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Anders Dinsen
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« Reply #93 on: July 21, 2012, 11:59:17 am » |
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I think the problem is not flow but that it can't keep pressure - i.e. I suspect you have a water or air leak somewhere in the system. Increased flow (until a certain point) means more cold water through the engine and the temperature drops and boiling stops, but this only works until the engine is really hot. When the system is pressurized, the temperature can go over 100 deg C and it won't boil. Finding the leak can be difficult since it may not be clearly visible on the engine - small amounts of water are very difficult to see. I had a leak around the timing chain cover on my 2.2 some years ago, and I was luckly spotting it when it sprayed the water out - the engine is idling in this photo. This very small leak gave me the exact same problem as you have now. But it could also be a cracked hose, a pipe, or as simple as the cap not fitting tightly on the header tank. It doens't even have to leak water - if air is leaking out the system somewhere, the pressure can't increase over 1 bar, and you're in trouble (boiling!) A bit to think about there... Have a great holiday, /Anders
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1982 Talbot Matra Murena 2.2 prep 142 2017 BMW i3 "Charged Professional" 94Ah
Used to own: 2001 Renault Matra Grand Espace "The Race" V6 24v 1997 Renault Matra Espace 2.0 8V 1987 Renault Matra Espace J11 2.2
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Oetker
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« Reply #97 on: July 21, 2012, 02:53:21 pm » |
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It doesn't do anything except connecting the 6 mm vent hose from the thermostat housing to the 16 mm connection on the top of the header tank. I've got a refabricated header tank with a 6 mm connection. The hose is there to vent out air out of the cooling system from the thermostat housing.
It has a function. It is to cut of flow a bit. Th water-flow was to strong without the narrower, generating air in the system at the expansion bottle. This air get trapped at the heater core generating irritating sounds. According to the manual updates it is part of a modification. I never tried, but I think using a thermostat with automatic degasser would be a good solution to get trapped air out. The hose with the tap can be replaced by one without. A experiment for later, because at the moment no need to work there.
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I feel like Jonah, only my fish looks different. Murena 2.2 Red 1982. Murena 1.6 black on places.
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Oetker
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« Reply #99 on: July 21, 2012, 07:55:26 pm » |
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Ok, I will also check the narrower. It should be mounted with the larger end pointing to the header.
By the way, what is the normal water temperature at idle in Murena 2.2? And during normal use?
I have a VW Golf III for daily use, it has quite constant water temperature about 90 degrees. In winter at -20 C it is 85 degrees, in summer above +35 C it is 90 degrees (maximum 92 at high load). It does not matter if the engine is at idle or on motorway. So it is strange for me, that the water boiling at idle in Murena...
My water temp at idle goes up to 95C then the vent kicks in and it drops back to around 85C. It takes more then 5 miles for the car to warm up to around 80C It is a bit difficult to get all air out the system at first. a while ago I refilled the system andreplaced a hose and had exactly the same boiling. Once the thermostat had opend it was OK. Trapped air can be a bit difficult with this cars. Maybe after your holyday the problem is vanished
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I feel like Jonah, only my fish looks different. Murena 2.2 Red 1982. Murena 1.6 black on places.
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Anders Dinsen
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« Reply #101 on: July 22, 2012, 07:54:11 am » |
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The water temperature can be higher inside the cylinder head than the reading in the termostat housing, so you can't conclude that there will be no boiling just because the temperature is below 100 deg C. If the system is not pressurised perfectly, there will be localised boiling in hot areas, e.g. on top of the combustion chambers. Localised boiling is very problematic because boiling water has little or nor cooling effect, but in a properly pressurised system, localised boiling doesn't happen. About the reducer in the vent hose: I didn't know that there had been a modification of this, but it sounds likely. Note that the reducer connects the 6 mm hose exiting from the side of the thermostat housing to the 16 mm hose on the header tank, so it's the other way around compared to what you mention below. A recommendation: When you get home and start looking for the problem, don't exclude any parts just because you're sure they're done right - e.g. changing gaskets always involves a risk that the new gasket fails after a short while. I'd start with where pressure is generated: The water pump, looking very carefully for any signs of leaking water. Then working my way forward to the engine, cylinder head, thermostat etc. By the way, how was the engine sealed? With the original paper gaskets? Positive thinking, yes that's just what you need! And some systematic fault finding and experimentation /Anders
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1982 Talbot Matra Murena 2.2 prep 142 2017 BMW i3 "Charged Professional" 94Ah
Used to own: 2001 Renault Matra Grand Espace "The Race" V6 24v 1997 Renault Matra Espace 2.0 8V 1987 Renault Matra Espace J11 2.2
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klumzer
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Posts: 370
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« Reply #103 on: August 05, 2012, 06:28:20 pm » |
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My water temp at idle goes up to 95C then the vent kicks in and it drops back to around 85C. It takes more then 5 miles for the car to warm up to around 80C It is a bit difficult to get all air out the system at first. a while ago I refilled the system andreplaced a hose and had exactly the same boiling. Once the thermostat had opend it was OK. Trapped air can be a bit difficult with this cars. Maybe after your holyday the problem is vanished So, the problem is almost vanished. We managed to get out some air from the system, now it is much better. But I have to change one of the hoses at the top of the thermostat housing. When the thermostat opens, it is leaking... Probably we have both problem, air in the system and bad pressurization. Another interesting thing with the Clio expansion bottle: We filled it a bit above the "Min" marking. After starting the engine first (cold engine) the level was decreasing and the water disappeared from the bottle. We filled a small amount of water to the bottle. When the engine became hot the bottle was full without any air... Water did not come out at the cap.
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« Last Edit: August 05, 2012, 06:38:52 pm by klumzer »
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