Monoblock clamp holding basin tap is totally stuck. What now?

Andrea15

Hi,
my bathroom tap was never properly tightened using the horseshoe shaped monoblock tap clamp that goes underneath the basin and is tightened, making sure the tap doesn't swivel, using the appropriate monoblock tap spanner. I hope you know what I am talking about.
My problem is that 10 years of leaks have made sure that I cannot undo the bolt that holds the clamp in place, no matter how hard I try.
Assuming you can picture the situation, what can I do? Usually the threaded stem that holds the nut in place has a slit where you can put a screwdriver in, but not in this case. Now the plastic between the clamp and the sink, already very corroded, has all but disappeared, so the tap is very loose, but the bolt won't come off.
Ideas? I have already put WD40 like there is no tomorrow, but no joy.
Shall I buy a new basin?

Browntoa

I take it you cannot get a hacksaw blade under the tap 

TadleyBaggie

WD40 isn't a lubricant, it's a water displacer. Try some penetrating oil.

Paula_Smith

Drill a hole in the clamp then prize it apart - you will destroy thr thread on the tap but I guess you are expecting to replace it anyway.

DiddyDavies

TadleyBaggie said:

WD40 isn't a lubricant, it's a water displacer. Try some penetrating oil.

"standard" WD40 is a penetrant, water displacer and lubricant.
Other WD40 products are geared towards more specific purposes but the normal everyday WD40 does have lubricating properties.

molerat

What are you using to undo it ?  Usually a box spanner with a decent amount of leverage on the long nut will get it moving.

Andrea15

Thanks to my super strength I have managed to shear the stem just above the nut, so now the tap is free. Now I should try to remove the stump of the stem from the tap itself. Now sure I will manage it, thou. I have tried grabbing hold of it with some pliers, but I am not getting very far. I wouldn't want to have to through the tap away as it is perfectly good.
@molerat, yes, I am using a box spanner.

macman

Something like Plus Gas will do this kind of job far more effectively than WD40.

nofoollikeold

1. Drill into the centre of the screw stuck in the body of the tap.  They are usually M6 threaded rod, so drill 4.5 mm.
2. If you have one, use an "easyout" to get the rest of the threaded rod out.  If you haven't, try jamming the square end of a file shank into the hole you have made and turning it.
3. If you are really good with the drill and can start it and keep it central,  drill through with a 5 mm drill and re-tap M6.  
4. Use brass threaded rod as a replacement.
5. With all the above faff, and particularly if you haven't got the tools, replace the tap.

flashg67

a stud extractor, as used in garages will likely do it, but a new tap may be cheaper!

Andrea15

Yes, I suspect it might be to much faff to salvage the tap. I see they can be quite inexpensive, so no huge deal. Tomorrow morning I'll go to the merchant to have a look. They may be able to extract the stuck stem, who knows