oops - small hole in radiator - How to Fix ?

DougVieyra

DougVieyra

Well-known member
Screw driver accidentally slipped and made a small hole on the bottom left side of radiator on my '31 Coupe.

It has been awhile (60 years) since I last worked to stop a leaky radiator. The remedy back then (low tech from the '30's & '40's) ranged from egg whites dropped in (which was supposed to solidify as it found the leak) the radiator's hot water. Then there was the 'Old Faithful' - chewing tobacco, which folk lore said had the same effect of stopping the leak. A couple of other 'tried and true' shade-tree folk remedies also filled the non-mechanic tool chest.

However, now, I suspect that there may be more sophisticated 'miracle' ointments that can stop a leaky (small hole) radiator. Short of doing anything ridiculous, like taking the radiator out of the car and taking it to a proper radiator repair shop, what do you Ford Barn sophisticates do to solve this problem ?
 
I would remove the radiator, scrape the area clean with an Exacto knife, then solder it with good 60/40 electrical solder and flux.

I'm wondering what you were doing with a screwdriver facing the radiator? I can't think of any screws that close to the fins and tubes.
 
I agree with soldiering the hole. Drain it, dry it, clean it to the metal like Tom said and soldier it. This way you don't introduce some foreign substance to your entire cooling system and engine when all you have is a small hole. If you dont want to tackle the job a radiator shop will do the job easy. There are also various types of Stop Leak to just pour into the radiator that you can get at any auto parts store.
 
What is a 'Small hole', how pointy was this screw driver, how hard did you hit the radiator and is the bottom left on the lower tank?

To put a hole in the lower tank with a screwdriver would take a healthy impact on a tank in good condition. Make sure the impact did not just open up a pinhole already formed but not completely through the metal as there are likely hundreds of additional pinholes waiting to leak.

If the leak is a 'weeper' hole then additives might seal it. (Personally I hate the idea of putting anything that 'plugs' into my radiator.)

Soldering is the most proper, short of removal and repair, but can also create more leaks during cleaning and getting enough heat into the lower left corner may be a problem.

Will the small hole take a small screw?

A small screw with some form-a-gasket #1 or 2 on it, screwed into the hole and gentle snugged might be an eaiser, more permanent, temporary fix.
 
Last year on a country drive, the inside "L" neck on my pressurized '28 Phaeton's radiator began leaking. After a while, I could wiggle the neck and see where it was separating from the upper tank. Nursing it home and not trusting the bozo radiator shops in area again, I checked around and was told to try patching the crack with Quik Steel. It's supposed to stay intact up to 500 degrees, way more than a Model A will ever generate. JB Weld cannot withstand the kind of heat created by the Model A's coolant. This I have learned in the past. Quik Steel is a putty substance that must be kneaded in your hands for a minute or so until it starts feeling warm. Then apply it over the crack or leak, preferable after the area has been dried. It sets up in less than 15 minutes and cures in an hour. I applied the stuff and even though the water gets very hot in the upper tank, it has held that neck in place for a year and shows no signs of leaking.
You might try a little of this stuff on the radiator hole, possibly first cover the hole with a small piece of paper so that the Quik Steel doesn't ooze inside the tube/lower tank and plug it. If this doesn't work, you're only out a couple dollars, but you may also save yourself a ton of work and expense at the local rip-off radiator shop. (No, my experiences with radiator shops have not generally been good. Could you guess?)
Marshall
 
if you want a simi pemenate fix use sodium silicate, called water glass, its sold at most parts dealers, it was used, and I used it to repair cracked blocks in the ford v/8, that stuff works, will seal a crack that you can put the edge of a knife in, it works on contact with heat and air. it will plug any thing exposed to those two things, so if you do use it, FOLLOW THE DIRECTIONS PRINTED ON THE CONTAINER, it will take about 15 or 20 minutes of engine running to get it to operating temp, then another 15 or 20 minutes for the stuff to stop the leak, you will need to drain and flush the rad and engine, fill completely with straight water, and run how ever long it takes to stop the leak, then drain and flush the engine real good, as I said earlier this stuff really works
 
Find a sheetmetal screw slightly larger than the whole and get a fiber washer and coat the screw and the washer with permatex gasket maker. screw it in and it may last till you take your radiator off to resolder it.. I have used tis method before and it was a permanent fix..
 
ford3 said:
if you want a simi pemenate fix use sodium silicate, called water glass, its sold at most parts dealers, it was used, and I used it to repair cracked blocks in the ford v/8, that stuff works, will seal a crack that you can put the edge of a knife in, it works on contact with heat and air. it will plug any thing exposed to those two things, so if you do use it, FOLLOW THE DIRECTIONS PRINTED ON THE CONTAINER, it will take about 15 or 20 minutes of engine running to get it to operating temp, then another 15 or 20 minutes for the stuff to stop the leak, you will need to drain and flush the rad and engine, fill completely with straight water, and run how ever long it takes to stop the leak, then drain and flush the engine real good, as I said earlier this stuff really works
Click to expand...

I have heard this water glass does work well. Although it is not recommended if you are running a leakless seal waterpump. It was a written warning with the instructions of my waterpump with the l eakless seal.
 
Tom
Why would you use electrical solder which is usually rosin core instead of acid core solder for metals or lead bar with acid and flux? Just wondering. Does the rosin core work better?
 
JOES31 said:
Tom
Why would you use electrical solder which is usually rosin core instead of acid core solder for metals or lead bar with acid and flux? Just wondering. Does the rosin core work better?
Click to expand...

Yes, I've always had much better luck using rosin core solder than the acid core solder. If it's just a small hole and easy to reach, I'd scrape it clean by using a sharp Exacto knife, then solder the hole shut. This way you will have a permanent fix.
 
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Tom Wesenberg said:
Yes, I've always had much better luck using rosin core solder than the acid core solder. If it's just a small hole and easy to reach, I'd scrape it clean by using a sharp Exacto knife, then solder the hole shut. This way you will have a permanent fix.
Click to expand...
Thats what I would do as well, using a large soldering IRON. An iron is easier for me to control than a torch. If you can get at it, a polishing tip on a dremel tool works good for cleaning the area, has to be super clean to do a good soldering job.
 
Soldering with acid flux will be easier and perhaps more successful for a novice, however it can cause more corrosion in the future than rosin flux. Personally, based on much experience with soldering, I would use acid flux to repair a radiator and make sure the area was adequately cleaned afterwards.

I only use rosin flux for soldering wiring and other situations where corrosion from acid flux cannot be tolerated.
 
I wouldn't recommend it, but the guy next door to me that owns a body shop had a mustang that had a rotting radiator in it. Every time it sprung a leak he put bondo
over the hole. Over the course of a year or so he must have had 15 or 20 patches on it.
It never leaked from the same place twice, he put it on when the radiator was hot and
never even drained the water out of it when he did it..................
 
Thanks to all who took the time to help me with a method of plugging the leak in my radiator.

The tiny hole has been repaired and the leak has stopped. Leaving the radiator in the car, I proceeded to take Tom Wesenberg's advice:

" If it's just a small hole and easy to reach, I'd scrape the area clean with an Exacto knife, then solder it with good 60/40 electrical solder and flux. I recommend using rosin core solder rather than the acid core solder. Then solder the hole shut. This way you will have a permanent fix."

If anyone has one of these '30-'31 Radiator Shrouds hanging on his wall, I would strongly recommend that you LEAVE IT on the wall ! It is just not worth the trouble to install - unless you have not yet put your car together, and REALLY do have a serious NEED of it.
 
My dad told me that years ago he would put some black pepper into a radiator that had a small leak and it would "patch" the leak from the inside. Now how much pepper?; would it settle elsewhere?; etc. I don't know. I'm just bringing it up here as a method to stop a small leak. Perhaps it could be a lifesaver when on a road trip and you need to get home.

Has anyone ever used that method or even heard of it?
 
Yes, I have a friend that I trust about anything mechanical, who recommended the pepper idea for a cracked head once. He swears it works, but not with antifreeze. Drain the system, add plain water, add a small can black pepper with engine running and taadaa, no leak. He told me an old timer showed him that year's ago for a leaking block he had in a truck. Said he ran the truck for 3 years after the pepper fix with no problems. Good e-fix for out on the road. Happy driving!
 
I'm curious when it comes to soldering a radiator why you wouldn't use silver solder? When I replaced the neck on my mine I used silver solder because that's what I was told to use...is the 60/40 is easier to work with or have any better properties? Correct me if I'm wrong but doesn't silver solder have a higher melting point?
 
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