager who has not actually seen the problem. The mechanic who did witness what happens, and agreed with me that there is a problem, was on vacation last week.

I'm hoping that by writing to you, you can shed some light on what might be the problem. I have spent a fortune on my car and cannot afford to buy another one! I love my little MGF but am afraid that I will have to sell her if the problem goes beyond the 'normal' level of service given by the garage (i.e. do they know about drilling holes 4 equi-spaced 6mm holes in the thermostat ring!!!)...
The Wiz

sounds like air locks in the coolant system, or any other blockage.
Radiator replaced already, though.
Could be a combination with bad coolant sensor connector.

You know about this document collection ?
http://www.mgfcar.de/hgf/index.html
(check all links on site)

btw. The drill of 4 holes in such big size of 6mm will nearly *de-activate* and complete bypass the thermostat. Carl and I think Jon Fredheim did 3mm, 1 off only. But that's another story and doesn't relate to the problem solution.

Regards
Dieter
Dieter K.

Wiz - to me it sounds like the cooling system described is behaving perfectly normal. With the heater valve closed it is only the coolant in the engine's cooling jacket that is heated during the warm-up period - the rather small volume is rapidly heated and a couple of kms driving is all it takes to reach running temp. With the valve open the coolant also circulates through the heater pipes and core, hence the much longer warm-up time. To avoid thermal shocks it is a wise rule to drive with the heater valve slightly open until the engine has reached running temperature. This has the same effect as drilling hole(s) in the thermostat valve.

Cooling trouble may have been the reason why the earlier engine seized but it could also be from a lubriation system failure. Was the engine stripped to check which parts had seized? A piston seizure may be caused by overheating, if it was a crankshaft or conrod bearing it was a lubrication problem.

Dieter - two years and 50.000 has now passed since I changed my HG properly (and fitted the thermostat with the tiny hole in it). I am very pleased to inform that not just the engine but the entire car has served me faultlessly!
Jon

Thanks people. :-)
The Wiz

Wiz, if holes have been drilled in the thermostat _at all_ then this would be why you have very long heat up times. The 4x4 comment sounds like ar*e to me, if they fitted a 1.8k from a landrover then I don't think there is _any_ diffrence between this and the 1.8k from an F.
Will Munns

I agree with Will - the engines should basically be identical between any 16v engines (if the original one was not a VVC, though). Details like oil sump (alloy or pressed steel) may differ but these parts can easily be swapped.
Jon

Mike, sounds like a classical case of the cooling system not having been bleed properly. The system sounds to be air locked (hence poor heater function).

Poor heater function can also be caused by the coolant not reaching the heater box. This is not wholey reliant upon the thermostat function (as there is a bypass circuit from the heater to the expansion tank - but this requires normal operation of the jiggle valve).

Sounds as though the cooling system needs to be thoroughly investigated.
Rob Bell

Thanks again!

It really sounds to me as though this poor person is getting the runaround and some very bad advice. :-(
The Wiz

The cooling system needs to be properly bled and repressurised, a Porsche garage may not appreciate the importance of that with an F. Air locks can lead to yet another HGF.

Point him to this BBS and see if one of the Swiss guys can recommend someone for him to use for servicing - or even Dieter for a neighbouring German garage?
Dot

This thread was discussed between 21/07/2003 and 23/07/2003

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