Corroded expansion tank

[The Surveyor]

Doing some under-bonnet checking over the weekend, noted that there was quite a bit of corrosion on the outside of the expansion tank. Took it off to clean and discovered that the rubber hose was blocked and there was a lot of debris in the bottom of the tank (no wonder the water / antifreeze level never moved).

Once cleaned out, there were several tiny pin sized holes through the alumnium, so i will eventually need a replacement (the plastic-metal repair seams to be holding) but is this a common problem! The antifreeze concentrate looked fine btw.

Fully flushed the system and refilled using correct antifreeze concentration, but does anybody know how much a replacement expansion tank will be.

Thanks

Paul

[GreenV8S]

No that isnt normal. If the tank has corroded so severely, I would be concerned about the state of the rest of the engine. It's all alloy and vulnerable to corrosion if you don't keep the corrosion inhibiters up to strength.

[The Surveyor]

My thoughts exactly. I stripped the swirl pot off to check, and that was fine and had a good strong antifreeze mixture in the water, no sign of corrosion, so i'm hoping that this is limited to the header.