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Old 2nd April 2010, 17:51   #11
markb63
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not sure about the pollen filter , have just checked the service history and last time it was changed was over 3 yrs ago .
would this affect the heating ?

will check the sensor tomorrow
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Old 3rd April 2010, 20:05   #12
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Originally Posted by markb63 View Post
not sure about the pollen filter , have just checked the service history and last time it was changed was over 3 yrs ago .
would this affect the heating ?

will check the sensor tomorrow
it will affect the air flow through the heater if it is blocked.
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Last edited by bl52krz; 3rd April 2010 at 20:07.. Reason: try the heater on the recirculating button.if more air,then pollen filter blocked.
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Old 4th April 2010, 05:46   #13
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Firstly if problems with heaters, always first check and see if you have enough water in the system. But you seem to have done that, so let's go to the next issues!
There are times where the cooling from the heater alone is more than what the engine needs to keep cool. This happens especially in cold wet weather, where the windchill factor is high. The natural cooling of the engine from the air flowing around it is high, and the heater inside the car is on maximum.
The thermostat in this case does not come into the picture, because it stays closed, and all the cooling happens via the natural cooling and via the heater which bypasses the thermostat. IOW the hot water to the heater is taken from the cooling system from an outlet that is not controlled, and therefore always fully open.
Note that if you use your demister, you heater works on maximum, even if not "switched on". In that case the system cools the air with AC to maximise moisture extraction, and heats it maximum to increase moisture absorbtion from the front screen.
If the heater does not come up to temperature, try and switch it off. Switch the fan off, and let the engine heat up. Switch the recirculation on. In this case you have minimized the cooling. (it is unknown to me if there is inded a valve, as in older cars, which will open/block the flow through the heater matrix, I some how have a feeling there is not) The temperature of the engine should increasse. You can then switch the heater on partly and keep some heat coming out. If you switch it on fully, again you will cool the engine down, so it is a balancing act. Too much and it gets a lot but cold, less and it gets warm.
There seems to be a lot of this around and one reason is undoubtedly the cold winter.
If this is your problem, you will typically find that the heater works when the engine is labouring hard at low road speed. The worst situation is high speed, low load, like a decline on a highway.
Contributing factors can be mechanical faults and there has indeed been som write ups on these. As so often before, many people do not bring up the conclusion, if there was indeed any, as in the tread below:
http://www.the75andztclub.co.uk/foru...ht=heater+flap
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Old 4th April 2010, 10:47   #14
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hi , does anybody have a diagram showing the directional flow of the cooling system ? .
my reason for this is , i have changed my rad and fan ( thanks for the kenlow jules ) cleaned out the matrix removed the engine drain , refilled the cooling system with oat , still not getting red hot air out the heater .
i have also done a mod on the cooling rail , car is not overheating and running fine,but the bottom cooling rail is not getting as hot as it should i think ...
so i now think that the problem lies with the thermostat not allowing the coolant to circulate ?

sometimes the heater blows warmish air on low fan , but i think when its on fast because the flow is not good enough the blower is cooling it down , without the fan on both flow and return on the matrix are red hot .
your thoughts please thanks mark

you most certainly have air in the system , when you refilled the system did you have the heater set high?. ito get of air and gunk from my system i un did top and bottom hose and ran a hose pipe through top hose allowing water to go right through system ,you wouldnt believe the muck that came out .. then filled it up and bleed it .you will need someone to top up while you bleed it as it takes a while for the air to escape .the lower the level gets the more air you will get in system .. mow i got a nice hot heater and no more over heating issues or hoses splitting cos of the prusse build up due to the air in system and coolant not being able to circulate around the system ...remember bleeding the system is not about letting the over fill of of coolant out to obtain the right level of coolant .to get rid of all the air it can take you up to an hour .when the air was all out my car the coolant flowed out the bleed value in one movement not slowing and speeding up and slowing again ..
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Last edited by chrissyboy; 4th April 2010 at 10:55..
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Old 4th April 2010, 11:12   #15
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the cooling system has been bled that many times i have shares in oat .

the matrix has been out and descaled , brand new rad , new moded cooling rail . the heater motor is working fine on all speeds , coolant level stays the same when checked at cold , deff sure the correct ammount 7.2 ltrs has gone in measured , system comes up to temp ok and stops at just a fraction under 9 oclock and stays there even in traffic fan kicks in , air con was serviced at the same time as new rad and kenlow fan and works fine ............. , i have extended the expansion pipework to above the hight of the bonnett the other day when refilling the system as a gravity system fills better the more head hight there is ...... the only thing it can be is an air lock but i just cant believe it the temp on the flow and return of the matrix is red hot not done a temp test as its ****** hot . will run her for a few weeks and if it is an air lock hopefully it will make its way to the highest point expansion tank ........... the air that is been blown out is ok , but not banging red hot. if still the same in a few weeks will have to invest in a pella and try that ........... ah well at least the weather is getting warmer and my air con is a1
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Old 4th April 2010, 19:44   #16
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Quote:
Originally Posted by markb63 View Post
the cooling system has been bled that many times i have shares in oat .

the matrix has been out and descaled , brand new rad , new moded cooling rail . the heater motor is working fine on all speeds , coolant level stays the same when checked at cold , deff sure the correct ammount 7.2 ltrs has gone in measured , system comes up to temp ok and stops at just a fraction under 9 oclock and stays there even in traffic fan kicks in , air con was serviced at the same time as new rad and kenlow fan and works fine ............. , i have extended the expansion pipework to above the hight of the bonnett the other day when refilling the system as a gravity system fills better the more head hight there is ...... the only thing it can be is an air lock but i just cant believe it the temp on the flow and return of the matrix is red hot not done a temp test as its ****** hot . will run her for a few weeks and if it is an air lock hopefully it will make its way to the highest point expansion tank ........... the air that is been blown out is ok , but not banging red hot. if still the same in a few weeks will have to invest in a pella and try that ........... ah well at least the weather is getting warmer and my air con is a1
have you tried taking the cap off the header tank, then squeezing the bottom hose near the rad, then work your way up squeezing all the water pipes you can get to?
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Old 4th April 2010, 19:55   #17
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tried everything, one thing i have noticed is when i remove the expansion cap to check the coolant level in the morning i get a hiss of pressure relief on a stone cold engine, so the system must be ok . unless this is not normal and the air lock is slowly moving up to the tank and i am letting it out when i remove the cap
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Old 4th April 2010, 22:16   #18
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Quote:
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when I remove the expansion cap to check the coolant level in the morning I get a hiss of pressure relief on a stone cold engine, so the system must be ok.
That doesn't sound so good to me to be honest. A stone cold engine cannot have residual pressure in the cooling system unless it's permanent gas that's been put in under pressure. That means a gas like CO2, in other words, exhaust gas. It would explain all your overheating/bad circulation issues.

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Old 4th April 2010, 22:56   #19
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mmmmm no mayo around at all , and she runs like a dream . i understand what you are saying , but if there were gasket or failure of something else surely there would be signs of some sort ? have run the engine with the cap off untill the level rises and put back on , there were no sign of air coming up . where could i get one of those water co2 testers from local motor factor shop
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Old 4th April 2010, 23:58   #20
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Most garages should be able to do the 'sniffer test' to detect exhaust gases in the coolant. I dare say you can buy such kits on eBay.
I'm thinking a cracked liner perhaps? A one way pump action?

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Last edited by T-Cut; 5th April 2010 at 00:07..
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