Freeze Plug question

[Don Jordan]

It's 98 outside how could I have a freeze plug question?

Thought I would go for a harmless drive to the bank. 2 miles from home I noticed the temp gauge going up. No BFD - I pulled over, I carry 2 gallons in the trunk. I put both gallons in and it didn't fill up. This is a problem when you're not thinking about what you're doing. Drove a few blocks to a gas station and started putting water in - would not fill up. Okay now (finally) I'm curious. Someone left a big round hole in the side of the engine - water was pouring out. I know this was stupid but I made a run for home. 2 miles, down hill.

That was background - here is the question: Could the freeze plug have blown out because the radiator cap was rated at too many pounds? What would cause this? The whole thing is gone.

Question two: the parts store had 2 kinds of plug - one was brass that you hammer in one was rubber with a nut on it. Is anyone better than the other?

I'd like to sneak one last question - the temp gauge peaked and isn't coming down - did I break it?

I tell people I'm really unlucky (that this happened) but I'm really lucky at it (that I at least made it home).

[cole18cars]

I blew out a core plug the other day.It was one I had replaced about a year ago. I started the engine to check my carb, but the temp wasn't high enough to open the thermostat fully I guess. I reved the engine, and the next thing I knew I had antifreeze all over. I think the pressure from the water pump going thru the small recirc tube was too much. I replaced mine with the rubber and nut type. Could be removed to flush the engine.

[Plymouthy Adams]

the correct plus is slightly convex...not the cup-style plug...these are insered dome out and dimpled..recommend a tad of permatex #2 when installing..IF you shold go with the rubber style...these will work but please take note that they are a tad thick for the block on these engines...I suggest that you carefully slice this puppy in half and install..that way you get a spare rubber...I did this long ago on one of my engines as getting a hammer in the compartment was just not possible...

[Jerry Roberts]

For another solution google Dorman 568-010 . It is a freeze plug made from brass , steel , and copper with a nut on the side for tightening . Works great in tight spots . I used black RTV sealant on mine .

[Don Jordan]

I was checking the Plymouth service manual and it's interesting that I could not find any mention of freeze plugs.

I bought a brass one but it has a lip on it about 1/4" and I don't feel confident it's the right one. I bought the rubber one but like it's been mentioned it won't fit into the hole flush.

I can see rough cast iron inside the freeze plug hole but I don't think it was meant to be smoothed out.

I was also reading and learned something: "The pressure vent type radiator cap was introduced in the middle of 1950 on Plymouth cars."

I'll tackle this tomorrow.

[Don Coatney]

These are called "welsh" plugs.

[randroid]

Don,

I've blown two 'freeze plugs' (they are called that but have nothing to do with freezing; another thread) and replaced them with the rubber ones with the nut for tightening because, as Tim said, you can't get a hammer to them. I'll replace them with the correct ones when I pull the fenders for painting and in the meantime I'll check-out those Dormans Jerry mentioned.

The point of my post is that over the life of your engine you're probably not the first person to replace a plug, ergo not the first person to apply #2 Permatex, and I think the holes were machined for a tight fit, so whatever plug you use you'll want to scrape the mating edge absolutely clean of old sealant and scale. Easier said than done but the edge of a screw driver and scraper will get the job done, and you want it done right the first time or you'll get to do it again more than two miles from home.

And yes, you tooled your guage just like I did mine. Wally World has a $10 replacement that will work until you're ready to fork-out the bucks for an OEM guage (about $125). The guage operates with a "Bourdon tube" which is that crescent-shaped brass thing in the guage. As temp increases the ether in the capillary tube expands and tries to straighten the tube, thereby pulling a rod attached to a linkage as simple as our throttle linkages that eventually moves the temp needle. You should spend a few hours attempting to tweak everything back into place because after you learn you can't adjust anything that will make it work (you stretched the Bourdon tube and you can't un-stretch it) you'll be more willing to fork-out the bucks for the OEM.

Good luck.

-Randy

[randroid]

Don,

Okay, I just checked-out the Dorman 568-010 and that's what I used as a replacement and they've done well by my engine, but if I had my druthers, I druther use the Welsh plugs and carry a couple Dorman 568-010 just in case.

Observe Mr. Coatney's digital caliper reading 1.6265". ! 5\16" = 1.65" so those Welsh plugs are 0.0235 under the hole and that close tolerance indicates some form of machining the seats, so look for it while you're scraping. Squishing the dome stretches the outer rim to mate against the seat, but don't forget the #2 Permatex. It seals and sticks, but use a minimal amount, like not much more than a whisper. You want it to stick and seal but you want the mating bodies to absorb pressures and temps, not the Permatex. I'll probably get called on this by some Permatex freak so use what makes you feel good but as is said in boat building, too much caulk is a slow way to take a swim.

When you eventually install Welsh plugs keep in mind that there is an industry standard as to how and how much to dimple them, and while I don't have the figures at hand I can assure you that beating the dog-snot out of them with a 3 1\2# hammer on a short handle isn't the trick. When it's time for me to change all of mine out I'll check with the manufacturer and they'll tell me the best way to use their product.

-Randy

-Randy

[BobT-47P15]

Those plugs aren't so easy to get to with the engine in place.

This is a 1955 model motor. Should be the same as older models.

[Don Coatney]

Randy;

1.625 is 1-5/8" the size of the hole. The plugs measure 1.6265 and that is .0015" larger than the hole. So a little force is required to get them into the hole initially. Then a whack with a BFH expands them and seats them.

[randroid]

Don,

I stand corrected. I should never try to do math in my head after a nine-hour shift and two beers.

-Randy

[david lazarus]

I recently replaced these plugs on my '68 Cortina, been a few years since I did this job.

Earlier advice is good, clean the machined "seat" well, I also used a rag with solvent to remove oil residue, lightly coated with a sealant/cement of your choice.

Then....I found it important to get the plug well back into its "seat". I even tapped very gently around the edge until I could hear that it was hard up against the "seat". Then you need a couple of firm hits to deform it.

My tools of choice are two hammers, one a ball peen. The ball end of one hammer rests against the plug, and you hit the ball peen with the second hammer. Wear glasses. looking for the middle of the plug to deform inwards, the area of deformation I work towards is a little more than 1/2 the surface area of the plug to be deformed inwards.

[Don Jordan]

I went with the Dorman 568-010. They actually had a web site though it was for MGAs it was still interesting. Apparently "freeze plug" is a misnomer. They call them core plugs. Long story and I won't bore you. They do fit right in, however, without having to hit it with a hammer. I just couldn't get the swing with a hammer to do any good.

I'm disappointed about the temp gauge. I guess it's back to the bay.

Real quick question: the engine got so hot it pegged the gauge but it was running when I shut it off. Today I tried to start it and while it would turn over it just wasn't going to fire up. I took a chance and rolled it down the drive way and it started. How much damage could be done by overheating? Bearings? Pistons & rings? But it did start.

It maybe time to pull the engine.

Thanks for the help I'm really taken by the ease of the Dorman 568-010.

[Plymouthy Adams]

core plugs is correct as this is where the sand is removed in the casting process..however secondary to this is the "freeze" protection that causes this plug to be popped out in an unprotected engine and thus hopefully spare the block serious damage due to a split from frozen water...can you imagine the process it would take to clean sludge out of a block if these little device did not exist..

[De Soto Frank]

Don,

The inside fender aprons should be in two halves: upper & lower. If you pull the lower half, you should have enough access to the side of the block to set your freeze-plugs. Might need to pull the generator, or other offending "accessories".

As far as to whether or not you "cooked" your engine, after you get the core-plug issue resolved, go ahead and drive the car a bit, keeping an eye on oil & coolant level, and oil pressure, as well watching for consistent white smoke from the exhaust, that continues after the vehicle has warmed-up.

The usual "worst case" consequences of overheating a flat-head MoPar are:

- warping the cylinder head (causing compression leak and/or coolant leak).

- "soft-seize" - the pistons/rings expand to the point where they jam in the cylinder, causing the engine to lock-up until things cool-down. If this has happened, it usually is accompanied by piston rings that have broken.

Overheating the engine does not usually cook the "bottom end" (bearings).

Bearings usually are wiped-out from oil starvation (or ethylene-glycol coolant getting into the oil, where it attacks the bearing metal - this happened to my '60 Windsor V-8 before I got the car).

You can also run a compression test ( engine warm, spark-plugs removed, throttle tied-open); if you have done this previously, compare the numbers.

If you don't have previous compression numbers, if the compression readings fall into a 10-pound variance, that is regarded as "acceptible".

If compression is low on two adjacent cylinders, that suggests a leaking head -gasket: re-torque the head bolts with the engine warm and test compression again.

Ideal compression is between 120 and 130 lbs; anything above 100 is adequate. If below 100 lbs, but even, then your engine is "tired" but may be adequate for local driving.

The MoPar sixes have been known to tolerate a tremendous amount of abuse; your engine may be okay...

Check it out, drive it carefully, and see if you note any changes from its previous behavior.

Good luck !

De Soto Frank

[Plymouthy Adams]

I believe you will find only the passenger inner fender has a removable apron..you pretty much out of luck swinging a hammer on the drivers side..I am not sure if a freeze plug insertion tool would be any help due to the fact you must dimple, not just merely drive into place..these have adjustable swivel heads that lock into place with a capture nut...

[De Soto Frank]

Well, De Soto may have simplified the fender aprons after the war...

My '41 has two-piece aprons, left and right. In fact, I drove it around for nearly ten years with the lower halves removed... ( they're back on now...)

I haven't had the chance to work on a '46-'48 De Soto...yet !

Frank

[Plymouthy Adams]

that is odd for sure..I have two 41 D19's..Bz Cp and a Town Sedan..both sides are one piece...as the car was to have shared the basic body with the DeSoto and Chry...cowl to rear, I had always been aware of subtle changes in front metal....my 46 and up Plymouth and Dodges through 54 are one piece drivers with two piece passenger side. The 47 Town Sedan drivers panels is two pieces in appearances, but it is still one piece as it is factory welded...

[Don Jordan]

Put the plug in and fired it up... so far so good. The only casualty it seems is the temp gauge - it peaked and never came back.

This week end I'll make another effort at a short road trip.

[De Soto Frank]

Take it slown & easy and see what happens...

If you get ambitious, you may be able to pull the temp gauge and repair it.

I seem to remember removing one of the gauges from my '48 NYer with the cluster still in the dash...

So, which soft-plug was it that blew-out (relative to BobT's photo) ?

Frank McM

[De Soto Frank]

Tim,

I did have a D-24 for a while, but never really dug into to it...

The '41 De S / D / C cars were an all-new body, so things like the fender aprons may have been proto-typical, and received later refinements as the cars continued in production.

With my '41 De S, the lower and upper aprons are not fastened to one-another; there's a strip of welting attached to the meeting edge of the lower apron, and it's a "friction fit" against the lower edge of the upper apron.

I have noticed a dull "dribble" coming from the front end of my S-8 since putting the lower aprons back it; it may be the two aprons flapping against each other... a one-piece or welded shield would not do that...

Frank