Cooling system/ focus 02

disconnect both heater hoses at the motor, blow into either one to unclog it

1. The radiator cap if working correctly it will release pressure in the system provided the cap you have is the correct pressure setting. If you are having a problem with pressure then replace the cap with a new radiator cap with the correct pressure setting. Do not use a cap with a pressure setting other than the original equipment pressure spec. So you do not go to the parts store and buy any radiator cap on the shelf that fits because they come with different pressure ratings and some of these will be totally unsuitable for your car.

2. If the pressure valve is stuck in the "old" cap the pressure release system will not work.

3. Overheating
Air pockets in the cooling system can definitely cause overheating and can retard coolant flow through the system. If you are draining the radiator to replace the coolant or replacing the radiator you need to follow the correct procedures for bleeding air out of the system for that particular engine after coolant refilling. Some engines have bleeder screws on the cooling system to assist in the air bleeding procedure and some don't.

There are various causes for overheating so don't assume it will necessarily be solved by bleeding any remaining air from the cooling system and replacing the radiator cap with one that works.

Other causes can be...........
1. Faulty cooling system thermostat. (Replace the Thermostat)
2. Faulty water pump, especially if the impellers have corroded away or have disintegrated in the case of those design genius water pumps with plastic impellers. (Replace the water pump)

3. Cooling fans not working and if so the cause needs to be tracked. Check that your fans are kicking in. If the engine is overheating the fans should be running because they will switch on when the coolant reaches a specific temp and well before the coolant gets excessively hot.

4. A partial blockage in the coolant passages inside the engine but not in the radiator if you have a new one. If the coolant is not changed at the required intervals(frequently the case with many owners) or is over diluted with water you can get a build up of debris. If products like stop leak have been used in the system this can create similar problems with partial blockages inside the engine coolant passages.

5. A compression leak into the cooling system.
If you have bled air from the system and have continuous air bubbles in the cooling system I would suspect a compression leak. In that event a basic leak down test will show if you have compression gasses leaking into the cooling system and from which cylinder(s). The spark plug is removed and compressed air is forced into the cylinder via the spark plug fitting and air bubbles will show up in the coolant of there is a leak into the cooling system.
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Have the problem with overheating addressed immediately. Running the engine with an overheat condition will cause expensive engine damage many times the cost of fixing the overheating issue.

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With the engine cold, turn the heating controls to hot, remove the coolant cap, start the engine and leave running on idle till the car gets to working temperature (so the thermostat opens) watch the coolant bottle to see if air bubbles escape (purges) then leave running till no air bubbles are seen (about another 15mins) then put the coolant cap on BEFORE turning engine off!

sounds like air in system ...
Leave the radiator cap off, turn the engine on and let it run until the radiator "burps": You will see the coolant level drop and may see or hear a large air bubble come to the top as the system burps.
Keep an eye on the temperature gauge throughout this process

Refill the radiator to the top and coolant reservoir as needed. Put the radiator cap back on. Note that if the engine runs hot after this procedure there may have been another pocket of air that "burped." Let the engine cool down and then add more coolant to both the radiator and the coolant reservoir.

Rasie front of car on hill and jack stands. This will help purge air trapped in system. Leave radiator cap loose, cold engine. Run engine until upper hose is hot and burps air. Shut down, as it cools keep the radiator and reservoir full. Tighten cap and it should **** from reservoir as it cools.

you still have air trapped in the cooling system. Get front of car as high up as you can on a hill. Cold engine - loosen radiator cap, fill with 50/50 antifreeze mix. Start engine and run until upper radiator hose is hot (thermostat open). Engine should burp air and maybe spill some coolant, that's ok. Once burped, tighten cap, shut off engine and let it cool down while keeping the reservoir full. It will **** coolant out of reservoir as it cools. Keep it full.

If still cold air, take to a shop that has evac/fill equipment; they will **** air out and repalce with coolant. About $80.

gerry

usually this is air trapped in the system. Try leaving the cap loose on cold start and run engine until upper hose gets hot (ie thermostat opens). That should burp air. Then keep system full as it cools down. so it uscks coolant back in as it cools. Then, tighten cap.

Hi... Be sure to put your heater controls to hot when you bleed the engine coolant, run the engine up to normal running temp and top up as neccessary... you may have an air lock in the heater matrix. Please let me know how you get on....

you could have an air pocket in the cooling system that has to be burped. With a cold engine, park uphill and leave the radiator cap loose. Fill radiator and coolant reservoir. Start engine with cap loose and run at 1500 rpm until temp gauge reads normal. Feel if top radiator return hose from engine to radiator is hot. If yes, coolant is flowing and thermostat is open. If cold, thermostat is not staying closed until engine is hot.

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