That is the right way around Sven.
My new challenge - 1964 ID19F Safari
- Thread starter bleudanube
- Start date
Thought it was… maybe I am seeing white mice - maybe I just put the thermostat back in, shove the 4 psi cap on and watch the overflow….
Hi
Have you got an air lock somewhere? The air expanding as it warms, pushing the coolant out of the system?
Your other question about flow: with the thermostat closed, the pump is just circulating water around the head and block. While the pump could still force water into the bottom radiator pipe - and so the radiator core - there is no outlet for it at the top of the radiator and so no flow. I expect it would warm a little, but not as much as as the coolant circulating in the head/ block.
My car has one of the flaps in the aluminium radiator chute (steel actually) that cuts off air to the radiator to help the car reach normal running temperature quicker. Now i think about it, when the engine is cold the thermostat is closed and there is no coolant flow through the radiator. So stopping air flowing over the radiator fins wouldn't seem to be much of a help? perhaps the main purpose of the flap is that it stops cooler air entering the engine bay at all, and so aids that way? I need to think this whole 'cooling' thing through....
Have you got an air lock somewhere? The air expanding as it warms, pushing the coolant out of the system?
Your other question about flow: with the thermostat closed, the pump is just circulating water around the head and block. While the pump could still force water into the bottom radiator pipe - and so the radiator core - there is no outlet for it at the top of the radiator and so no flow. I expect it would warm a little, but not as much as as the coolant circulating in the head/ block.
My car has one of the flaps in the aluminium radiator chute (steel actually) that cuts off air to the radiator to help the car reach normal running temperature quicker. Now i think about it, when the engine is cold the thermostat is closed and there is no coolant flow through the radiator. So stopping air flowing over the radiator fins wouldn't seem to be much of a help? perhaps the main purpose of the flap is that it stops cooler air entering the engine bay at all, and so aids that way? I need to think this whole 'cooling' thing through....
Air trapped in the system was my thought as well. Not knowing the cooling system on this car is difficult to give a proper suggestion but if the coolant is overflowing before the thermostat opens there isn't any other suggestion apart from a head gasket failure.
Are there any bleed points you can access to reduce the amount of air in the cooling system?
Cheers, Ken
Cheers, Ken
That thermostat does not appear to have a relief hole or a jiggle pin to allow some minimal flow between the two sides for pressure equalisation during the period before the thermostat opens properly.
As Peter says, some thermostats have small bypass holes built in to help air come to the highest point and to reduce the possibility the cooling system going unstable when the thermostat starts to open and lets in too much cool coolant.
Cheers, Ken
Cheers, Ken
Easy enough to drill a couple of holes into it… how big a hole? Is two holes of 2mm enough?
I think 2mm would probably do the trick. The mounting of the thermostat in the rubber ( neoprene ?? ) hose would not allow good heat conduct so it may take an unusual amount of time to heat and open compared with a metal housing mounted thermostat.
I thought it was normal practice to drill a bypass hole in a DS thermostat before you fitted it 
I thought they didn't have one as per picture. Seemed odd, but DS Citroens are alien to me. I would go with one 3mm hole. Did the original part have one?
If the outside temperature is very cold then the engine can’t reach normal operating temperature because the cooling system is working to well. The flap is there to restrict the air flow and keep the engine warm. 2CVs have a grill muff for the same reason.
The only real way to bleed a DS cooling system is to loosen a hose clamp. There aren’t any bleed valves on the radiator or head.
It’s a sealed system so coolant can’t just disappear, it has to have gone somewhere.
Hi.
I have no experience with the cooling system on this engine. But I have some thoughts on the thermostat.
I note the thermostat is 160F = 71C. I would expect it to commence opening at 71C, you have mentioned it is fully open at 80C, so in my opinion it is functioning correctly. As with most valves, the rule of thumb is you get 80% flow from 20% opening.
It seems to me that for the thermostat to commence opening the hot water needs to be able to transfer heat into the wax pellet in the base of the thermostat. I don't know if the thermostat is positioned in a "dead" zone of the engine that gets little water circulation when the thermostat is closed. Depending on how much water can bypass the valve in the thermostat when it is closed, if no or little bypass this might also trap air upstream of the thermostat until it opens. Contributing to your bleeding problems and coolant loss.
I agree with what others have mentioned, that a small bypass hole would enable some water flow to bypass the thermostat valve, allowing air bubbles to bleed through, but more importantly allow the cool water to purge and the hot water to act on the wax pellet. I can recall seeing a small 2mm Dia. notch in the valve edge of thermostats, I assume for the reasons stated above. If there is no bypass I would proceed to drill a 2mm Dia hole in the other flange, ideally positioned at the top of the hose when installed.
Hope this assists.
Cheers.
If the engine has no means to bleed air out, I would refill the whole system through the radiator with the radiator top hose disconnected at the thermostat. When water runs out the open point, you can put the thermostat hose back, but there will be air above it. Not necessarily a problem, but you probably have to run the engine with the radiator cap removed until the thermostat opens and coolant comes through the hose. This will warm up the hose to the touch. At this point, you have to keep topping up the radiator as air trapped in the system will bleed out.
If you have a hole in the thermostat to allow coolant to level out, you don't need to disconnect the hose. You still need to fill up the system but it will go slowly once the coolant arrives at the thermostat. When all is filled up, you still need to run the engine with the radiator cap off until the thermostat opens to allow whatever air is still trapped in to bubble out. Keep topping up the coolant otherwise air can be drawn back in the system again. When no more air bubbles out, you can top it one last time until it reaches the overflow to the expansion tank and close the radiator cap.
All the above is done with the passenger heater tap open (position hot) so coolant can push any air in the heater core out towards the radiator.
All of that is however only theory if the heater core or any of the engine is higher than the radiator cap. In this case, you really need a bleeding valve otherwise you're going to struggle to get all the air out.
I can not really believe there is no provision for bleeding the system, maybe some tap on the heater core entry or somewhere on the engine block or whatever.
Not saying it is impossible.
All the cars I have had have some point where you can open the system to allow air to bleed out at the highest point. Some cars have more than one such point and each has its own bleeder.
I would check the car again and if indeed there is no such bleeding point, I would install a couple. Easiest is at the heater core entry, just a tap in the hose coming out of the heater at the bulkhead. Renault 12 (and similar) have such a tap you can get easily and install in the hose. It is just a plastic (or aluminium or brass depending on how old it is) inverted T piece with a thumbscrew in the vertical of the T.
The other place is the water pump itself. A close examination might reveal a boss cast into the body where the bleeder is suppose to be. This is because if you have air trapped in the pump your cooling system will never work.
If the pump is not the highest point, there should be a bleeder in the cylinder head perhaps above the exhaust side, opposite end to the water pump. That is again a sensitive area. If any air is trapped there you will do a head gasket in no time flat and possibly burn some valves in the process too. That is the hottest part of the engine and usually the first place cold coolant is pumped from the radiator.
Best of luck.
If you have a hole in the thermostat to allow coolant to level out, you don't need to disconnect the hose. You still need to fill up the system but it will go slowly once the coolant arrives at the thermostat. When all is filled up, you still need to run the engine with the radiator cap off until the thermostat opens to allow whatever air is still trapped in to bubble out. Keep topping up the coolant otherwise air can be drawn back in the system again. When no more air bubbles out, you can top it one last time until it reaches the overflow to the expansion tank and close the radiator cap.
All the above is done with the passenger heater tap open (position hot) so coolant can push any air in the heater core out towards the radiator.
All of that is however only theory if the heater core or any of the engine is higher than the radiator cap. In this case, you really need a bleeding valve otherwise you're going to struggle to get all the air out.
I can not really believe there is no provision for bleeding the system, maybe some tap on the heater core entry or somewhere on the engine block or whatever.
Not saying it is impossible.
All the cars I have had have some point where you can open the system to allow air to bleed out at the highest point. Some cars have more than one such point and each has its own bleeder.
I would check the car again and if indeed there is no such bleeding point, I would install a couple. Easiest is at the heater core entry, just a tap in the hose coming out of the heater at the bulkhead. Renault 12 (and similar) have such a tap you can get easily and install in the hose. It is just a plastic (or aluminium or brass depending on how old it is) inverted T piece with a thumbscrew in the vertical of the T.
The other place is the water pump itself. A close examination might reveal a boss cast into the body where the bleeder is suppose to be. This is because if you have air trapped in the pump your cooling system will never work.
If the pump is not the highest point, there should be a bleeder in the cylinder head perhaps above the exhaust side, opposite end to the water pump. That is again a sensitive area. If any air is trapped there you will do a head gasket in no time flat and possibly burn some valves in the process too. That is the hottest part of the engine and usually the first place cold coolant is pumped from the radiator.
Best of luck.
Definitely no bleed screws on a DS. The radiator is the highest point. They aren’t known for air locks provided you fill the system with the heater tap open. You can aid the bleeding by parking the car with the nose pointing slightly uphill if you really want.
Is the system pressurised or is it atmospheric? Does it have a pressure relief valve on the expansion tank?
And where is the water pump height wise? Bottom of the system pumping up or top of the system pumping down? or somewhere inbetween?
And where is the water pump height wise? Bottom of the system pumping up or top of the system pumping down? or somewhere inbetween?
This is an old system with no bleed points or expansion tank. The radiator cap is the highest point for filling. It is a very low pressure system too ... 4 or 7 PSI. The thermostat it located IN the top radiator hose, not in a metal housing. Perhaps running it without the thermostat in place would allow bubbles to be seen and verify the source/amount of the water being displaced.
My understanding of thermostat controlled cooling systems with the thermostat fitted in the top hose is that there must be a bleed hole in it to allow some circulation so that it will detect temperature rise from cold. No circulation, no signal to open . Simples !
Thanks for all the thoughts and comments. I have been running it for a few hours driving without the thermostat, but, as it’s cold in Melbourne, the head temp (using the Engineguard bolt on sensor) didn’t get higher than 55 degees where normally it would run at 67-70 degrees.
I will drill a small hole, shove it back in, run it with the cap on and see whether anything pushes out of the overflow. If not - all good, if it does keep leaking I keep investigating.
I will drill a small hole, shove it back in, run it with the cap on and see whether anything pushes out of the overflow. If not - all good, if it does keep leaking I keep investigating.
When I bought a thermostat from Cit Classics the drop box on the item stated a 2mm hole should be drilled in the item before fitting