Expansion tank

[pitslayer]

Out of curiosity, the expansion tanks on the VR4, are they actually ment to hold water, I know it sounds silly but I have given up on in filling mine up, no matter how much I put in, it always ends up bone dry, car doesnt overheat and the rad is always full to the top, but the expansion tank is always dry, fill it up, go for a run will be empty again

Where does the water go, it doesnt leak out anywhere, I can fill it right to the top aswel, and it uses all the water in it

[scott.mohekey]

Sounds like you could have a blown gasket somewhere. Head, water pump, etc.

[Kieran]

If you keep filling it up and water is getting out then you most probably have a leak somewhere. Never heard of them emptying the tank repeatedly. Often they'll overflow when the car is hot, but not actually run totally dry - And that usually happens on track only.

I'm wondering here.... is the expansion tank cracked? I wonder if it's just that the tank is leaking.

If there's no obvious damage and no external leaks elsewhere then the car's using water somewhere. Might be worth getting a BHG tester kit.

[pitslayer]

there aint any mayo anywhere, just the tank just stays empty always has I could fill it up tomorrow and it will be empty by end of the day, but car never overheats,

[scott.mohekey]

Where have you looked for mayo? Also, a leak from the water pump or thermostat housing won't show up as mayo.

[pitslayer]

in the oil, under oil cap, I know the water pump has been done, and there is no leak from that area, car never steams or has water underneath , radiator is always full, all be it with rusty water

[scott.mohekey]

Here's some of the places it could be leaking:

Pipes to heater in cabin (my ST25 had this problem, had to get new seals), was visible as water pooling on the back of the gear box.

The heater in the cabin. Could be leaking water into the cabin somewhere.

Drain plugs on the block on either side of the heads.

Coolant pipes to turbos.

Coolant pipes to throttle body.

Also, a blown head gasket might not show up as mayo in the oil, if its leaking water directly into a cylinder, it will be getting burned and being sent out the exhaust.

[pitslayer]

its not loosing any coolant out of the radiator system, as that always stays the same level in the radiator

Will have to dig out my compression tester, no idea where it is, not had to use it in a long long time

[scott.mohekey]

Someone else can correct me if I'm wrong on this, but doesn't the radiator system suck water from the expansion tank in some cases?

[Kieran]

Someone else can correct me if I'm wrong on this, but doesn't the radiator system suck water from the expansion tank in some cases?

That's quite correct. As the cooling system's temperature drops, it will drag water back in from the expansion tank.

Pits - That's probably why the level in the radiator doesn't change.

[Kieran]

......radiator is always full, all be it with rusty water

........You posted some while ago (with picture) that you'd changed the coolant?..............

[scott.mohekey]

Sounds to me like you have a leak in the coolant system somewhere.

[pitslayer]

I wouldnt have a clue, its not a pressurised system expansion tank side, I never loose any water from the system itself, the expansion tank empties,
No visible leaks
No mayo
No water in or under the car
radiator full
no over heating

[AlanDITD]

If it was HG it would draw water form the expansion tank then it would burn it off i the system. Check your rad cap

[bradc]

Perhaps try NOT filling the expansion tank for a while and see if the radiator level drops at all

[Wodjno]

Perhaps try NOT filling the expansion tank for a while and see if the radiator level drops at all

This is exactly what i was going to suggest .. If you top the expansion tank up repeatedly then your rad will never ber down on water, as thm is sucking the water back out of the expansion tank to replace what its losing.. So it would never overheat and there won't be any leaks..
Don't fill up the expansion tank and monitor the temp and the water in the rad frequently..

[Subaru ETA]

id suggest checking your rad cap

[White Lightning]

Often they'll overflow when the car is hot .... And that usually happens on track only.

Unless you have just topped it back up to the full mark ... and then had fun chasing a 911 Turbo down the local dual carriageway ... whilst bedding your new brakes in