1 hour ago, TomsFocus said:

Depends how short you mean.  You could probably do half a mile here and there.  The cap holds pressure in the system.  Without that pressure the coolant will boil.  You'd be better off leaving the stuck part in the tank until you've got a new cap.

Cheers mate 👌🏼 I’ve got a new one coming on Monday, so I’ll leave it alone until then, then 😆 

Sorry just to clarify when working out the inner bit of cap that gets stuck, does it need to rotate or just be worked out vertically? 

1 hour ago, QueenlyCloud60 said:

Sorry just to clarify when working out the inner bit of cap that gets stuck, does it need to rotate or just be worked out vertically? 

Vertically.  But you may need to break the seal by twisting it first.

Hi guys. I'm struggling with this issue (on a Focus but presume it's same on various models). 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 part spins easily and feels quite loose. But, however much pressure I apply levering it out from the edge with the narrow chisel, it won't budge, it kind of flexes upwards but eventually the plastic breaks off the edge. I'm applying a lot of pressure but it won't come out. I am mystified what is holding it in?!

On 11/19/2022 at 1:23 PM, TomsFocus said:

Depends how short you mean.  You could probably do half a mile here and there.  The cap holds pressure in the system.  Without that pressure the coolant will boil.  You'd be better off leaving the stuck part in the tank until you've got a new cap.

I know this is an old forum but it’s just happened to my car, I’ve unscrewed the lid and I have battered the life out of the cap to get it out which is now ruined even the seal snapped, can I screw the lid back on and use the car normally or do I need a whole replacement before driving? 

1 hour ago, Cain1412 said:

I’ve unscrewed the lid and I have battered the life out of the cap to get it out which is now ruined even the seal snapped, can I screw the lid back on and use the car normally or do I need a whole replacement before driving? 

A wise person would have got a replacement cap before battering commenced      

 

I'd recommend a new expansion tank as well as a new cap. 🤔

Plenty of new ones on eBay for not much money.

11 hours ago, Cain1412 said:

I know this is an old forum but it’s just happened to my car, I’ve unscrewed the lid and I have battered the life out of the cap to get it out which is now ruined even the seal snapped, can I screw the lid back on and use the car normally or do I need a whole replacement before driving? 

The advice hasn't changed since that post.  The coolant will boil if the cap doesn't seal, so you can't use the car normally without a functional cap.

This happened to me a few times now, the top part of the cap seems to be poorly attached to the lower part with only 4 small plastic clips holding it in place.  It looks to be design flaw.

New caps are easily found on ebay, but all have the same flaw

 

Has anyone found a better designed cap?

 

59 minutes ago, Felix. said:

Has anyone found a better designed cap?

No but putting a light smear of Silicone Grease on the Rubber Seal should stop it happening.

When my car was brand new the Cap was difficult to take off, I did the above and when I check it every year it comes off easily.

Fixed the cap with some Gorilla Glue

Fortunately all 4 clips were still in place, so the glue had something to fix to