Refilling the cooling system
Discussion
What is the best way to de-air the cooling system on a 280i SII?
I replaced the fan switch which is mounted low on the nose radiator and in the process (which took 2 weeks from removing the old one and finding the new one) dumped a lot of coolant into a drain/catch pan. With the new switch installed, I went to refill the system (from the expansion tank and the swan neck) and only got 1.5 gallons in. I knew that was too little but started the car hoping as the thermostat opened I could add more. That didn't work as the radiator was cold and the temp gauge went over 90C. I'm letting it sit overnight as the thermostats is drilled and the coolant level should equalize over time. I think the problem is with the thermostat closed, I'm getting an air lock between the swan neck and the radiator.
I've changed the thermostat before but can't remember if I had an air lock or how I resolved it.
I can muddle around with cracking hoses but am I missing something easy? Thanks Grady
I replaced the fan switch which is mounted low on the nose radiator and in the process (which took 2 weeks from removing the old one and finding the new one) dumped a lot of coolant into a drain/catch pan. With the new switch installed, I went to refill the system (from the expansion tank and the swan neck) and only got 1.5 gallons in. I knew that was too little but started the car hoping as the thermostat opened I could add more. That didn't work as the radiator was cold and the temp gauge went over 90C. I'm letting it sit overnight as the thermostats is drilled and the coolant level should equalize over time. I think the problem is with the thermostat closed, I'm getting an air lock between the swan neck and the radiator.
I've changed the thermostat before but can't remember if I had an air lock or how I resolved it.
I can muddle around with cracking hoses but am I missing something easy? Thanks Grady
Hi Mate...Ideally as said get the front up a tad on a jack on level ground then slowly fill the radiator up first...Then fill the expansion tank ..Massage all the large hoses..Especially the lower rad to thermostat one..Put the heater on the hot position and turn on to full...Start the car with the expansion cap off and warm by holding the throttle open to around 2000rpm on the throttle body...Test with your finger to feel the temperature of the water in the tank...Once it starts to warm then put the cap on and warm until normal operating temperature is reached.
Switch off and squeeze the large hoses to make sure they are not under pressure as the thermostat should of opened by now....Allow to cool slightly and then carefully whilst covering with a towel remove the expansion tank cap to check the level...Top up if needed...
If you can drive the car and keep an eye on the temp gauge..Allow to cool for a few hours and check the level once more.
The only place an air lock can occur really is in the top water inlet.
Hope this helps.
Ziga
Whoops ...Nearly forgot...Only use the classic blue coolant as the water pump is a bi-metal construction.
Switch off and squeeze the large hoses to make sure they are not under pressure as the thermostat should of opened by now....Allow to cool slightly and then carefully whilst covering with a towel remove the expansion tank cap to check the level...Top up if needed...
If you can drive the car and keep an eye on the temp gauge..Allow to cool for a few hours and check the level once more.
The only place an air lock can occur really is in the top water inlet.
Hope this helps.
Ziga
Whoops ...Nearly forgot...Only use the classic blue coolant as the water pump is a bi-metal construction.
At the front of the plenum, right by the AUX air device there is a T junction of coolant hoses. One of the hoses goes back to the expansion tank. Remove the T from the lower hose and with a small funnel fill through this hose. It takes awhile because the hose is not that big, but being the highest point in the system it's the best way to get all the air out. Once filled open the pressure release valve on the cap on the swan neck tube until coolant comes out. Then pore some more coolant into the funnel until its full again.
I suggest adding some RedLine Water Wetter into the mix. It works.
I suggest adding some RedLine Water Wetter into the mix. It works.
Edited by GBinUSA on Thursday 21st April 16:25
I agree with all the above, Ive always found that burping the top hose and slowly topping up at the swan neck works well. The thing that concerns me is that Zig says only use the blue coolant. Ive just replaced mine with the orange/pink stuff, it sounds like this is no good. Please advise.
By the way, car passed its MOT today. First time in Ten years that I have driven her. What a car! Its all come flooding back to me, VERY addictive!
By the way, car passed its MOT today. First time in Ten years that I have driven her. What a car! Its all come flooding back to me, VERY addictive!
wedgewood said:
I agree with all the above, Ive always found that burping the top hose and slowly topping up at the swan neck works well. The thing that concerns me is that Zig says only use the blue coolant. Ive just replaced mine with the orange/pink stuff, it sounds like this is no good. Please advise.
By the way, car passed its MOT today. First time in Ten years that I have driven her. What a car! Its all come flooding back to me, VERY addictive!
Well done on the pass....I know that you must never mix the orange and green as it turns to gel..As long as you have flushed thoroughly before replacing coolant you should be okay...Just bear in mind that they are different coloured because of the additives...The blue is recommended for anything pre-1990...I said this in this post because my 1982 280i had a mixed metal ...(Sorry not bi metal) water pump parts and the additives in the later coolant can corrode it very quickly.By the way, car passed its MOT today. First time in Ten years that I have driven her. What a car! Its all come flooding back to me, VERY addictive!
Not sure on the V8 but i used blue in mine as she is 1987.
Have you got the radiator in the nosecone ?
On the earlier ones like mine, you can fill the radiator directly (it has a cap) to get most of the way, then close rad cap and then squeeze the top hose to force air bubbles into overflow tank, and top up overflow. After warming up a few times bubbles are expelled naturally.
On the earlier ones like mine, you can fill the radiator directly (it has a cap) to get most of the way, then close rad cap and then squeeze the top hose to force air bubbles into overflow tank, and top up overflow. After warming up a few times bubbles are expelled naturally.
Yes, the radiation is in the nose and I think almost all the coolant had drained out of the system. I've never had a problem refilling the system and then bleeding the last little bit off via the T fitting as suggested (thanks for reminding me). For some reason, this time it didn't appear that the coolant was displacing the air as only took a gallon and the engine was hot and the radiator completely cold.
I suppose it could be a bad pump/thermostat but that seems unlikely. The thermostat is drilled to relieve any trapped air so I'm hoping to find that by sitting a day, the coolant has displaced the air and I just need to add more. We will see.
Also, I don't know about 'blue' coolant - no wonder you use blue silicon hoses. Over here the traditional kind is green and the new stuff is orange. I've gone with the green. Grady
I suppose it could be a bad pump/thermostat but that seems unlikely. The thermostat is drilled to relieve any trapped air so I'm hoping to find that by sitting a day, the coolant has displaced the air and I just need to add more. We will see.
Also, I don't know about 'blue' coolant - no wonder you use blue silicon hoses. Over here the traditional kind is green and the new stuff is orange. I've gone with the green. Grady
Grady said:
I don't know about 'blue' coolant - no wonder you use blue silicon hoses. Over here the traditional kind is green and the new stuff is orange. I've gone with the green. Grady
Blue and green are almost identical just different temperature extremes...You can mix them together...
Red/Orange/Pink are for later cars and these can be mixed together but the blue/Green cannot mix with the Red/Orange/Pink....
mrzigazaga said:
Blue and green are almost identical just different temperature extremes...You can mix them together...
Red/Orange/Pink are for later cars and these can be mixed together but the blue/Green cannot mix with the Red/Orange/Pink....
It's a beautiful spring day here and all that color mixing is making me think that mixing a rum and fruit cocktail sounds better the pressure washing the house! Red/Orange/Pink are for later cars and these can be mixed together but the blue/Green cannot mix with the Red/Orange/Pink....
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