MGZS 1.8 over heating – HG failure or something else
Discussion
A friend at work has a 2004 MGZS with a 1.8 k series engine. Last year she asked me to take a quick look as the car was over heating when she drove to work. I went to take a quick look and she had lost some coolant so we topped it up. We ran the car at idle for about 10 minutes and it did not overheat. My first thought has HG failure so I looked under the oil cap for mayo and check the oil level to see if there was any water mixed in. There was no mayo but the oil level was very low so we topped that up.
I checked that the radiator hoses were warm and that water was flowing round the radiator which it was. I told her to go and get the engine flushed and have an oil change and to change and flush the coolant which she did in December last year. Since then she has had no problems and the coolant light that had been on and off for the past year finally went out. All good I thought.
Yesterday I enquired if she had checked the oil level as it has been over a month. She hadn’t but said she would. Then last night the temperature gauge went up to the red whilst she was driving home. She topped up with water and this morning it was ok again so my thoughts are that water must be escaping somewhere. There is no sign of a leak from any hoses but could the radiator cap be letting steam out when under pressure or the expansion bottle? If it is HG failure are there any tests she can do to check. I suggested using some rad weld in the water as that would seal and small holes that might be allowing water loss, has anyone got any recommendations for the best stuff or just ideas of what problems are most common with this car/engine.
I checked that the radiator hoses were warm and that water was flowing round the radiator which it was. I told her to go and get the engine flushed and have an oil change and to change and flush the coolant which she did in December last year. Since then she has had no problems and the coolant light that had been on and off for the past year finally went out. All good I thought.
Yesterday I enquired if she had checked the oil level as it has been over a month. She hadn’t but said she would. Then last night the temperature gauge went up to the red whilst she was driving home. She topped up with water and this morning it was ok again so my thoughts are that water must be escaping somewhere. There is no sign of a leak from any hoses but could the radiator cap be letting steam out when under pressure or the expansion bottle? If it is HG failure are there any tests she can do to check. I suggested using some rad weld in the water as that would seal and small holes that might be allowing water loss, has anyone got any recommendations for the best stuff or just ideas of what problems are most common with this car/engine.
The only really common failure with the engine is the head gasket, so I'd say that's most likely. It's quite possible that it wasn't the original problem, but went as a result of the engine being driven hot due to low coolant and/or oil before. A hose can go on any engine, but I'd imagine you'd notice it.
I suppose the water pump might be on the way out?
I suppose the water pump might be on the way out?
kambites said:
The only really common failure with the engine is the head gasket, so I'd say that's most likely. It's quite possible that it wasn't the original problem, but went as a result of the engine being driven hot due to low coolant and/or oil before. A hose can go on any engine, but I'd imagine you'd notice it.
I suppose the water pump might be on the way out?
No no no no it isn't! Infact there are 2 major issues that generally contribute to HG faliure.I suppose the water pump might be on the way out?
IMG gaskets can fail and waterpumps are prone to going as well. Both will result in HG failure if left untreated.
SebastienClement said:
No no no no it isn't! Infact there are 2 major issues that generally contribute to HG faliure.
IMG gaskets can fail and waterpumps are prone to going as well. Both will result in HG failure if left untreated.
Any water pump can fail, but I've not seen a significantly higher incidence of this on the K-series than anything else? I've never even heard of the intake manifold gasket going on the K. IMG gaskets can fail and waterpumps are prone to going as well. Both will result in HG failure if left untreated.
In my experience, almost all head gasket failures are caused by either people abusing the engine from cold, or running it without enough coolant (due to a variety of other failures, but no one common one).
kambites said:
Any water pump can fail, but I've not seen a significantly higher incidence of this on the K-series than anything else? I've never even heard of the intake manifold gasket going on the K.
Both are well documented issues. Original waterpumps have weak innards are are prone to breaking up.IMG gaskets can give VERY similar symptoms to HG faliure.
MGjohn has written at length about both these issues on PH.
SebastienClement said:
kambites said:
Any water pump can fail, but I've not seen a significantly higher incidence of this on the K-series than anything else? I've never even heard of the intake manifold gasket going on the K.
Both are well documented issues. Original waterpumps have weak innards are are prone to breaking up.The service schedule says to replace it with the cam-belt doesn't it, so it's not as if it's going to get old?
ETA: Mind you, I've just remembered that the cam belt change interval specified by Lotus was lower than other uses of the engine, so maybe that's why it doesn't go on Elises?
Edited by kambites on Thursday 24th January 11:10
kambites said:
Strange, I've never even heard of it going.
The service schedule says to replace it with the cam-belt doesn't it, so it's not as if it's going to get old?
The accepted advice over on the mg-rover.org and the75andztclub are that it should be changed for an updated pump with metal impellers. Seriously, MGJohn is a wealth of information and it's all here on PH.The service schedule says to replace it with the cam-belt doesn't it, so it's not as if it's going to get old?
SebastienClement said:
The accepted advice over on the mg-rover.org and the75andztclub are that it should be changed for an updated pump with metal impellers. Seriously, MGJohn is a wealth of information and it's all here on PH.
Mine gets changed every four years anyway, so I'm not overly worried about it. 
SebastienClement said:
kambites said:
Mine gets changed every four years anyway, so I'm not overly worried about it.
Likewise, but it's definitely something for the OP to keep in mind!kambites said:
Any water pump can fail, but I've not seen a significantly higher incidence of this on the K-series than anything else? I've never even heard of the intake manifold gasket going on the K.
I cutout a cereal box to make an intake manifold gasket on mine 
kambites said:
In my experience, almost all head gasket failures are caused by either people abusing the engine from cold, or running it without enough coolant (due to a variety of other failures, but no one common one).
I don't believe this for one second. The HGs fail because they are of a poor design. All cars are abused from cold by normal drivers and they seem to cope fine with it.kambites said:
I guess so, if the car hasn't been looked after properly. Or was it not part of the standard servicing on MG/Rover installations?
No, I believe it's been found out rather by trial and error. I don't believe it was specified by MG Rover.Incidentally apparently one of the biggest causes of the waterpump leaking is the strength of the coolant changing.
StottyZr said:
I don't believe this for one second. The HGs fail because they are of a poor design. All cars are abused from cold by normal drivers and they seem to cope fine with it.
Where did I say that wasn't the case? The engine is clearly flawed, but that doesn't change that fact that it's reasonably reliable if looked after properly (although they can still go). That's one of the primary reasons that things like Elises and Caterhams have a much lower incidence rate of the failure - owners tend to be meticulous about how they look after their engines. It's also probably the primary reason that Freelanders fair so badly - it's difficult not to thrash an engine when you're trying to use a 120bhp N/A four pot to move a small moon.
Edited by kambites on Thursday 24th January 11:19
Sticky thermostat is my vote if its internittent. If a headgasket blows, its blown and tends not to heal up.
I would swap thermostat and then use Liquid Glass.
A mate of mine often has problems with the K series engine and uses it. He's never had a comeback.
I used it on a car ages ago. It worked a treat. Worth a shot.
http://www.google.co.uk/products/catalog?q=liquid+...
http://www.ehow.co.uk/how_7665901_use-glass-coolin...
I would swap thermostat and then use Liquid Glass.
A mate of mine often has problems with the K series engine and uses it. He's never had a comeback.
I used it on a car ages ago. It worked a treat. Worth a shot.
http://www.google.co.uk/products/catalog?q=liquid+...
http://www.ehow.co.uk/how_7665901_use-glass-coolin...
doogz said:
Also, given how cold it is outside, replacing all the lost coolant with water isn't the greatest idea.
Equally, if it's running hot it's not a good idea either - Ethyl glycol is an anti-boiling agent too.OP. Some things to check:
1) That the expansion tank cap is properly set and that there are no leak paths on it as when you pressurise the system you raise the boiling point significantly (for 50/50 water-glycol you raise from 108C @ atmospheric pressure to ~125C @ 145kPa gauge)
2) Is the degas hose clear? You might have an airlock in the system
3) Any potential leaks in the heater circuit?
4) Any leaks from the radiator? You mentioned the hoses
5) Is there anything blocking airflow to the rad?
6) Check the thermostat functioning - do both rad hoses get hot after EVERY decent journey?
That's the first things to check.
I have just had this problem on the wifes 1.8 freelander (same engine)
Replaced the expansion bottle cap and the inlet manifold gasket (£9) and
voila, jobs a good un.
http://forums.lr4x4.com/index.php?showtopic=57422
Replaced the expansion bottle cap and the inlet manifold gasket (£9) and
voila, jobs a good un.
http://forums.lr4x4.com/index.php?showtopic=57422
kambites said:
StottyZr said:
I don't believe this for one second. The HGs fail because they are of a poor design. All cars are abused from cold by normal drivers and they seem to cope fine with it.
Where did I say that wasn't the case? The engine is clearly flawed, but that doesn't change that fact that it's reasonably reliable if looked after properly (although they can still go). That's one of the primary reasons that things like Elises and Caterhams have a much lower incidence rate of the failure - owners tend to be meticulous about how they look after their engines. It's also probably the primary reason that Freelanders fair so badly - it's difficult not to thrash an engine when you're trying to use a 120bhp N/A four pot to move a small moon.
Edited by kambites on Thursday 24th January 11:19
I always presumed Elise' and Caterhams faired better as they cover low mileage in comparisson, the engines are less stressed and the owners proactively change the HG on them.
As you'll be well aware a pump, skim and gasket change isn't an expensive job on an Mg Zs
I don't know of anyone who has done it proactively unless they're having other upgrades done at the same time. My Elise's gasket went (although not in a big way, it was still perfectly drivable) despite extremely careful treatment. Repairing it only added about 100 quid to the cost of getting the belts done, which were pretty much due anyway. That's why I don't understand people's paranoia about the K-series head gasket on things as valuable as the Elise - I could replace my head gasket every year for the cost of the extra fuel to run anything else of similar performance (including a Toyota engined Elise).
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