Freeze plug troubles

[MikeV]

I replaced a couple of freeze plugs on my 1952 Dodge engine two years ago, and now they are leaking!

its not the dripping kind of leak, it’s just weeping around the plug.

I really don’t want to drain the radiator and replace them again. The plugs that I used were round dome shaped and you had to dimple them after installation. Maybe I didn’t do it right or used the wrong sealant?

anycase I would like any input or ideas about how to fix the problem.

thanks guys!

 

[Plymouthy Adams]

while some small amount of sealant should be used, I have to ask if you got your dimple deep enough to ensure adequate expansion and proper seal

[MikeV]

Good question.  I didn’t really have any guidelines for how much to dimple the plug.

i have thought about using a AC Delco cooling system tabs (part No. 10-108)  as a stop leak.

a friend who has antique cars says it works to stop very small leaks.

anyone in the Forum who has used this product, I would love some feedback!

[Plymouthy Adams]

any product that will stop a leak....well most folks figure it is going to stop other ports in time....it is an emergency get you home product in my opinion....when home proper fix, total flush....

[Matt Wilson]

When you dimple your freeze plugs, it is really more of a flattening of its original dome shape, with maybe a slight dimpling or concavity, but not much.  You want to use a flat drift that is almost as large as the plug itself.  Hold the drift against the plug and give it a good whack with a meaty hammer.  You don't want to end up with too deep of a dimple, especially one that is concentrated over too small an area of the plug.  Creating a deep dimple is how many folks loosen up these plugs for removal, as it pulls the outside edges of the plug inward, away from the recess in the block.  I have sometimes used a large ball peen hammer as the drift, using the large (almost flat) side as the drift, not the small (ball) side.  The large side is close to being flat, while the ball side will create too much of a dimple.  I hold that hammer firmly against the plug, then whack the back side (ball side) of it with another hammer.

 

Use sealant.  Some people use Indian Head gasket shellac, others use JB Weld, others use something else.  I don't recall what I used.  It should be non-hardening.  Make sure the recess in the block is very clean and still has a good shoulder (not corroded away).

 

Be aware that there is a plug on the front of the block, behind the timing chain cover, and if it starts to leak, it may contaminate your oil.  So it's worth it to make sure it's ok.

Edited February 5, 2019 by Matt Wilson

[Andydodge]

The 5 on the dissy side of the block are 1 & 5/8th diameter, I always replace them with brass plugs, never steel and use a drift approximately 1/2" to 3/4" inch in diameter, even a large coach bolt with their large rounded head can work with the head against the plug tho hitting the opposite end of the bolt may buggar its threads...............plus some sort of non hardening gasket goo is useful so long as the hole edges in the block have been cleaned...........but as you don't want to do this again some sort of stop leak stuff should work, but isn't realy the best way but will work.............have you tried to give the plug another tap if its accessible?............regards, andyd.   

[MikeV]

Thanks to all that responded!!

some great information and I really appreciate you all taking the time to help!

I am a little confused as to whether use a steel or brass plug. There seems to be lots of opinions about that and also,  using JB Weld as a sealer. I’ll have to think that out  a bit.......

 

[Dodgeb4ya]

I use brass plugs and use a very thin smear of JB as a sealer and retainer especially on the old Hemi's, Straight eights and MolyBlock sixes.  They all  have a very shallow core plug recess and the plugs can blow out at high RPM on the V-8's.

I've seen it and this program stops that. Not that it's much of a flat head issue as the recess is deeper on the sixes.

Steel plugs can and will rust out.

Absolutely no brass issue as for corrosion compatibility either.

They must be pounded in carefully with a 3/" to 1" diameter flat heavy drift to seal/retain them properly.

Just my way of doing many of them over the years for myself and customers..

[sser2]

I tin plug's edge using soldering iron. Tin layer makes tight seal upon installation.

[Andydodge]

Sser2..........have never heard of that trick, tinning the edges but as you say it would make a tight seal......its good to learn something new every day.....thanks........andyd.

[Local2ED]

On 2/5/2019 at 3:46 PM, Matt Wilson said:

  I have sometimes used a large ball peen hammer as the drift, using the large (almost flat) side as the drift, not the small (ball) side.  The large side is close to being flat, while the ball side will create too much of a dimple.  I hold that hammer firmly against the plug, then whack the back side (ball side) of it with another hammer.

 

Two hammers should never be used to strike each other, unless of course your goal is to introduce some shrapnel into yours or someone near you body.

[kencombs]

4 minutes ago, Local2ED said:

Two hammers should never be used to strike each other, unless of course your goal is to introduce some shrapnel into yours or someone near you body.

I know you're speaking of steel hammers, and you're correct.  But, my favorite tools for this are a small ball peen held on the plug and struck with a 16oz brass flat face.  Using a hammer keeps my fingers out of harms way, the brass won't damage the steel peen and there is no rebound like steel on steel.  Only good on out of the chassis work for the most part though, most are unreachable when in the car

 except with a longer drift.  For those I've got brass drifts and a steel hammer.

[Dodgeb4ya]

Sometimes the counter bore the plug sits in is pitted....clean that counter bore carefully.

Those can be problem leakers unless done right.

As mentioned above too.... you really need a straight shot to drive the core plugs down correct and tight.

The core plugs generally never drop down into the bore.... usually they need to be tapped down to bottom them before expanding them.

[Frank Elder]

15 hours ago, sser2 said:

I tin plug's edge using soldering iron. Tin layer makes tight seal upon installation.

Like installing copper water pipe.......sweating a joint ?

[captden29]

mike, dorman makes a plug that you do not have to dimple. it goes in the blocke and it has a nut yo tighten and it expands the plug into the hole. a little sealant and you are done. part # 568-010. great for when the block is in the car and you have no room to swing a hammer. they have been in my car now for 2 years, no leaks.blowout resist to 300 PSI. 1 5/8 diameter. about $5.00 each at any auto parts store.    capt den 

[Dodgeb4ya]

50 minutes ago, captden29 said:

mike, dorman makes a plug that you do not have to dimple. it goes in the blocke and it has a nut yo tighten and it expands the plug into the hole. a little sealant and you are done. part # 568-010. great for when the block is in the car and you have no room to swing a hammer. they have been in my car now for 2 years, no leaks.blowout resist to 300 PSI. 1 5/8 diameter. about $5.00 each at any auto parts store.    capt den 

It's a copper expanding plug and they do work well seen in these two pictures... also showing right and wrong plugs for the flatheads ...

Edited February 7, 2019 by Dodgeb4ya

[sser2]

10 hours ago, Frank Elder said:

Like installing copper water pipe.......sweating a joint ?

No, installation does not involve heat. Tin (I actually use 30%Sn 70%Pb electric solder) is soft and pliable, so it fills all micro imperfections at the plug/block interface when plug is expanded with a drift.

[Matt Wilson]

On 2/6/2019 at 4:59 PM, Local2ED said:

Two hammers should never be used to strike each other, unless of course your goal is to introduce some shrapnel into yours or someone near you body.

Good point.  I was talking about two steel hammers.  I will avoid that practice from here forward, and instead use a brass hammer against the back of the ball peen hammer.  Of course, we're not talking about hitting it extremely hard, but still best to be safe.  Thanks for the tip.

[Matt Wilson]

11 hours ago, Dodgeb4ya said:

It's a copper expanding plug and they do work well seen in these two pictures... also showing right and wrong plugs for the flatheads ...

Hey, now, I used several of those rubber plugs for years and they worked great.

 

I remember considering the screw-type expandable brass plug and decided against it for some reason that I can't recall now.  I don't think the screw-type will work in the recess on the front of the block, as it will likely protrude beyond the block and interfere with the big plate that bolts to the front.  That one requires a proper dome-shaped plug.

[Dodgeb4ya]

25 minutes ago, Matt Wilson said:

Hey, now, I used several of those rubber plugs for years and they worked great.

 

I remember considering the screw-type expandable brass plug and decided against it for some reason that I can't recall now.  I don't think the screw-type will work in the recess on the front of the block, as it will likely protrude beyond the block and interfere with the big plate that bolts to the front.  That one requires a proper dome-shaped plug.

Factory type plugs are the preferred installation for sure.

The rubber expandable.....no no no.........the expandable copper plug where it can be used works good as a temporary plug for a couple years!

That's my experience?

[Matt Wilson]

Just now, Dodgeb4ya said:

Factory type plugs are the preferred installation for sure.

The rubber expandable.....no no no.........the expandable copper plug where it can be used works good as a temporary plug for a couple years!

That's my experience?

Not sure why you say no, no, no to the expandable rubber plug.  Like I said, they worked fine for several years for me, and I've heard of other people using them successfully.  The only potential downside is that they protrude into the water jacket, so they could impede coolant flow locally around those areas, but it didn't seem to be an issue. 

[Dodgeb4ya]

Being a mechanic I have had jobs where people have installed those rubber expando plugs in their engines (not on a flathead) and they popped out .... same thing on the rubber oil drain plugs getting torn out and loss of the engine from loss of oil.!

I know they can and will work but from my whole life in the automotive trade  if your'e grown up and wise better fix it right the 1st  time not two miles away from home.?

[MikeV]

I really appreciate all the good comments on the freeze plug problem.

I’ve decided to use a steel plug as I already have a couple of them. That’s what the factory probably used although, brass ones would work, but I would have to buy a package of ten and I only need one.

as far as a sealer, I think that I’ll start off with a thin coat of JB weld and then finish off the installation with Permatex # 2 around the outside of the edge’s of the  plug. I don’t think that the factory bothered to use sealant, they probably just banged them in with a drift, but who knows?

[Merle Coggins]

43 minutes ago, MikeV said:

... I don’t think that the factory bothered to use sealant, they probably just banged them in with a drift, but who knows?

 

At the factory they had a brand new block with a freshly machined surface to seat the plug into. You don't have that luxury... A little sealant upon assembly will help account for the rougher surfaces.

 

Edit: I just came across this video from Permetex, explaining the different types of sealants, and where/when to use each type.

 

Edited February 8, 2019 by Merle Coggins

[Matt Wilson]

12 hours ago, Dodgeb4ya said:

Being a mechanic I have had jobs where people have installed those rubber expando plugs in their engines (not on a flathead) and they popped out .... same thing on the rubber oil drain plugs getting torn out and loss of the engine from loss of oil.!

I know they can and will work but from my whole life in the automotive trade  if your'e grown up and wise better fix it right the 1st  time not two miles away from home.?

Ok, good info, thanks!