Leaking Freeze Plug

[Bingster]

Just as I am about to do a first start on my '47 DeSoto, I noticed a small leak coming the freeze plug near the oil filler pipe. It's not green liquid. I have no anti-freeze in the radiator. I don't know why there's water in there. Car's been sitting for ten years. Attempting to start the car a couple of weeks ago must have brought out the weak spots. Engine turned okay but didn't fire. Found out the new battery I bought was bad. Coil was bad. Points weren't set right.

 

Now it should fire.  But I wouldn't think a leaking freeze plug would hurt anything? Must be a lot of crap in them, though.

[D35 Torpedo]

Sounds like an omen of things to come. A leaking frost plug tells me the block is full of crap. Overheating will ensue.

[soth122003]

Leaking freeze plug shouldn't hurt the starting of the car. Once your up and running, I would do a flush with vinegear and rinse with water. See other topics on flushing the cooling system (let the flush solution set in there a few days or miles before rinsing). The with that done address the leaks. Also when you replace the freeze plugs, clean and flush the gunk out before installing the new ones. 50 psi water hose and sprayer worked wonders for me by spraying in the freeze plug area.

 

Joe Lee

[Bingster]

Our house is up for sale and this start-up is the last thing I'll do for awhile. Yeah, I guess it would take a lot of crap inside to rust out a freeze plug.  And while it intrigues me to tear down an engine and rebuild it, when added to the entire project it's a lot. I'm 70 - a healthy and fit 70 - but I also have other things to do professionally. My thought was that even if I sell the car it's better to say that it runs.

 

But it does give me a great calming effect working on the old car, and it's a nice change from "life".

[Los_Control]

There are threads here covering this common issue. Just very common for this area of the block collects crud and leftover casting sand .... you can confirm this by opening the drain petcock located near the oil fill pipe ..... It plugs up the drain hole and you can not drain the water out of the block.

 

Knowing you will basically be putting the car in storage for some time .... I would be concerned to get the water out ... wondering why the block has not already froze & cracked .... maybe it is not much?  I would suggest adding antifreeze to it, if the plug is leaking thats no good.

 

I would want to add water to it when you start it, just to let it warm up and give you a better idea about condition of the engine.

If the petcock does not drain, you can always remove it from the block then use some stiff wire to snake out some of the crud and get it to drain.

[SteveR]

3 hours ago, soth122003 said:

50 psi water hose and sprayer worked wonders for me by spraying in the freeze plug area.

 

I have used vinegar for flushing out the cooling system. I think I used about a quart of the stuff. I was amazed at how much gunk came out. I then pressure flushed with water and AN air compressor using a nozzle https://www.amazon.co.uk/Flushing-Coolant-Powered-Cooling-Cleaning/dp/B0B523D565/ref=asc_df_B0B523D565/?tag=googshopuk-21&linkCode=df0&hvadid=606772809965&hvpos=&hvnetw=g&hvrand=8506938398015583691&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007256&hvtargid=pla-1795408044477&psc=1

I also have 1 weeping frost plug and will be replacing this.

[andyd]

When or if you replace the freeze plugs use brass plugs, they never rust & will outlast the car.

[Bingster]

I think there are still some "warm" days left in October here, and I am inclined to drain the engine with that petcock (I hope it doesn't break off) and at least replace the bad freeze plug.  I would like to take them all out and flush the system, but if I  get caught not replacing all of the plugs and it turns too cold, I can't fill the radiator with anti-freeze for the winter.

 

I am hoping to find a house with an attached garage where there is heat. Right now the car has been under cover but no heat.  There is only a trickle coming out of the freeze plug.  I'm hoping that I don't screw up the middle rusted out section of the plug and have to deal with removing the rim.

[Dan Hiebert]

That one particular plug you're referencing is more prone to corrosion that the others, there is a different gap between the cylinder walls there, that leads to more crud getting in and accumulating against it - it also happens to be the "easiest" one to replace.  I had to replace that one in our D24 about 10 years ago.  I echo previous comments, it won't hurt getting the car running.  You should fix it as soon as you can, though.  Once they start seeping, they only get worse, especially if the car is sitting. 

Edited October 13, 2023 by Dan Hiebert
Typo

[Sniper]

1 hour ago, Dan Hiebert said:

Once they start seeping, they only get worse, especially if the car is sitting. 

 

My philosophy, after playing the replace only the leaky one game, is that once one starts leaking the rest aren't far behind.  So I replace them all, yes a PITB, but that's how I am. 

[Booger]

if Im not mistaken theres a freeze plug on back of block by firewall. Thank you Wm Chrysler

[Booger]

modern coolants have lubricants and are not just "anti freesze". plain water just doesnt make sense any more

[Sniper]

2 minutes ago, Booger said:

if I'm not mistaken there's a freeze plug on back of block by firewall. Thank you Wm Chrysler

Yes, I told you it was a PITB.  But I'd rather replace it at the time of my choosing, in my garage rather than having it let go on the side of the road somewhere.

[Bingster]

Thanks all!  Can I remove the oil filler tube without any oil going all over?

[soth122003]

1 hour ago, Bingster said:

Thanks all!  Can I remove the oil filler tube without any oil going all over?

Yes, but you need to cover the hole to keep water and crud out.

 

Joe Lee

[Bingster]

SteveR . . . You just pour a quart of white vinegar into the system and let it sit and flush it out with that tool? Does the tool really work? At least once?  Is a quart enough to do the trick?

[Los_Control]

I have gone by what others have done in the past .... I bought I think it was 6 gallons of vinegar from the grocery store .... I filled the cooling system with 2 gallons and maybe topped it off with water if needed.

 

Then I ran the truck through several heat cycles over a period of 2 or 3 weeks ..... while sitting in the driveway ... not roadworthy at that time or yet.

Then I drained it and repeated the process again.  .... continued it over several months.

I also pulled all the soft plugs, dug out a ton of sand and flushed the block good before adding the vinegar soak treatment.

 

My truck I believed was parked because of overheating issues. Today it can idle all day in the driveway in 100 degree Texas heat .... creeps up to about 185 then the T-stat opens up, cools it right down to 175 or so then eventually creeps up to 185 again ... T-stat opens .... rinse & repeat.

 

 

Others with driving cars have filled the cooling system with straight vinegar then take them on a nice long drive. They repeat this a few times then flush and add regular coolant.

 

A quart may be all you need, straight vinegar will not hurt either.

[soth122003]

I had flushed my system with 2 gallons of vinegar when I first got it years ago. Ran great and at about 170 degrees. I had a leaking freeze plug last year. When I pulled the plug, water wouldn't even drain from there until I cleaned it out. I flushed the area fwd and back from the plug with a water hose with the pistol thing to give me a high pressure stream and lots of gunk and sand came out. The original flush did not have the pressure to remove the packed sand and crud that the water hose had. After replacing the plug, I did another flush 2 gallons vinegar and 1 gallon water for about 2 days maybe 20 miles and a lot of brown fluid came out but the temp still ran the same at about 165-170 degrees. 

 

Joe Lee

[SteveR]

12 hours ago, Bingster said:

You just pour a quart of white vinegar into the system and let it sit and flush it out with that tool? Does the tool really work? At least once?  Is a quart enough to do the trick?

I drove the car around for about a week. I made sure I looked at the radiator filler to see if it was working. I could not believe the rusty foam that came from it. I then flushed it out with that gun. Before I had overheating problems after I did not.

I do not think in my case it was a fix. It was a bandaid at best and I was able to run this season with no problems. I have noticed this week, I am getting some rust in the coolant, and it's time to do a better job.  BTW you will get wet doing this.

 

You do not want to drain the radiator with all that crud floating on top. So I blasted it out of the filler. I used the heater hose to the engine which goes through the distribution tube and up to the top of the radiator. I then changed to different points to do a cross flush.

 

 

[SteveR]

11 hours ago, Los_Control said:

A quart may be all you need, straight vinegar will not hurt either.

I do not remember how much I put in. Mine was a guestimate. Ya, I would fill the radiator next time with white vinegar.

[keithb7]

These rear plugs....As discussed above. PITB.