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Really Dumb Coolant Question

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Hi, I'm just doing my winter checks and noticed that the pink coolant level (I assume that's what it is, in the tall white translucent plastic tank) is a centimetre or two below LOW so I figure that should be adding more coolant. Check the handbook. Remove coolant cap (the silver one with the yellow warning, just right of the centre bonnet release catch). Oh, that's full. Funny. Look at white plastic tank again. Oh, it has a black plastic cap on it, and a rubber tube going down into it running from below the silver/yellow cap in the centre. So if the white plastic container's empty, why is fluid right to the top of under the silver cap and not draining into the white container?

So to cut to the chase, how do I top up my RAV4 with moore coolant? Where do I stick it and what is the difference between the two caps? Is anyone else confused by this? I've never seen a car befre with (a) apparently two places you could add coolant and ( B) if it's the white plastic container, how do I pour it in given that the rubber tube is taking up most of the space around the cap. Maybe I'm think but I didn't think the book was very clear and I searched the forum and didn't see any similar questions.

Car in question is 2 litre VX automatic, 2001 model (second generation) petrol.

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It can do that because there is a valve in the radiator cap. It uses the coolant in the tank to suck in as the system cools down. A similar but opposing valve allows excess coolant to flow back to the tank as the system heats up. It is constantly transfering coolant from the tank to the radiator and back. When the engine is cold the radiator will always be full as long as there was something in the header tank.

To start from scratch, top up the radiator ONLY when the engine is cold - you can seriously scald yourself messing with that when the engine is hot. Then just top up the coolant in the header tank to the max line. Check it again for a couple of days only adding coolant to the plastic header tank NOT THE RADIATOR. Usually leaks are very slow so if it needs top up every day after the first couple you might have a leak that needs attending to. Only use pink coolant.

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Maybe I wasn't quite clear enough, you are describing my problem in that under the radiator (I assume) cap, the silver one with yelow warning notice on, coolant is right up to the top, but the plastic tank is empty. However I'm not clear down which of the two caps I have to pour extra coolant to top up. Are you saying that to top up, I have to take the black cap (through which runs a black tube) off the translucent plastic tank, and pour around the black tube into that tank, rather than into the black tank under the silver/yellow cap? Sorry to be dumb but I couldn't see any indication in the handbook and the logical cap to be putting coolant in is the silvery one in the middle since it says Coolant, but the coolant level there is full.

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You won't find it in the book because you shouldn't really ever get to this stage. If you do it from cold (and I urge you to do it from cold) you can firstly top up the radiator under the metal cap with the yellow sticker. Fix that cap back fully clockwise and do not touch it again. You now fill up plastic bottle with the black plastic cap with coolant to the max line. Then run it until the engine is warm and you may see that level go up or down but away from the max line. Only when it is cold again can you check and adjust it back to the max line. Don't worry if it is a bit over but add if it is under. Do not touch the metal one again at any time or you will have to start again - that will automatically sort itself out. You only ever add to the plastic bottle keeping it somewhere near that max line. Keep an eye on it for a few days to make sure it stays level. You can please yourself but I'm going to bed!!!

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