Just thought I'd toss this one into the ring and see if anyone had any thoughts on it. It possibly is something that should be discussed in General Topics but I think the number of Cits with this problem makes it fairly topical for this forum.
We often have postings from people with a leaking heater matrix and in some cases it is not the first time this has happened to a particular car. It's often discussed why so many have blown & for what reason; common theory is that it is corrosion which whilst this could be the case, it is questionable these days if a proper inhibitor is used which often they claim has been.
I recently had a problem with one on a Ford/Mazda that I own, yet from appearance, it looked OK. As I live in the tropics, I simply by- passed the heater matrix as apart from when we have wet weather (extremely rarely) it is never used.
A few weeks later, I discover the head gasket is on the way out which is pressurising the cooling system excessively. As the vehicle is a "cab over engine" type, it is a fairly inconvenient job to constantly check the water & as it is an extremely hot running motor,it is not viable to lift the seat to check the water during normal driving for those reasons.
My thoughts are, I wonder how many matrix are changed or for that matter split by excessive pressure caused by a leaking head gasket and should the head gasket be tested prior to a matrix being replaced in case the pending gasket failure causes the new matrix to leak.
Anyone got any thoughts or experience on this??
Alan S
A theory on leaking heater matrix
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tomsheppard
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In theory, the overall pressure in the cooling system cannot exceed about 15 PSI so there is little possibility of the matrix bursting that way. To advance the theory, could this be a matter of load reversals (warm up, pressurise, cool down) causing fatigue of the joints? This would tend to be shown if cars that had done high motorway mileages did not fail as often as those used for short trips.
Well, I can toss in my experience, for what it may add.
We have a Peugeot 306, 8 years old, and it has gone through 2 heater matrices. The first was at 2 years, just out of warranty. The second was about a year or so later (on holiday of course!) at the end of a two day, 2900 km drive, for what that may matter.
We live in Perth, Western Australia, with mild winters. The car is used predominantly for urban trips, the majority of which would be commuting - my wife does about 10-11 km each way.
The current matrix is now about 5 years old. Driving history for the past 5 years has been more or less identical to the previous periods when the heater elements failed. Coolant has been changed on time with the Peugeot fluid used.
No head gasket trouble. In fact no other trouble at all.
I agree that the number and intensity of temperature cycles (expand-contract cycles, you might as well say) will be less, the warmer the climate and the longer the average trip. Could be that they simply fatigue, with QA in manufacturing and individual car coolant management accounting for the variable lifetimes.
My older cars have cycled far more times, one with an aluminium heater (the Renault 16) and have never failed. They also have water valves, so the heater itself is isolated from many of the cycles.
There's not much response from Peugeot-Citroen (apart from being supportive and contributing to out of warranty repair costs, for which I am grateful).
So I doubt it's head gasket initiated. I suspect the things simply aren't robust enough, coupled with being about the hardest single component to get at on the car. I reckon making them out of brass, copper and solder would be a great step forward, coupled with making access a whole lot better. A removable plate on the firewall wouldn't be a bad start!!! Wouldn't matter if it had 25 bolts if that's what it would take to make it all strong enough.
Years ago, my fathers Datsun Pulsar did the same thing, and it cost him quite a bit to fix. So it isn't just PSA vehicles of the recent types.
JohnW
We have a Peugeot 306, 8 years old, and it has gone through 2 heater matrices. The first was at 2 years, just out of warranty. The second was about a year or so later (on holiday of course!) at the end of a two day, 2900 km drive, for what that may matter.
We live in Perth, Western Australia, with mild winters. The car is used predominantly for urban trips, the majority of which would be commuting - my wife does about 10-11 km each way.
The current matrix is now about 5 years old. Driving history for the past 5 years has been more or less identical to the previous periods when the heater elements failed. Coolant has been changed on time with the Peugeot fluid used.
No head gasket trouble. In fact no other trouble at all.
I agree that the number and intensity of temperature cycles (expand-contract cycles, you might as well say) will be less, the warmer the climate and the longer the average trip. Could be that they simply fatigue, with QA in manufacturing and individual car coolant management accounting for the variable lifetimes.
My older cars have cycled far more times, one with an aluminium heater (the Renault 16) and have never failed. They also have water valves, so the heater itself is isolated from many of the cycles.
There's not much response from Peugeot-Citroen (apart from being supportive and contributing to out of warranty repair costs, for which I am grateful).
So I doubt it's head gasket initiated. I suspect the things simply aren't robust enough, coupled with being about the hardest single component to get at on the car. I reckon making them out of brass, copper and solder would be a great step forward, coupled with making access a whole lot better. A removable plate on the firewall wouldn't be a bad start!!! Wouldn't matter if it had 25 bolts if that's what it would take to make it all strong enough.
Years ago, my fathers Datsun Pulsar did the same thing, and it cost him quite a bit to fix. So it isn't just PSA vehicles of the recent types.
JohnW
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Jon
Well Mr S, you might say that you have opened a can of worms here.
We've had past discussions on this forum about the premature failure of matrixes on ZX, 306, XM and the like, and this "problem" has also been aired on other motoring sites.
The situation is that the original factory fit Matrix (maybe in conjunction with the factory fit coolant) seems to last a long time, then fails. Car owner fits, or has fitted a replacement matrix. If you're in the UK, then that matrix will be Genuine Citroen (Valeo in their box), or from someone like us (Valeo in Valeo box).Some short while later then this Genuine matrix starts leaking.
The matrix is then returned to the manufacturer, Valeo, for a warranty and quite likely a labour claim too in view of the time a typical Cit matrix takes to replace. That claim is invariably rejected I find.
The reason for rejection used to be that the "wrong" antifreeze ie not Citroen Antigel was used, causing premature corrosion of the matrix.
Recently, the rejection has taken the form that unless ALL old coolant (including draining the block) is removed, then system must then be flushed with Forte Cooling system flush, then refilled with Antigel diluted to the correct level; then unless all this is done then the warranty won't stand. Doh.
There have been several theories about all of this floating around in the Trade, or on-line. One person (on the subject of the notorious XM matrix) even suggested earthing the matrix, believing that the premature failure was the result of electrolisis.....
Certainly its "interesting" that the original matrix can last say 100 k miles, and yet its replacement manages less than 5k.
Valeo may well have a point ref the use of Cit Antigel, I certainly use the stuff myself, replace coolant every year or so, and have never actually had to fit a matrix to a ZX in 3 cars and about 120k driven miles between the three of them (touch wood) <img src=icon_smile_wink.gif border=0 align=middle> The corrosion inhibitors in Antigel are certainly designed for the classic Cit alloy head and steel block found on most engines.Its also interesting to note that in France, matrix failures seem less common, and my own theory is that soft water without added flouride may help in the native country.
Lastly, Alan makes a very interesting point with regards to pressurisation of the cooling system causing failure of the matrix. I certainly agree that the relatively thin matrix must be a weak point in the system when combustion gasses enter the cooling system.
I dealt with a disgruntled Trade customer a couple of years ago who had fitted 3 matrixes to a ZX and they had all failed. Both Valeo Tech and myself found this a bit hard to believe. It was suggested that the car was pressure checked and tested, and surprise, the head gasket was shot, forcing gasses into the coolent.Needless to say.....
Jon Wood
forum@andyspares.com
We've had past discussions on this forum about the premature failure of matrixes on ZX, 306, XM and the like, and this "problem" has also been aired on other motoring sites.
The situation is that the original factory fit Matrix (maybe in conjunction with the factory fit coolant) seems to last a long time, then fails. Car owner fits, or has fitted a replacement matrix. If you're in the UK, then that matrix will be Genuine Citroen (Valeo in their box), or from someone like us (Valeo in Valeo box).Some short while later then this Genuine matrix starts leaking.
The matrix is then returned to the manufacturer, Valeo, for a warranty and quite likely a labour claim too in view of the time a typical Cit matrix takes to replace. That claim is invariably rejected I find.
The reason for rejection used to be that the "wrong" antifreeze ie not Citroen Antigel was used, causing premature corrosion of the matrix.
Recently, the rejection has taken the form that unless ALL old coolant (including draining the block) is removed, then system must then be flushed with Forte Cooling system flush, then refilled with Antigel diluted to the correct level; then unless all this is done then the warranty won't stand. Doh.
There have been several theories about all of this floating around in the Trade, or on-line. One person (on the subject of the notorious XM matrix) even suggested earthing the matrix, believing that the premature failure was the result of electrolisis.....
Certainly its "interesting" that the original matrix can last say 100 k miles, and yet its replacement manages less than 5k.
Valeo may well have a point ref the use of Cit Antigel, I certainly use the stuff myself, replace coolant every year or so, and have never actually had to fit a matrix to a ZX in 3 cars and about 120k driven miles between the three of them (touch wood) <img src=icon_smile_wink.gif border=0 align=middle> The corrosion inhibitors in Antigel are certainly designed for the classic Cit alloy head and steel block found on most engines.Its also interesting to note that in France, matrix failures seem less common, and my own theory is that soft water without added flouride may help in the native country.
Lastly, Alan makes a very interesting point with regards to pressurisation of the cooling system causing failure of the matrix. I certainly agree that the relatively thin matrix must be a weak point in the system when combustion gasses enter the cooling system.
I dealt with a disgruntled Trade customer a couple of years ago who had fitted 3 matrixes to a ZX and they had all failed. Both Valeo Tech and myself found this a bit hard to believe. It was suggested that the car was pressure checked and tested, and surprise, the head gasket was shot, forcing gasses into the coolent.Needless to say.....
Jon Wood
forum@andyspares.com
Before I learned not to go anywhere near Citroen garages, I took my CX to one to investigate a coolant loss problem. They pressure tested the system, allegedly finding a split hose. Two weeks later the matrix began leaking. Citroen denied responsibility, charged the earth to replace the matrix, and made a pig's ear of the job. If human taxidermy were legal in this country, I would recommend it for all Citroen UK employees.
I think this is a subject we could come up with a thousand theories on & still be wrong, but my thoughts were that if air gets into any part of the system, particularly a dead end such as a high point on a matrix, & it will create a vapour lock or steam lock which can create extremely high pressures. In my case, I suspect this was the case even though my car is Jap & doesn't have the air bleeders etc. When fairly warm, the steam releasing from the rear heater matrix could be heard; it sounded like a train going through a station & I'll defy anyone to refit the radiator cap once this pressure was heard being released! As regards differeing pressures in different parts of the engine, I recently had an intake hose to the pump on my BX 16V leak, but only when the engine was stopped. The reason? It was on the intake side; had it been on the outlet side it would have been like driving with a fountain under the bonnet which is why I suspect forces a bit more complicated than just the cap pressure.
The theory of the earth strap on the XM matrix I feel *may* (?) have been counterproductive although no doubts greater scientific minds than mine may explain it more articulately. The reason I suspect that this could be either ineffective or work in reverse to what was anticipated is that many years ago over here, we were having big problems with electrolysis in refrigerators due to the variety of metals used.
One company with sophisticated equipment did a test on one of their fridges & found they had 39 volts of static electricity passing through the fridges system within 72 hours of it being turned off at the power point. It would still have been earthed.
In contrast, due to the high salt content in the air in Australian Coastal towns, I understand solar hot water systems (in particular) as well as electric ones are fitted with what is called a "sacrificial anode" which I understand is a block of pure aluminium emersed in the water so that it will attract the corrosion to it rather than to the system which to my little brain produces another set of problems; Wouldn't this then cause greater corrosion to the brass & copper parts?
I think the load reversals theory has merit but would it expand/contract far enough to cause metal fatigue? Could it be a number of the above factors in combination?
Another point also is, if they can produce "reverse cycle" air/con for shops & houses then why not for cars, & scrub the heater matrix altogether??
That's an intersting one for the inventors now isn't it?
Alan S
The theory of the earth strap on the XM matrix I feel *may* (?) have been counterproductive although no doubts greater scientific minds than mine may explain it more articulately. The reason I suspect that this could be either ineffective or work in reverse to what was anticipated is that many years ago over here, we were having big problems with electrolysis in refrigerators due to the variety of metals used.
One company with sophisticated equipment did a test on one of their fridges & found they had 39 volts of static electricity passing through the fridges system within 72 hours of it being turned off at the power point. It would still have been earthed.
In contrast, due to the high salt content in the air in Australian Coastal towns, I understand solar hot water systems (in particular) as well as electric ones are fitted with what is called a "sacrificial anode" which I understand is a block of pure aluminium emersed in the water so that it will attract the corrosion to it rather than to the system which to my little brain produces another set of problems; Wouldn't this then cause greater corrosion to the brass & copper parts?
I think the load reversals theory has merit but would it expand/contract far enough to cause metal fatigue? Could it be a number of the above factors in combination?
Another point also is, if they can produce "reverse cycle" air/con for shops & houses then why not for cars, & scrub the heater matrix altogether??
That's an intersting one for the inventors now isn't it?
Alan S
My xm 2.1td blew its head gasket and the resulting extra pressure in the cooling system was enough to blow the heater matrix. I can only agree with the suggestion that the problem is more likely to be dodgy head gasket related than dodgy heater matrixes.(Is that the plural of matrix or is it matri?)
My car had done around 140,000 miles so the matrix had had a lot of heating and cooling, pressurising and depressurising but was fine until the head gasket problem came along.
Maybe they lose a bit of strength over the years - they are only aluminium and plastic pressed together.
My car had done around 140,000 miles so the matrix had had a lot of heating and cooling, pressurising and depressurising but was fine until the head gasket problem came along.
Maybe they lose a bit of strength over the years - they are only aluminium and plastic pressed together.
<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
Maybe they lose a bit of strength over the years - they are only aluminium and plastic pressed together.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Well exactly!!!! Pity they're so damn hard to get at when the apparently inevitable happens.
JohnW
Maybe they lose a bit of strength over the years - they are only aluminium and plastic pressed together.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Well exactly!!!! Pity they're so damn hard to get at when the apparently inevitable happens.
JohnW
Alan,
I'm with you there. Reverse cycle AC is just what we need! Drive it electrically and go to 32 volts or whatever voltage the new system that is coming uses.
Perth is almost mild enough to just bypass the stupid thing altogether if it fails again. But only almost. Then I mentioned somewhere else that I was sore tempted to get a "traditional" one made of brass and copper with the same dimensions. When I looked from the engine side of the firewall, the thought of cutting a hole loomed large too!
The earthing aspect is interesting. I'd have thought if there were really a problem here there would be many, many more failures than are current. All metals have an electrochemical potential that causes corrosion if they are connected and also immersed in a conductive fluid, hence the use of zinc sacrificial anodes in boats and odd things. One of the main aspects of all fancy coolants, as far as I know, is the use of distilled or demineralised water which has very low electrical conductivity and hence allows only low rates of chemical reaction between the different metals. I ran my Renault 750 in Adelaide on neat rainwater for many years with pretty well no corrosion, and then the minor corrosion of alloy on the radiator hose fittings was protecting something else! I agree with you that I'd stay away from connecting bits with straps in case the opposite happened - if you apply a voltage you can reverse the natural condition.
Enough from me on this one. But it irritates me that this combination of dubious engineering and dismal accessibility is still there on these cars, especially as they are so good in most other ways. The middle of the Nullarbor is no place for one of these matrices to fail!
JohnW
I'm with you there. Reverse cycle AC is just what we need! Drive it electrically and go to 32 volts or whatever voltage the new system that is coming uses.
Perth is almost mild enough to just bypass the stupid thing altogether if it fails again. But only almost. Then I mentioned somewhere else that I was sore tempted to get a "traditional" one made of brass and copper with the same dimensions. When I looked from the engine side of the firewall, the thought of cutting a hole loomed large too!
The earthing aspect is interesting. I'd have thought if there were really a problem here there would be many, many more failures than are current. All metals have an electrochemical potential that causes corrosion if they are connected and also immersed in a conductive fluid, hence the use of zinc sacrificial anodes in boats and odd things. One of the main aspects of all fancy coolants, as far as I know, is the use of distilled or demineralised water which has very low electrical conductivity and hence allows only low rates of chemical reaction between the different metals. I ran my Renault 750 in Adelaide on neat rainwater for many years with pretty well no corrosion, and then the minor corrosion of alloy on the radiator hose fittings was protecting something else! I agree with you that I'd stay away from connecting bits with straps in case the opposite happened - if you apply a voltage you can reverse the natural condition.
Enough from me on this one. But it irritates me that this combination of dubious engineering and dismal accessibility is still there on these cars, especially as they are so good in most other ways. The middle of the Nullarbor is no place for one of these matrices to fail!
JohnW
<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
Maybe they lose a bit of strength over the years - they are only aluminium and plastic pressed together.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Well exactly!!!! Pity they're so damn hard to get at when the apparently inevitable happens.
JohnW
Maybe they lose a bit of strength over the years - they are only aluminium and plastic pressed together.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Well exactly!!!! Pity they're so damn hard to get at when the apparently inevitable happens.
JohnW
[quote/]
"I'm with you there. Reverse cycle AC is just what we need! Drive it electrically and go to 32 volts or whatever voltage the new system that is coming uses."
John,
This is the mystifying part; all it would really need is a solenoid valve to redirect the gas flow whilst still driving the compression from the cars engine. The only snag I could see would have to be getting some heat in the general direction of the condensor which would ice up in European winter conditions, but if they can put a man on the moon, I've no doubts they could redirect air via ducts from the engine area or radiator. Who knows, on a Citroen, the man on the moon may be the easier option <img src=icon_smile_big.gif border=0 align=middle> <img src=icon_smile_big.gif border=0 align=middle>
Alan S
"I'm with you there. Reverse cycle AC is just what we need! Drive it electrically and go to 32 volts or whatever voltage the new system that is coming uses."
John,
This is the mystifying part; all it would really need is a solenoid valve to redirect the gas flow whilst still driving the compression from the cars engine. The only snag I could see would have to be getting some heat in the general direction of the condensor which would ice up in European winter conditions, but if they can put a man on the moon, I've no doubts they could redirect air via ducts from the engine area or radiator. Who knows, on a Citroen, the man on the moon may be the easier option <img src=icon_smile_big.gif border=0 align=middle> <img src=icon_smile_big.gif border=0 align=middle>
Alan S
The only snag I could see would have to be getting some heat in the general direction of the condensor which would ice up in European winter conditions, but if they can put a man on the moon, I've no doubts they could redirect air via ducts from the engine area or radiator.
Alan,
Exactly. A condensor that had dual pipes with AC refrigerant and coolant in intimate contact, i.e. integrate radiator and condensor, and you'd be there wouldn't you. Doesn't sound earth shatteringly difficult but I'm a geologist not an automotive engineer! I must write to Renault's innovation magazine.
John
[/quote]
Alan,
Exactly. A condensor that had dual pipes with AC refrigerant and coolant in intimate contact, i.e. integrate radiator and condensor, and you'd be there wouldn't you. Doesn't sound earth shatteringly difficult but I'm a geologist not an automotive engineer! I must write to Renault's innovation magazine.
John
[/quote]