Any problem with adding Bars Leaks to fix a very slight seep ?
Of all the stop leaks I consider Bar Leak the worst of the bunch. It WILL settle in a big glob in the bottom of the outlet and plug any transfer of water to the block. If you are going to try and stop a leak go the drug store and get a quart of Sodium Silicate. If they don't have it in stock they can order it in. The last drug store I got it from was Walgreens. Most all the stop leak that you get in a parts store is mostly Sodium Silicate, if you look on the containers.
If it were me I'd add it and run that sucker all day till it sealed then yank the lower radiator hose off and flush it out with a hose.
Also remove the little drain petcock and clean it with carb cleaner to ensure there is no residue to plug it up.
You know....if you have a drilled radiator cap you maybe could presurize the system ever so slightly. Plug off the overflow tube with a rubber cap or something then get some fittings to allow you to put an air chuck on the top. Maybe put 5 or 10psi on it while it's running and hot?
Hmm...I might try this on mine to seal a little leak
Ralph, if you can get to it, I would clean it up good and smear a dab of RTV sealer on it from the outside. I hate to put anything inside for a sealer, that just puts another layer of crud on the inside of the tubes, making it even harder for them to transfer heat. JMHO. Dave
IH makes a good one and pre mix i think is better than just dumping it in? I also would NOT put any air pressure on a old round tube rad?? Bud.
I used Bars Leak in my previous radiator, and it deposited a thick slime coating to the entire inside of the radiator. It was a thick enough coating that it no longer cooled adequately. I flushed it out and used a radiator cleaner to clean out the coating and then used Alumaseal with much better results.
Bars Leak is what my Dad had put in our 27 coupe. After he died, it sat for 25 years without being started. Thank God, I didn't try to start it. When I pulled the water pump off the block, the pump was locked up, as my Dad used to say, "tighter than Dick Tracy's hatband". Not from rust, but from a solid mass that resembled soggy oatmeal that also completely plugged the block where water is supposed to enter. I dug out as much as I could with my finger, but will have to backflush the block until all flows well. The car is getting a new radiator, but the pump is getting tossed.
Bars leak is bad for hoses they will absorb it and become soft spongy felling oily. Duane
Bar's Leaks is just a brand name. The company makes several radiator leak sealer type products. Which one is the one that should never be used?
For sodium silicate or water glass to really work like it should, the system must be pressurized.
Mike, I once stuffed a rubber plug into the upper end of the overflow tube to try to get some sort of stop leak to work better. I don't recall what product I was using, but the plug did pressurize the system.
My actual experience with Sodium Silicate:
I've used it satisfactorily to stop, or really slow down some leaks in about half a dozen Model T radiators over the last five years or so. You DO NOT have to pressurize the radiator to make it work, and you do not need to use much. It will actually work better if it is allowed to do its job slowly and the system is not pressurized. A little goes a long way. I get the vehicle up to operating temperature (at least half way up to where the moto-meter registers "summer average"). The engine has to be up to operating temperature and the coolant has to be naturally circulating for this to work properly. With the engine idling, measure out 3 ounces of Sodium Silicate and pour into the radiator in a thin stream (slowly). Put your radiator cap back on and drive at least half an hour, or longer if possible. The leak may stop right away or it may take a few more heating / cooling cycles. Sodium Silicate will stay in solution with water and/or coolant and then turns to a solid when exposed to the carbon dioxide in the air. Basically what will be sealing your leak will look like a white mineral deposit. If your leak does not seal by using this method, your radiator needs to be properly repaired or replaced. A quick fix like this is nice, but there is still no substitute for a proper repair. This repair may last the season, or a couple years, but any way you slice it, if you are using any kind of stop leak product, it is a good idea to start saving $20 to $40 per month for a new radiator or a qualified repair job.
It is not a good idea to keep dumping more in if your leak is not sealed. If three ounces don't show any results, then it is very likely NOTHING will work.
I've never been able to find Sodium Silicate in any of the conventional places people claim it is available. Here is where I get it for $8 per qt: http://www.enasco.com/product/SB10453M
If you have a home foundry setup and do any metal casting, you can also mix sodium silicate with silica sand to make a nice air-set foundry sand for making small castings and cores.
To answer your question, the one I used (and didn't like) was Part Number: PLT11. The one they call Heavy Duty, which has pellets in a thick liquid. It did stop the leak, by the way, until I flushed it out with radiator cleaner to get out the slime.
A Sodium Silicate question for those experienced with it: Can it be used with antifreeze in the system, or must it be plain water?
Sodium silicate did not seal a friend's Model A block which had a small crack in the water jscket. I know it was for use in steam boilers under pressure. That's why I said it works "best" under pressure which forces it through the leak.
We got it at the Wal-Mart pharmacy. It came in a Mason jar.