Corsa D Water Loss. Pressure Testing Cap And System 

First determine you actually have an airlock. check if you’re getting hot air from the heater with the engine fully up to temperature and the stat open, ( the radiator top hose will be very hot when the stat opens. If you’re getting hot air then you don’t have an air lock, it’s all circulating fine The bubbles are almost certainly from the small return pipe into the expansion bottle, the water drops in and can create bubbles that aren’t coming up from the engine. If that’s the case it’s normal and you just need to check the level daily for a few days. It’s often confused with bubbles from the engine. If the heater is NOT hot then you may have an air lock ( or the usual blocked heater, but you would have known that before you did the pump anyway). If one of the heater pipes is cooler than the other where they go into the bulkhead ( and the blower is off) then you dont have circulation, due to an air lock or blocked heater. Assuming the heater is good then it’s an airlock and it’s easy to get out. Turn off the car, let it cool a bit or you’ll get burnt, loosen the clip on the PUMP END of the long hose that goes to the heater, Remove the coolant cap and fill the bottle . Pull the hose up till it’s nearly off the pump and blow hard into the bottle ( you’ll have to wipe it clean first cos antifreeze tastes bad ) While it’s under pressure from your mouth just lift the hose off the pump a tiny bit and as soon as water comes out of the hose end ( it’ll come out of the pump immediately anyway, but you’re trying to push water through the heater and back to the pump) then push the hose back on. While it’s under pressure,. The airlock will be in the heater, that’s the only place it can be, so if you force water into the heater it’ll push the air along the hose and out. The hose must have water coming from it when you push it back on, if you let off the pressure it’ll just fall back into the heater and drag air with it. Takes 2 minutes to do. As soon as the heater starts working then the air is all out, Thermostats used to have a tiny hole in the disc to allow air to escape when filling up, they don’t have them anymore, but worth drilling one . About 2 mm.

Or alternatively you could pull off that heater hose and raise it up and feed water into it slowly to fill the heater while you keep your thumb on the pump stub to hold the water in. When the hose is full then push it on and try not to get any air back in it.

@@thpxs0554 heater has hot air and the hose is piping hot, the temperature in the secret menu is saying it’s not over heating but it’s still looking like it’s boiling, it’s definitely a head scratcher.

I’ve only just seen your reply, did you sort it out? They can suffer head gasket failure, if you pump it up like in the video and remove the plugs you may see water on the pistons, or a clean washed piston or a clean spark plug, they can have a blown head gasket and still run fine for ages, just a mis fire on cold start

Mozel savjet za mene glava ispitana piksne nove ravnjanja glava na opel merivi 1.7 74 kw ali kad smo upalili vodu vraca iz boce cim crijevo skinemo jedno onda ima voda al na prekide baca drugo crijevo nema vode samo zrak

It could be a faulty cap or it could be a genuine over pressure and the cap is working and doing its job correctly. The prime suspect if it’s over pressuring will be the thermostat, they can fail on all cars and cause overheating . You can just replace it or you can test yours in a pan of near boiling water to see if it opens right up. If it’s failed then you can cut the guts out of it and put it back in ( I think the sealing ring needs the rim of the stat in order to fit properly, hence I cut the guts out of them and put the frame back in , this will get you out of trouble until you get a new one, but if it’s still overheating then it could be a failed water pump, if the heater still gets hot then the water pump is ok. If it doesn’t get hot and you don’t have an air lock then the pump is suspect but it’s a pain to get off and it’s easier to test for a failed head gasket before you start pulling it apart. Basic head gasket checks are …. Does it have bubbles coming up into the bottle if you remove the cap and look in when it’s cold preferably. Is it misfiring, especially from a cold start. Then it runs ok after a few seconds .I’d remove the spark plugs and check the compressions, if you don’t have a compression tester you can at least look at the plugs and see if one of them is noticeably cleaner, due to being washed by coolant from a faulty head gasket. Also look down the plug holes and shine a torch if you need to so you can see if you have a much cleaner piston in one cylinder. If you look down the plug holes in the morning before you first start it you may see coolant on the piston that’s leaked in overnight. Sorry I can’t give you a simple answer, several things can cause your symptoms and guessing just wastes time and money. If you buy a bottle of head gasket detector fluid and put some in the bottle and run it you’ll know immediately if the gasket has failed cos I’ll change colour from the combustion gasses, which may be the easiest and quickest way to eliminate or confirm the head gasket before you do anything else at all. Especially if you’re not confident dong several checks removing things

@@thpxs0554 Thanks for that. Yeah what makes me think it isn't gasket failure is it just runs too well. No lumpiness or pinking at all, and no loss of horse power. The heating is fine so it's not the pump. But I've had problems with expansion tank caps before. It just gets stuck and the plug and yellow cap separate I have to pour boiling water on it to get it out. That cap is fairly new after it happened before. But whatever it is it just keeps pissing all the water out of the little overflow pipe. So I guess the next thing would be to check the thermostat. That I can do I've, done it before.