I have a couple of freeze plugs that have started weeping. Does anyone know of a sealant I can use to stop this? I just started building a new engine for my truck so I only need to get to next spring when I swap the engine.

 

You may want to rethink this.

Any gloop that stops a leak can also plug a radiator and heater core.

 

Oh I should elaborate, I don't want to put something in the cooling system I want something I can use on the outside to seal the freeze plugs. Cooling system stop leak is the reason I'm in this position. The previous owner put in more stop leak than I ever thought possible. I've flushed the cooling system 6 times and I'm still getting stop leak out of the engine. I think the freezer plugs are weeping because of all the cleaner I've used. I was told that stuff doesn't do the sealant on the plugs any favors.

 

You know the system is under pressure and I doubt any form of glue will hold around a plug.

 

Is it easy access to just change the plug that are leaking?

 

You need to find out what is making them weep. Perhaps they were maltreated or abused by a previous owner.
Maybe they feel that they are really male plugs trapped in female bodies and so are having a gender identity crisis.
Constant weeping from the engine should never be ignored or belittled as it can lead to resentments and lost trust between the two of you. Let it know you love it and that you will help it through this crisis whether it be feelings of hurt or a voyage of discovery of its true gender identity.

All the best to you two, I know you can patch things up.

 

Freeze plugs are made from steel which can rust. On old engines when a plug gets rusty enough coolant can start to weep right through the metal. That's what you may be seeing. Only replacement will fix this.

 

Since the engine only needs to last until next spring when it will be replaced, I would just keep topping up the coolant, and add a can of stop leak.
Many wrecking yards give away or sell used coolant very cheap, just get a couple jugs of this.