Odd one here, (the problem not me) I went to check the strength of my anti-freeze, so started unscrewing the cap of the expansion tank. It unscrewed easily then started to get stiff, so much so that I’m unable to get the cap off. When turning it back on it’s nice an easy again, but just will not come off. The engine is cold when I try. It’s a Focus 1.0 Ecoboost, 2018 plate.

Am I missing something?

Thanks

The inside part of the cap is stuck, it's a very common problem.

You just have to keep trying to unscrew it, work it backwards and forwards and don't be afraid to use a bit strength. The cap will be broke so don't think about trying to save it.

You can get a brand new one from Amazon or eBay for about £5

 

When mine was stuck I managed to get it off by heating up engine and undoing cap because the pressure in the coolant reservoir helped push the stuck part free. BUT be careful, there is a danger of steam, scalding water being released. BE CAREFUL

Thanks, for your advice. 

Hi guys, reviving an old thread as I'm struggling with this issue. I used a narrow chisel to lever off the bottom section of the old cap (I'm not bothered about breaking it, I've bought a new one). This brought up the seal then I pulled the seal out, now the lower (remaining) part of cap spins easily and feels quite loose. But, however much pressure I apply levering it up from the edge with the chisel, it won't budge, it kind of flexes upwards (flexing the tank a bit too) but eventually the plastic breaks off the edge of the cap. I'm applying a lot of pressure but it won't come out. I am mystified what is holding it in?!