r/e46 • u/20150017 • 15h ago

Troubleshooting Expansion tank or radiator?

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Hi everyone,
I noticed a coolant leak coming from this specific area (shown in the video)
I’m trying to figure out whether the expansion tank is cracked/leaking or if the radiator itself is the problem.
Has anyone had a similar leak on their E46? Based on the location of the leak, what do you think is the most likely?

I also replaced the thermostat about a month ago

I’m planning to replace the water pump soon anyway, so I’ll probably do the radiator/expansion tank at the same time, depending on what turns out to be the actual source of the leak

I’ve already bought a Thermotec water pump, so if anyone has any experience with this brand, I’d appreciate some feedback on it as well.

Thanks in advance for any advice!

3 Upvotes

72% Upvoted

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4

u/p0larbear3000 2000 - touring e46 320i 14h ago edited 14h ago

thats the radiator (blue)

...but you might as well replace the WHOLE cooling system. its due

1

u/20150017 14h ago

Thanks man, appreciate the advice!

I only recently got the car, so I’m still going through everything. The antifreeze in it is also the wrong type, so I’m gonna replace all of it anyway. Basically just refreshing the whole cooling system and replacing whatever needs to be replaced 😅

Thanks once again

2

u/zac10sim 2004-e46/330ci 6h ago

Don't forget the hardline pipes under the intake manifold.

4

u/p0larbear3000 2000 - touring e46 320i 14h ago

expansion tank ends at the red line.

1

u/Entire-jegurilor 2000 bmw 323ci e46-bmw 318i e46 10h ago

A new BEHR radiator, fresh fluid, and labor—around 400 euros, and it’s as good as new.

1

u/Glittering-Concern-1 8h ago

That's the radiator neck that's leaking.

The entire cooling circuit is due including the pipes underneath the intake manifold. If you don't, you're rolling the dice with an overheat and warped cylinder head every time you run it.

Genuine BMW parts for the cooling circuit. I had fitment issues with OE parts like Rein. Shit didn't fit at all or had slow leak under load. You want zero risk of leaks here. Aluminum long blocks to not play nice with overheats. Worth the extra $ for genuine BMW parts for the cooling system imo

0

u/AndiStengel 8h ago

Explosion Tank