Garage door lintel scary

[elcaro]

hi all, the concrete lintel over my garage door has a bit crumbled off it. Photos show the damage - you should be able to see the rebar visible for a few inches. Above the lintel is a bit of a decorative wall of a couple of courses. The exposed concrete feels slightly crumbly.
Have I got a small problem, a medium problem or a disaster-type problem? Any advice? I don't want to spend a lot because ideally I'd knock the garage down but it shares a wall with next door's garage so PWA would rear its ugly head.
I'd be grateful for any advice
Regards,
Terry

 

[tony1851]

Looks like it's concrete cast around a steel beam. Once the steel rusts and expands, it forces chunks of concrete off - inevitable really.
Not going to collapse overnight, but a problem for the medium term.

 

[elcaro]

Thanks Tony. It's not clear from the photo but it looks like what's visible is a bit of reinforcing wire / bar rather than a beam, but yes as you say the rusting will force concrete to break off. If it is reinforcing bar then maybe not as strong as a beam , dunno. Can I bung it up with something as a temporary measure? I don't think I've ever concreted upside down
There's a wooden piece runs alongside it (in bottom half of third photo, which was taken looking upwards) so I could screw a bit of shuttering onto that maybe? Or maybe there is a special "sticky" cement product available? TIA, Regards, Terry.

 

[Grantx]

My opinion: that wood is the original lintel. Via shuttering, the concrete has been poured in front and above the timber to form the parapet (and, effectively, the outside lintel). The steel reinforcing has blown through rusting due to being too close to the inside surface of the concrete, and thus the concrete touching the damp timber lintel. Patch it up with mortar, it's not going anywhere.

 

[elcaro]

thanks Grantx I'll do that.
Tony, Grantx, thanks for your help. I don't want to spend more than minimum time or cash on this cos my preferred answer if only it wasn't attached to next door's garage would be to knock the whole thing down!