As you know, there's a petcock at the bottom of the radiator on the passenger side,
and the coolant is slowly leaking there on my car.

I've searched about petcock leak, and all I've found are:

1. replacing the petcock is not easy because it's not a normal screw and in the worst case a part of it is left inside the radiator when pulled out.

2. there's no replacement seal available (especially when you cannot take it off)

What do you think is the best way to stop the leak there?
Do you think a liquid type anti-coolant sealant works?

 

dorman 490232 or acdelco 3056858 ,you can't buy the washer and petcock separately if that's what your asking.

 

What is the safest way to replace the petcock?
I know there's a replacement petcock, but to replace that I need to take out the whole petcock parts safely, with nothing left in the radiator...

 

Why is it snapped off ? It has plastic threads and unscrews . Unless its so brittle the ears snap off it will unscrew you can catch all your coolant and now would be a good time to change it I'm sure. Or remove it quickly and install a new one. tie a rag around your arm or be quick lol

 

Even if the two ears pop off into the radiator no need to fish them out the should come out as the coolant is hitting you in the face or going into your arm pit. The peacock doesn't hit the other side of the tank if your thinking it bottoms out.

 

If replacing the petcock is an easy work, that will be the best choice.

Has anyone ever tried replacing it? Has anyone had any trouble doing that?

 

the only option is to replace the petcock. just unscrew the old one and install the new one. the biggest issue here is not the petcock, but the bung in the radiator that it screws into. once it gets stripped, the petcock will no longer seat properly and won't seal. if that's the case you need a new radiator anyway.

 

It looks like I cannot take the whole out once it goes into place.

 

I have a similar problem as OP. Except, I took out the whole peacock in one piece. I can see it has a ring of RTV/sealant on it but some of it has came off which is causing mine to leak every time I try to keep adding coolant.

 

I have a similar problem as OP. Except, I took out the whole peacock in one piece. I can see it has a ring of RTV/sealant on it but some of it has came off which is causing mine to leak every time I try to keep adding coolant.

Edit: never mind it wasn't one piece.