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MGTF 135
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Discussion Starter #1
Two days ago my header tank warning light took ages to go off, I didn’t think anything about it because I was in a hurry. Yesterday, the light wouldn’t go off at all so I turned off the engine and had a look, (good job I fitted the updated header tank and cap last year as I have the later dash with the small rad warning light).

Horror of horrors, water level right down, about 2cm left in the header tank, must be HGF, the car has done 58K Km. I did the usual, checked the oil – nice and black – hmm good job I ordered new oil over the Christmas period. Very, very slight oily film on the top of the header tank water (well, not really a film), but it looked the same as it did in my old TF.

My neighbour watched me sniffing the header tank and thought I’d found a new way of ingesting herbs, but nothing concrete came to my mind, so what happened?

I pondered this for a while – as you do at my age – and then it came to me. Last week at some time, I was being a boy racer, and suddenly there was this brief but unmistakable smell of escaping steam (you know the smell) – no sound, just the smell. It didn’t last, and I was too busy driving fast to give it another thought except “oh, the heater valve has opened”, a stupid thought because the heater was on anyway.

I am guessing / hoping that the cap vented for some reason – failed, or whatever, so I topped up the coolant and put on the cap from the old tank nice and tight. Yes, I ordered a new cap “MG original” in the MG plastic bag which should be with me sometime next week.

Took her out for a spin today and the water level hasn’t gone down, so I’m crossing my fingers that the cap was the problem.

But of course it could be the start of HGF, under-car cooling pipes, radiator, a split hose somewhere, heater matrix, inlet manifold, water pump, to name just a few, time will tell.
 

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In the Garage
MG TF
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It does sound more like a leak than a HGF, as the level was so low I would be inclined to bleed the system just in case any air has been sucked into the system.
 

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I think you are being a bit hasty deciding it is HGF before having a good look around at the cooling system and radiator. As well as new rad cap (good thinking) have a look below the inlet manifold and water pump for coolant stains, and monitor closely for a few weeks.
 

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1995 MGF Mpi
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737 Posts
I second the thought of it being the inlet manifold gasket, have had this gasket fail on both of our Fs.

One thing I would suggest is the addition of coolant dye to the coolant. This makes the leaking coolant glow bright when hit with a black light. It made it a lot easier for me to find coolant leaks.
 

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MGTF 135
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Discussion Starter #7
So, thanks to all of you. I did buy the coolant dye and light on fleabay but it looks like I don't need it - this time. Since I changed over the expansion tank cap, the water level hasn't moved. Thank goodness, but I'll still keep an eye on it - just in case.
 

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MGTF 135
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Discussion Starter #10 (Edited)
Oh dear, I spoke too soon, The problem has started again. The system is still pressurised after standing for a couple of hours, but I'm loosing water again - if the system is holding pressure how am I loosing water?. I'll try using the Ring leak detector fluid now but I still think the may be the start of HGF. I did fit a new cap to the bottle, but it seemed to be OK with second hand spare cap I fitted, maybe the new one was faulty, but it is holding pressure, so it's nearly a litre lost in 2 weeks - about 250 km around 20km a day. My garage and drive are on a slope, so no possibility to do this myself, and I don't know any mechanic who knows anything about our cars. Anyone know an MG mechanic who fancies a trip to the Czech Republic?

UPDATE:
I'm going to try this combustion leak detector before any invasive surgery on the car: COMBUSTION LEAK TESTER KIT CO2 PETROL HEAD GASKET TEST FLUID BLOCK 50 TESTS | eBay
 

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'06 MG ZR +120 (HQM) '04 MG ZR 105 (IAB)
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If the system remains pressurised even after cooling off completely, it would suggest that there is a head gasket failure past one or more of the fire rings of the gasket. It is not an uncommon form of HGF, and can be the result of the liners being low (ie. not enough stand proud to firmly trap the fire rings between head and block), or can be as a result of overheating (often very localised, and therefore not displaying outward symptoms of overheating) which causes the head face to soften allowing the fire rings to dig in and become 'loose'.

If the gasket has failed at the fire rings, you will be losing coolant because it may be sucked into the cylinder past the fire rings on the induction stroke, and burned off on the ignition stroke and exit via the exhaust system. There is unlikely to be a large enough quantity at any one time for it to be apparent in the exhaust output as excessive vapour. Coolant may also seep into the affected cylinder(s) due to the residual pressure in the system after the engine is stopped. In this case, you may sometimes find that there is a slight initial misfire when you first start the engine after it has stood for a while/overnight as it dries out the affected cylinder (the same sort of symptoms that apply when the inlet manifold gasket has failed).

The block test may or may not be helpful - the best way to diagnose such a failure is by having a 'sniff' test done using an exhaust gas analyser (such as is used for the MOT emissions test) which will confirm if there are excessive exhaust gases in the expansion tank. Note: there are always some traces of exhaust gases in the coolant and expansion tank, so these tests will only confirm when there is an excessive amount and the gasket has definitely failed. Just because they do not return a significant positive result, it cannot always be assumed that the gasket is therefore OK ;)

If confirmed, the head face may be indented by the fire rings (and will need a skim to level the surface again, and possibly hardness testing too, to ensure that the skimmed surface will resist fresh indentation), or the liners may be too low (they seem to have been below spec from the factory in quite a lot of cases). Low liners can be removed and successfully shimmed up to the correct amount of stand proud using shims which are available for the purpose and obtainable from any XPart/MG Rover parts retailer.
 

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MGTF 135
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Discussion Starter #12
Thanks Man in the car for your professional input, this sounds very complicated as I've never had this problem with a TF and finding a mechanic to help me is going to be near impossible here. Gloom and doom day for my lovely car.
 

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'06 MG ZR +120 (HQM) '04 MG ZR 105 (IAB)
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Hardly 'professional' - I have learned pretty much everything that I know about these engines from reading this forum (and others) over the last 16 years. The K series is actually a very easy engine to work on, and any half decent trained mechanic or even competent DIY mechanic should be capable of doing what is needed.

It more a case of making sure that the job is done right - too many mechanics who don't know of the K series little foibles simply whip the head of and bang a new head gasket in without checking things like liner heights and looking for signs of what has caused the failure in the first place, and lo and behold the new gasket fails within a short time.

There are a number of issues with the K, which there is not space to relate here (Des Hamill wrote a whole book about them!), but provided the cylinder liners stand proud of the block (ideally by around 3 thou), are all of even stand proud, the head face is flat and 'true' and the long bolts are not stretched beyond tolerance, and the coolant system is checked for leaks and refilled correctly to avoid air locks, a successful repair should last and last (I did my own head gasket change on my ZR using the SAIC 6-layer MLS gasket and it has been 6 years and nearly 55000 miles and the system still never needs topping up between the 5 year coolant changes).

One thing which it is very beneficial to do whilst the head is off is to take a mini-drill with a grinder/burr attachment to the ports into the water passages in the head and remove the excess cast material to enlarge them - this can significantly improve coolant flow into the head, lack of which is often implicated in the localised overheating that leads to damage to the elastomer beading of the factory fit head gasket, head softening, fire ring indentation and subsequent HGF.

None of the repair/modification procedures are beyond the capabilities of anyone with some mechanical ability/desire and willing to have a go (and having access to the tools, obviously!).

As far as finding a MG Rover experienced mechanic, I know that certain of the MG Rover specialist mobile mechanics do travel abroad to do work on occasion, but whether that would include traveling as far as you I don't know? In do know Jon Norris (Rough Luck Racing) has been as far as Portugal and Norway to repair MGs, so might be worth a try? (or perhaps a bit expensive?).
 

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MGTF 135
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Discussion Starter #14
Once again thanks MITC, funnily enough, I did look at the Rough Luck Racing website today and just wondered about them. I can test the water and offer a working holiday here. There's a lot of interesting folkelore goes on here, I can only ask. I have rebuilt engines before, so mechanically it's not beyond me, but physically it may be these days. I'm also going to have a look to see if there are any travelling mechanics in Austria - Vienna is about 250 km, but Austria is very expensive, but closer than Prague to where I live, or maybe even Poland, that's not so far either. I can keep my eye on the bottle and top up if needs be until I get the C02 tester, if that's positive, then I'll go to a good garage and get them to double check. Garages here are very expensive if you aren't Czech - cost me 550 quid (nearly a month's wages) for a small sill repair (jack slipped), no rust just a small dent. They look at the car - "exotic foreign car means exotic prices (think BMW the rich businessman's choice here)" which is why I do most of the stuff myself. So, about a week to get the kit and then I should know one way or another how to proceed.
 

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1995 MGF Mpi
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Is the coolant dye not showing a leak? Have you checked for a leak under the exhaust manifold or at the timing belt end of the inlet manifold? Are you seeing any 'mayonnaise' under the cap of the expansion cap or the oil fill cap on the engine?

MITC is absolutely right about opening up the coolant passes in the head. I found these passages to be almost covered over with casting material.

Changing a head gasket is far from difficult, I've done it, but I can understand your trepidation if you do not have a proper place to undertake the work.
 

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Discussion Starter #16
Hi mowog73, I haven't done the leak check with the dye, I thought I would do the CO2 test first, then add the dye in case the dye upset the CO2 test. No 'mayonnaise' anywhere. If it was the summer I would think again about doing it myself but it's damn cold here at the moment and will get colder in the next few weeks. As I wrote before, I will do the CO2 test first (I sniffed the tank but I just smelt hot water). Then add the dye and search with the UV lamp, but that will be next week. It's a good job that I don't have to use the car except on Tusdays.
 

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Discussion Starter #17
Latest update: I did the CO2 check (engine was hot) with the little C02 tester. It bubbled nicely (took it up to up to 3000 rpm, about 5 minutes) and didn't change colour (so hopefully no CO2), touch wood gasket isn't leaking. I'm thinking there was an airlock - maybe in the heater - I only put the heater on max about a month ago, and the airlock cleared and lowered the water level, or it was just a faulty cap. The water level has stayed constant for weeks now.
 
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