Freeze plug replacements

[Jeff Balazs]

Hey Gang;

I have a weeping freeze plug after close to 5 years of daily use. When I put these in during my build all I could find were the steel type. It seems to me I saw afterwards some brass ones and maybe even some expandable alternatives. Since I have to deal with this I thought I would ask what others have done and get some sort of discussion going on the topic. A buddy of mine that is really familiar with early Hemis thinks they used the same type of freeze plug and the L6 engines. If that is the case and if by chance they are the same size there are a couple of different types of aftermarket freeze plugs that have been developed over the years for the Hemis. I am wondering if anyone has knowledge of these and knows if they are a good fix for our flatties?

 

Thanks, Jeff

[Tooljunkie]

I used a rubber expanding one, because i was stuck. Think i have to backorder a box of 25 to get one. 
the plug has to fit the shoulder below the existing plug or it pops out when you snug it up. Its holding fine with my 4 lb rad cap. 
it was $7.50, cheaper than a box of 25,and i would still be waiting for it. 

[Los_Control]

On my 1949 218, the plugs are 1,5/8" and found them at a local car quest parts store.

They gave me a option for steel or brass, so I chose brass.

 

Then later, I read where someone suggest brass is a bad idea because of dissimilar metals.

The brass will not corrode out, so the block will actually be the weak link and start corroding.

 

If this is true, dunno. But it does make sense to me, The plugs would be a lot easier to replace instead of a block.

There seems to be no definitive answer on this though. Mostly just opinions.

 

My opinion is leaning towards,  The brass will work great for the 20 or 30 years we use these engines. But since they are now 70 years old, if they had brass soft plugs from factory, 70 years of time may cause a issue with the blocks.

I am thinking I may replace my brass ones with steel. Let the next caretaker have as much fun as I did replacing them 

[kencombs]

W

-Steel, when used with good coolant, should last longer than the engine.  Most of them rust due to inadequate anti-rust in the coolant, diluted too much with water or water with too many contaminates.  Brass is available, but at a premium and I just don't see the value.  Installation, proper prep on the recess and sealer are much more important.  If I see any hint of pitting in the block at the seating area, it gets a little JBweld instead of Permatex.

[Pete]

I'm currently getting my '39 Plymouth engine rebuilt. One of the reasons is that the freeze plugs were just starting to leak a bit. They were steel. The rebuilder told me that dates stamped into the various internal parts indicate the engine was last rebuilt about 1950. I'd say the steel plugs work well if you take care what you put in the cooling system.

 

On another note, the brass water distribution tube came out looking almost brand new.

 

I've also heard that brass reacts with aluminum, but not with steel or iron.

 

Pete

 

[HotRodTractor]

I just replaced a freeze plug on the P15. 1-5/8 concave. I went with steel because that was what I could get quickly. Less than $10 for a box of 10 if I remember correctly.

 

I do have to pull the motor this winter and I am going to replace all of them as I have a couple others that show signs of weeping. I'm also going to put something around them to seal them up a bit better to the old cast iron - not sure if I am just going to go the route of some gray rtv, or more extreme and put a thin layer of JB weld on the lip and seat them into it. I am pretty confident that they will last significantly longer than I need them to if they get sealed appropriately. The ones in the engine aren't rusted, but they weep around the lip, stop that and all will be well.

 

 

[JBNeal]

are the freeze plugs weeping at the perimeter or have they developed a pinhole somewhere in the face?  Before I thought to use some sort of sealant when setting them steel freeze plugs on my builds, I was advised by several older mechanics to just use some thick yellow axle grease to seal it...this was their go-to sealant back in the day, to stick cork gaskets in place and whatnot...so far, I've had one steel freeze plug weep using the axle grease seal, but the modern sealants should be more effective...as far as I know, the freeze plugs are designed to fail to relieve any excessive pressure in the block water jacket to save the casting, kinda like the concave bottom of a coke can is supposed to pop out when a soda freezes.  I have found out (the hard way, of course) in recent years that aging coolant becomes acidic and accelerates cooling system corrosion and component failures.  When the manufacturers say to flush and fill with fresh coolant every 2-4 years, they ain't kidding...I've had to deal with blown head gaskets, leaking water pumps, and in diesel applications, erosion of the head passages that have caused some nasty $$$ problems, on engines where the coolant wasn't touched for years...the coolant was still green, but when repairs were required and a coolant flush was performed, all kinds of gunk blew out of the system, on engines used daily.  It learned me and my neighbors in distress how cheap a coolant flush is compared to deferring maintenance, that's for sure...so if you've got some corrosion showing up on them freeze plugs, you might have another impending problem that ya might be able to head off if you catch it in time

[Tooljunkie]

I agree, i use a universal long life, good for 5 years. A flush really isnt necessary,drain and fill with fresh will replenish the corrosion inhibitors and water pump lubricant. 
flushing would be necessary if coolant is causing sediment to start forming. 
just had a 15 year old  truck in for that very reason, plugged the heater core. That stuff is nasty. 
 

chrysler now has 10 year coolant. Purple and expensive. Its fiat engineering. 

[kencombs]

Often misunderstood are 'freeze plugs', in my Yoda voice.  Called freeze plugs in common discussion by most everyone.  Core plugs is the correct name and describes their real purpose, which is to remove the sand used to build the casting core pattern. 

 

I've seen them push out of an engine that had the coolant frozen.  I've also seen very long cracks, full length of the water jacket below the level of the plugs. 

 

Was taught long ago to use Permatex, either #1 or 2 as a sealant on them.  If I see any evidence of a imperfect block hole due to chipping or corrosion, it gets a bead of JBWeld in the bottom.  Never have had a leak on one that had those treatments.

[HotRodTractor]

At least in my case its perimeter weeping. The plug I took out looks fantastic - other than it leaked around the outside.

[Jeff Balazs]

I think it is a perimeter leak. My truck sat with water in it for a long time before I got it. Everything was in pretty fair shape other than the cooling system. It was about as bad as it gets. The WDT was totally rotten and getting it out was one of the worst jobs I ever had.

The block was full of junk. I flushed many times before and after I put it back into service. I even put a brand new Desert cooler radiator in it about 1 1/2 years ago. And of course fresh coolant. There could and probably is some scale and crud behind the lower plugs. There is another than shows signs it is beginning to weep. I have new plugs coming and will replace once they arrive.

The reason I started the thread was to see what others had found for long term replacements. I know that there are aftermarket 2 0r 3 piece plugs that were developed for the old Hemis.......was thinking these might be a better solution but I don't know much about them or even if they are the correct size. Was hoping someone here knew or maybe had another quality type fix.

Jeff