Coolant leak on e46 318i 2004

[pontiac_gto]

Hi Friends,

I have coolant leak on my e46 318i. I know there are loads of threads regarding coolant matter in this forum and other forums too. But I did not get what I want yet. Hope you guys will help me out. I did not replace expansion tank yet. I just need to confirm the actual cause of the issue. Whether it is Expansion tank or Radiator or any other thing. I have uploaded the picture of leak point (Red Arrow). Hope you guys point out the actual cause by looking at the pic. 
Thank you very much for your time. 

[pug306xsi]

which side is this from?

Possible leak from the water jackets?

[Rumesh88]

The picture is from the bottom side of the expansion tank. Any chance of coolant spilling out from the top and dripping down? 

[Twin Turbo]

YES , first confirm you actually have a leak as you do not fill the expansion tank to the brim.

bleed system and check for good measure

TT.

[pontiac_gto]

When I drive a car about 10 mins its starting to leak the coolant from that location (Marked as red). Even if I filled the tank full, it will on the coolant light after about 50km. Adn there are no sign of leak anywhere other that this point. So I guess this is a leak. And heard this is common issue for some bmw models. 

[Twin Turbo]

Stop driving the car,..Coolant loss will give rise to massive head aches for both you and the engine.  youshould never brim the expansion tank as there will not be any space for the coolant to expand into.

Get a suitably qualified and experienced mech to look at the rad under pressure.

Goodluck.

TT.

p.S, Also get the cooling fan operation checked as it's electric,./

Edited December 2, 2016 by Twin Turbo

[Rumesh88]

40 minutes ago, pontiac_gto said:

When I drive a car about 10 mins its starting to leak the coolant from that location (Marked as red). Even if I filled the tank full, it will on the coolant light after about 50km. Adn there are no sign of leak anywhere other that this point. So I guess this is a leak. And heard this is common issue for some bmw models. 

Signs show you have a leak on the fill up tank but not the radiator.

[Davy]

That actually looks to me like the gap between the aluminium core and the side tank of the radiator. The blue circular thing is the drain plug. So it might not be a leak in the expansion tank, but the radiator itself.

In any case, you need to get it checked out as others have mentioned. A good radiator shop with the ability to perform a pressure test should easily be able to locate the leak. 

[asier]

Recently replaced the radiator in my 318i 2003 if you have white stains on the  fan there is a high possibility that the radiator is leaking and dont fill the radiator expansion tank full..fill untill the dipstick comes up made the mistake but was lucky enough not to get the bottle cracked..still theres one hose leaking from a connection but its not consistent... im good for now..bmw's have aluminium blocks so take extra care of the cooling system..blocks can warp with some overheating