The Stovebolt Site Forums The Shop Area Engine Shop How do you put freeze plugs in?

I’ve never seen this subject addressed here so I thought I’d ask. Over on another Chevy forum someone posted that you should hit the lip edge with a socket with the rounded lip squared off or a special tool. To do otherwise may cause the plug to leak. Just curious how others have approached this job while engine is in truck. Not worried about the others, just the bottom of block. Thanks.

Freeze plugs are typically a bit oversize for the hole, so using a socket that fits either inside the edge or on the edge would work. The way it's designed is the edge has a bit of spring to it and seals with the elasticity of the steel. Put some sealant on it too to be sure it seals.

I use permatex form-a-gasket on the edge, then drive them in using a socket that fits inside the freeze plug. Drive it in till the edge of the lip is even with the outside of the block. As Kevin said, the lip has some spring in it and it should be a snug fit.

Are you talking the flat plugs or the cup plugs?

As been posted, with the "cupped" freeze plugs I put a little coat of aviation permatex and/or Super 300, or similar around the outer cup, use a socket that just fit's inside the cup and drive it in as evenly as humanly possible. As also stated drive it in until the outer edge of the cup is even with the casting it's being driven in to.

On the slightly dished type freeze plugs that aren't cupped, I still like to put a little coating on the outer edge, then gently and evenly start the plug into the hole with the dished part (convex) facing out. I also use a socket that almost matches the size of the plug but will fit into the casting. Most of these type of plugs are driven in until they bottom out on a race or shoulder. Once fully driven in, take a ball peen hammer and place the peen end in the center of the plug. Using another hammer strike the ball peen hammer so it will indent the center of the dished plug inwards. This has the effect of expanding the plug outwards, making for a tighter leak proof seal. Don't go gorilla on it tho, try to match the dish to the same dimension as the one you removed.

Dave

Happy to know that your procedure is about the same as mine, given I can get to it. I just don’t/didn’t use any kind of sealer. Now we would like to know how you would do it with the engine still in the truck and you...1. don’t have a ‘straight shot’ at the plug, 2. you can’t get a hammer into the tight confined to hit the socket. I used a air chisel with a large flat surface bit with lots of tape over the face. I turned the air way down to lessen the impact and worked the bit around the lip edge until the plug seated. Also used brass plugs rather than steel. How crazy is my ‘hillbilly, get ‘er done’ procedure?

Great post Dave, and I install mine like you do. It has to be said though, for a freeze plug to do its intended job, they shouldn't have adhesive on them, so they can easily pop out if you freeze that coolant/water. You will probably crack that block before they pop out with adhesives. With that said, I subscribe to adhesive because the ability to seal outweighs the freeze protection. We love our bolts and we run the correct water/coolant ratio so there shouldn't be a problem or the need to guard against ignorance.

Steve

I agree with sstock’s first statement. Sealant, I would think, would negate the purpose of the freeze plug. We I popped the original factory plugs out, I saw no sealant.

I disagree on the sealant keeping the freeze plug from popping out if a freeze-up were to happen. It's the path of least resistance. Ice formation has the feature of the last spot to freeze is the one that breaks due to the ice around it preventing the expansion (water to ice) from releasing. So if the freeze plug freezes first, the block is going to crack anyway.
That being said, "freeze plugs" are actually core holes for casting the block, and freeze protection is secondary to being able to get the core positioned for casting and the sand out after casting. The plugs primary function is to keep coolant from leaking out of the core holes.
I say seal them up. They're more likely to leak because of corrosion that fail to pop out if a freeze-up happens.

And don't forget for emergency repairs or for repairs where clearance is a problem (essentially when an exhaust pipe, steering box, fan belt, water pump, etc) prevent you from reaching a plug you can use the rubber expansion plugs. I used one on a GMC with a 228 and forgot about it for over 2 years (it was in front of the engine where there simply was no room up there). No problems with it at all.

I like that air chisel idea...
Good job, hillbilly. LOL

A friend tried one of those rubber expandable plugs on his MoPar six, after it built up pressure during the warm up test it popped like a giant high priced wine bottle, bent the inner fender and sprayed his brand new anti freeze all over the truck and surrounding area, he figured out a way to get a steel one back in, LOL.
Dave

Ive used the rubber freeze plugs a time or two with good results. The catch is you have to tighten them up tighter than you think you should. Then alitta tighter if you know what I mean? On the other hand, find a socket to fit the metal type freeze plug and try to get it in square as possible without distorting. Practice makes perfect..

Other than the final repair looking a little "redneck" there's nothing at all wrong with using a rubber expansion plug as a replacement in tight quarters. Install it "dry" and tighten it well- - - -sealer will just lubricate it as it pops out. Anyone who is critical of that procedure is welcome to show me how he would do it- - - -I'll watch and learn!
Jerry

To date, have not had one fail in service.

When rebuilding the engine, I would always replace ALL core plugs (as Kevin mentioned, freeze protection is a secondary function).

For a driver for the convex plugs, I would start with a piece of brass bar larger than the diameter of the plug, and turn down the end on the lathe to be slightly smaller than the diameter of the core hole, and flat on the end. This allows force to be applied in the very center of the core plug, and gives the best expansion. And no, I don't use sealer.

I use the same method on carburetor core plugs.

Jon.

We make up drivers with a tiny step and a stop flange. The step seats the plug exactly even with the chamfer and the flange squares the plug in the hole IF the casting is smooth. We use the rubber plugs on crack repaired blocks so no stress is exerted to restart the crack.

Evan- - - -what's your opinion on repairing exterior cracks from freezing- - - -any downsides? I prefer the "sewing" method where a series of overlapping threaded plugs seal the crack. In places where there's no combustion chamber pressure present, I've had very good luck with that type of repair. It's expensive to tool up for the first repair with the drill bits, tapered reamer and threading tap, but after the first repair it's fairly inexpensive to do.
Jerry

FWIW I had long thought of these as freeze plugs until some automotive machinist told me that they served as core plugs so sand could be gotten out of the casting at the factory. I have seen too many of these blocks that froze and cracked without moving the plugs. In my youth I worked in a welding shop where the boss welded and or brazed many cracked blocks. He had a big oven to put the blocks in before welding.