LS freeze plug issue

[K5Rob]

My LM7 i am using for my K5 swap has a freeze plug issue. I pulled the motor this past weekend and it’s on the stand. The donor truck was my semi daily driver. It had the 706 heads which developed a crack, I noticed quickly and replaced with reman 862s. I had a machine shop “give me their blessing” before installing them. Bank 2 rear plug developed a leak at some point years ago. Its buried against the firewall so I cleaned it real good and smeared JB weld around it to attempt to stop it from getting worse. It worked and held for all this time although now that I have the motor out appears it may have begun to start dribbling. Wondering what you guys think is a good course of action now that the motor is out. Obviously want to try a new freeze plug but worried maybe the hole is out of round or something. All others have been fine. It’s a good motor with only 100k on it which I’ve owned most its life. I am going to regasket the motor but would prefer to leave the heads alone. I can get a bottom end gasket kit cheaper if I leave the heads out of the equation. There Mahle MLS gaskets and GM bolts on it now. Trying to stick to a budget. What are your guys thoughts?

 

[Vbb199]

Knock the freeze plug out and replace it ! Better safe than having to pull the motor back out later on

 

[TotalyHucked]

Yeah, I think you're overthinking this. Get a new freeze plug, knock the old one out and knock the new one in. The chances of the hole being out of round are very slim. And if it is in fact out of round, deal with it then. Won't know till ya try

 

[Snoots]

Use a BRASS freeze plug.

 

[K5Rob]

Sounds good guys. Yes definitely will get a new freeze plug. So you think it was just installed wrong? Or should I try to stake it off somehow

 

[Drauka99]

know some who when reinstalling a freeze plug in situations like that us a thin application of rtv on the rim of the new freeze plug to "gasket" the plug for imperfections

 

[Chugalugg]

know some who when reinstalling a freeze plug in situations like that us a thin application of rtv on the rim of the new freeze plug to "gasket" the plug for imperfections

I always used a smear of Permatex #2 on the brass plug/block because of a chance of an imperfection. But that was on an iron block though. Never had a leak, so far.

 

[K5Rob]

I always used a smear of Permatex #2 on the brass plug/block because of a chance of an imperfection. But that was on an iron block though. Never had a leak, so far.

Is permatex #2 the brown aviation sealer? If so i have some. This is iron block, alum head. I got brass plugs as suggested and they are on their way. Its got brass in it now. It does look that there may be an imperfection. Still chipping away at the jb weld. Wondering if a high temp rtv would be a better choice. I feel like that permatex #2 may eventually wash away since it never hardens

 

[Chugalugg]

Thats why the #2 is a good choice for freeze plugs you can have a bit of movement and still seal and yes, it's the brown stuff. If you have some it's really good and kinda sticky. But if you are chipped up, IDK if it will seal properly? How did the chips in the iron happen?

 

[Drauka99]

How did the chips in the iron happen?

If I guessed I’d say rust pitting from a slow leak for a long time before it got bad enough to be discovered.

 

[JBswth]

My LM7 i am using for my K5 swap has a freeze plug issue. I pulled the motor this past weekend and it’s on the stand. The donor truck was my semi daily driver. It had the 706 heads which developed a crack, I noticed quickly and replaced with reman 862s. I had a machine shop “give me their blessing” before installing them. Bank 2 rear plug developed a leak at some point years ago. Its buried against the firewall so I cleaned it real good and smeared JB weld around it to attempt to stop it from getting worse. It worked and held for all this time although now that I have the motor out appears it may have begun to start dribbling. Wondering what you guys think is a good course of action now that the motor is out. Obviously want to try a new freeze plug but worried maybe the hole is out of round or something. All others have been fine. It’s a good motor with only 100k on it which I’ve owned most its life. I am going to regasket the motor but would prefer to leave the heads alone. I can get a bottom end gasket kit cheaper if I leave the heads out of the equation. There Mahle MLS gaskets and GM bolts on it now. Trying to stick to a budget. What are your guys thoughts?

Replace it and the others while you have the motor out. You don't want to have to pull it again, and use brass plugs. They are better.

J. B.