I'm trying to replace an old Grohe kitchen faucet with a new Grohe Faucet. We've had the original now for 17 years, and love their products!

After taking off all the hose fittings, I've run into a snag trying to remove the large round nut that goes below the brace on the underside (this is what keeps the base fastened to the sink).

While the new ones that look like a horseshoe seem easier to put on and take off. But my old one is on extremely tight, and with barely enough room to get pliers or a pipe wrench up there underneath, it's impossible to take off.

I'm hoping someone can suggest a tool or something I can use to get this off. I'm also planning to call or write to Grohe to see what they suggest.

Please share if you have any ideas.

Cheers!

If you look at the instructions of the new faucet you should find that these faucets tighten that nut from the TOP of the faucet...not from underneath the sink! Here, you usually need to remove the pull out spray hose assembly entirely ad then pull the spout UP and away from the faucet body. Once the spout is pulled up and out you will see a notched hole that takes a special tool from grohe to loosen (that or you can grab the shank with pliers and unscrew). Your new faucet should have this tool (looks like a knob with notched teeth).

Let me know if that worked out, OK?

Mark

Thanks, Mark,
Unfortunately, the old euro plus I have requires you to do it from below.
The tool with the new model is too small.

Do you have a basin wrench? Sometimes is can be easier to hold nut with basin wrench and have somebody else twist faucet(back splash or Window permitting)
Mac

I put WD40, cleaned the threads, tried it with the basin wrench. No luck. Looks like this thing is corroded on there.

Next, I will heat it and see if that works, otherwise I mAy have to take the sink out - which I really want to avoid !

Given that I have a deep sink, there's not much room to work within there - even with a flexible basin wrench.
I'm going to see if I can find a faucet nut wrench. Trip to Lowe's cming up!

Flexible basin wrench?
You will not find a wrench that will fit that nut. Best of luck but without being able to cut it out a basin wrench is your best option. Might want to confirm it removes from below.
Mac

A DEEP SOCKET may help here. You might also purchase a cheap dremel tool or a multi. tool and simply cut the nut off (please wear safety goggles if you do this). One of these ideas should work...

Mark

Rent/buy an electric hand power driver and attachment from your local hardware/and cut the nut off. Chances are when you grind/cut the easiest to reach part of the nut, it will loosen enough to twist off, or grind it until it falls off, or can be removed with a hammer or chisel. There are also attachments for electric drills and extensions for them that can turn your drill into a cutting/grinding tool. Browse and talk to a few sales guys and see what your option are.

I hesitate to recommend a small heating torch since a good amount of safety precautions have to be the foremost concern, and I would feel awful if you hurt yourself or burn your house down, but maybe a handy EXPERIENCED friend would be just the source of guidance and back up you need. You don't need to cut the bolt just heat it enough to be able to break it.

I think the hand grinder is your best approach.

Cutting it was going to be my next option. But before that I decided to go to a highly recommended plumbing store in Watertown, MA. The guys there swore by this product: "CALFONEX - Super Penetrating Pipe Break". It comes in a green can.

Sprayed it on, and left it alone for about 5 minutes.
Went back and was able muscle it loose with a basin wrench! Phew!

Got the old one off, and the new one on. Wish I could post a picture!

Thanks to everyone for the advice.

No longer 'underthesink'.