As a reminder to those who are aware, and for those others just curious, here are links to my NeverEnding Story saga (still ongoing) that started out as replacing one rear wheel bearing but became new rear diff carrier & pinion bearings, new carrier bearing adjuster nuts, new (used) axle shaft, new wheel bearings & seals on both sides, new lug nuts, one new lug/wheel stud, a gouged out lug hole in wheel, and lots and lots of new toys tools:
Part 1 | Part 2 | Part 3

So as discussed in Part 3 of my NeverEnding Story, even though I was unsure of my rear diff gear contact pattern, I was under direct orders to move the truck out of the driveway before this weekend. So after finally getting everything back together, tires & wheels put on, and diff filled very late last night, then having to leave my new smart charger connected to the battery all night, early this morning I cranked her up. Immediately water starting pouring/streaming out of what seemed to be the back of the engine.

That's when it hit me: I royally screwed up....

She had been parked for months, and when we got a couple of days of way colder than normal hard freeze temps, since I wasn't and hadn't been driving the truck, I didn't even think about the fact that she had been leaking coolant prior to the rear axle work, and I'd been just topping off with water when needed until I got around to dealing with it - which I haven't yet. So my assumption was that the mostly-or-all water in the cooling system froze and busted & cracked something. My heart sank.

I drove her into the back yard and parked. When I went back to the driveway I thought it odd to find two perfectly round, tarnished, metal discs lying on the concrete near the puddles of water.

After perusing this forum, I discovered that those are "freeze plugs" or "expansion plugs" or "core plugs." I'd either never heard of them, or didn't know what they were when I heard/saw them mentioned, so it was in one ear and out the other.

Everything I found on the forum discussing these mysterious discs were about people replacing them because they were corroded and leaking through or around them. These two have some surface rust, but seem thick and solid.

I am assuming that during that really hard freeze, these plugs did their jobs and popped out when the water in the system froze and expanded. So maybe my stupidity did not mess up my truck as badly as I originally thought...???

My burning questions, assuming my hypothesis is correct, are as follows:
- What are the odds/chances that these worked perfectly and my engine wasn't damaged?
- Would it be OK to temporarily re-install these so that I can check for other leaks/damage?
- Other than obvious drips or water streams, what are some ways to check for or determine whether there is damage?
- On the repair roadmap was already a bunch of engine work including the plenum. If everything seems OK after installing the freeze plugs, when I do get around to doing that engine work, what should I look for regarding potential internal freeze damage?

Thanks for all insight, pointers, & help; and even any mocking, verbal bashing, & whoopins.

Signed,
Your forum igmo (a term we used in east Alabama as kids in the 70s & 80s, which you may have heard on Rick & Bubba),
Moonpie

 

Not beating on you but that's why I never fill with straight water in my cooling system or windshield washer reservoir. I know you've learned so, again, not rubbing it in.

Anyway, no idea if the freeze plugs can be reused. I'd probably get new ones. You can look for obvious cracks but HIGHLY unlikely you could make out additional damage with the human eye. I'd replace the plugs and see if she overheats, leaks elsewhere or you get a milkshake in the oil pan.

You could also replace the plugs then pressure test the system, but that might not prove a whole lot if you have a hairline crack somewhere....depending upon location and expansion/contraction with heat.

Basically, it'll run fine and be ok, or not.

 

You might want to look at the all(with the exception of the ones in the back of the block) of the other plugs to see if they are in place or started to come out.

 

Don't re-use the old ones. Get new, brass freeze plugs.

If the block is fairly clean, real possibility you will SEE the cracks, depending on just how bad it is.

 

Many lives ago a buddy had a CJ-5 with a 360 swapped into it. He did the same thing and popped a couple freeze plugs out. There again it was more of a Colo "spring" freeze. If it had been a January all-night cold soak, goodnight, forget it. No permanent damage this time for my buddy.

Then there's places like where poor @HeyYou is at...I think they have 10 months deep freeze and 2 months hot, humid summer

 

Well, it's not quite that bad. Climate change has been doing me some favors. Winters are fairly mild, and I haven't seen the WEEKS! of sub-zero temps for several years now. We don't get a lot of snow, to the point that I don't even bother mounting up my snowblower on the tractor.... It DOES get pretty friggin' hot in the summer though.... but, when the temp gets much above 86 or so, I just hide inside, and crank up the A/C.

Back when I was younger, I rebuilt a motor to drop into my dad's Caprice. It was summer when I built it, and I skipped putting in coolant, as I was a poor college student at the time. Told my dad to get a coolant flush, so it would actually HAVE some anti-freeze in it.... but, it ran good, drove nice, heater worked, so, he 'forgot'. Then it got COLD. I got a call one morning that the car cranked very slow, and made strange noises..... Later in the day, when it actually made it above freezing, I went over, had a look... saw all the water on the carport floor, and asked him if he ever had the coolant addressed. Nope. Crawled under the car, and the block was spider-webbed on both sides. It was trashed.

 

 

Well come on, it just got a hot water rinse......

 

Spider webs just stress-relieve the block to increase durability!

 

Moonpie: "so it was in one ear and out the other."

In forums, shouldn't it be "in one eye & out the other"?

Freeze plugs likely get too distorted to reuse them. ​​​​​​My 1st thought was a pressure test, as someone else mentioned. Alternatively, remove the oil pan & see what's there. Guessing from a pre-existing work plan, you're probably going to do that anyway, right?