I recall once talking to a former mechanic about freeze plugs and he said to use steel plugs rather than brass but I can't remember the reason. I would think that brass would be better for their non-rusting quality. Also, is it better to apply a sealant like Permatex when installing or put in dry. Any suggestions will be appreciated. The engine in question is a Mopar 318. John
If you intend to neglect the cooling system maintenance, then you want brass freeze plugs. If you'll take care of the engine, then it doesn't matter. yes, use sealer around the plugs, and clean the holes well, so they won't leak.
That's the way I have done it for decades. Brass plugs , clean good and apply sealer all around the cup edge.
With the different metals of brass against cast iron, the iron will sacrifice itself to protect the brass, as it's higher on the "electromotive scale". If the cooling system is kept in good condition with proper antifreeze, it shouldn't matter. I have noticed it is sometimes hard to find brass plugs in the shallow OEM design, only deep ones being available for some engines. These don't look so nice if they protrude from the cylinder block.
Freeze plugs?? What the hell are freeze plugs?? You must be talking about Core Plugs. Those plugs are there to allow sand cleanout from the casting process. Only. Squirrel is correct on all points.
I was wondering when we'd get back to the "core plugs, Welch plugs, and freeze plugs" side debate. Popcorn anyone?
In Chicagoland they are called freeze plugs. Always have been. Never heard them called core plugs. If you ever had an engine start to freeze up in the cold, the freeze plugs will pop out buying precious time before the block cracks.
The whole , frost, freeze, Welch, casting, blah blah blah. We all know what he’s asking about ! Sheesh ! Lol And like squirrel said clean clean clean I use loctite flange sealant .
Are you a retired GM engineer? I was wondering if you have any advice, Manifold or Ported vacuum for my distributor. Thanks!
I froze a Ford 300 six one time after my dear old dad told me it was going to get cold and I better check the antifreeze in my truck. When your 17 your dad knows nothing and your a genius - guess what happened. It froze solid and I never noticed the frost plugs pop out - but when I took the head off - the cylinders were cracked an busted. My question is has anyone seen frost plugs pop out and save a engine?
TomA to,,,Tomahh to,,,,who cares,,,,Lol. I bet that the guys from overseas that are on here laugh like hell about our arguments about something as trivial as this! But,,,,I always get a kick from the comments about it!!! I think one guy recently explained it as Smartasserie,,,,,I really liked that adjective! Or would that be a descriptive adjective? ,,,,,oh no,,,,I think I just started a new argument! Tommy
Sometimes you get lucky and one will pop out, despite what almost everyone says they were never put there for protection from freezing...as said they are for being able to remove sand from the casting process. But terminology is only important to some people when it suits them. Tell they same people who say it doesn’t matter that they have a nice rat rod and I bet the terminology matters then. Sent from my iPhone using H.A.M.B.
I never realized they were there to remove sand from the casting process ,it sure makes perfect sense. Everybody has always said freeze plugs are there to help if and engine freezes but they seem to do a piss-poor job at that!
A lot of modern engines don’t have them anymore at all due to different casting procedures. Frost or freeze plugs is one of those things that is technically incorrect but continues to get passed on. Sent from my iPhone using H.A.M.B.
Freeze plugs? Core plugs? Yep, one of them.... I've had lots of 318s, as for the "plugs" protecting the block from freezing, the odds are not so good, probably less then 25% to the good. My guess would be that getting the sand out of the block after casting may have been pretty hap-hazard, sometimes I've wondered how effectively that really was really done. I've replaced a lot of freeze/core plugs and have dug out a pretty large amount of sand in the process. I also have discovered that when one plug rots through, more will follow very soon. Seldom have I gotten away with just changing one plug. When I took the short cut, and the 2nd one rots through, I usually change the rest of them. The worst two are the two at the back of the motor inside the trans bell. Also, after I pull out all the old plugs, I scrape out as much of the crud around the cylinder walls as I can, then flush the block with water until it runs clean. Then I reinstall new steel core plugs with sealant. I don't ever recall having to change a second set of core plugs in any motor that I've every replaced them all and cleaned the block out of. Changing all the core plugs is a pita when the motor is in the car. Gene
Water is good stuff.. It is practically unique in that it expands when frozen, almost 10% and it floats. But it doesn't necessarily expand the way one might think. Fill a glass bottle halfway, and notice it might break in subzero temps, even though there's all kinds of room for expansion in the upper half. That's why freeze plugs don't do anything inside the coolant passages to protect an engine block, that isn't what's going on inside at all.
I always thought the expansion plugs popping out was an indicator of a cracked block, or a cracked head. I just had a 454 equipped pickup given to me, that has one out. The owner told me three different stories about how it happened, until he finally settled on the truth.
Put a fresh rebuilt 396 in a 56 chevy one time. Put straight water in it for the break in run. Later that day, a bunch of friends stopped by and said they were going camping for the weekend. Hell yah I went. About an hour away. The next night, about midnight, it got real cold real quick.. Then I remembered the chevy in the unheated barn. I left for home and when I got there I saw two freeze plugs on the ground and ice turds growing out of the core holes. It was not solid ice but more like a stiff slushy drink. I thawed her out and had no damage to the block at all. Beat that engine for years and always thought how close I came to losing it.
I've seen who knows how many cracked blocks in the past 60 years and have yet to see one that had the freeze/core/soft/welch plugs be pushed out that I can remember. One of the last ones I saw was a 400 Mopar that a couple of my students drug into the high schools shop to thaw out in the middle of winter and the block cracked to the inside of the crank case and the melting coolant pushed the oil out the breathers. There was one hell of an oil slick on the shop floor the next day. Brass plugs have always been a boat thing especially with engines that are cooled by salt water running though the cooling system that don't have a closed cooling system. It's standard procedure to use brass soft plugs on marine engines no matter how they are cooled though. There may be a tiny bit of electrolysis with the brass plugs but it wouldn't be any more than with brass pipe plugs in the threaded holes of the cooling system.
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