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What are the chances that cooling system stop leak will clog my car?

I always carry a bottle of cooling system stop leak for emergency purposes only. I carry a bottle of “bar’s leaks liquid aluminum radiator stop leak” in my trunk. If I have to use it one day in an emergency situation then what would be the chances that it could clog my cooling system? That is what I am concerned most about. Is their any chance it will clog my system or is it a pretty safe product?

I’ve used it when camping in the woods of Maine when my Chevy developed a minor leak in the radiator. This was a metal unit, and it allowed us to travel home, a distance of 1000 miles or so and get it fixed properly.

I doubt if it will clog up your system when used as directed, but you should be prepared for a new radator whn you get back home, which would also entail a cooling system flush. The new plastic and aluminum rads are not repairable.

If you spring a small leak in one of the hoses, a roll of Duct Tape will do nicely. Just loosen the radator cap to reduce the pressure and you’ll be able to get home. Of course the best solutionis to replace a hose on the road, if possible, unless you have an exotic car.

Toay’s engines are a lot more finicky and have smaller cooling passages.

If it were -15? with a -60? wind-chill? I"d be dumpin’ that stuff in a heart-beat to get to a warm place.


From experience, get AAA and if your car overheats, call them and have the car towed. These products, temporary as they are, can shut down portions of your radiator, and can damage your head gaskets. The best thing to do if you notice that your car is overheating is pull over and shut it off right away, and get it fixed.

So, after you pour in the “stop leak” product, what will you use to replace the coolant that has leaked out?

And even if you have coolant, the “stop leak” doesn’t work instantly.

Unless you drive in a remote area, where there is no traffic and very low population density, I can’t see worrying this much about a leak.

Most coolant leaks are not catastrophic. A slow leak can be nursed along for a while, as long as you keep the cooling system full. If you have a catastrophic leak, like a blown hose, the “stop leak” won’t do you any good.

If you’re worried about cooling system leaks, I’d suggest carrying coolant rather than “stop leak.”

There was an episode of Mythbusters where they put a raw egg into the radiator to stop a leak. I thought for sure that was a myth but it worked. Car was running with water circulating. They cracked an egg into it and in just a few minutes it stopped leaking.

I have used the product on a number of occasions. I never experienced a clogged system.

Have you used this product on a number of occasions in the same vehicle, or in different vehicles?

If you use it once, you’re probably OK. More than once and it will begin to clog your radiator, heater core, and possibly even passages in the block if they’re small enough.

I would personally avoid it except in dire emergencies and/or in an old beater that you don’t care about too much. I definitely wouldn’t use it on anything that has any warranty left.

I used Bar’s Stop leak on my 2004 Dodge Dakota and it gummed up my radiator, Heater Core and hoses. Dealer is now taking me to cleaners for $547 to repair. If Bar Leak is honest and would like to pay this bill for me because it ACTULLY caused problem, I would be grateful. I can send the bill to provide proof that it does more damage that good. 2004 Dodge Dakota.

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I really don’t see why you want to send a copy of your bill to a forum . Bars Leak is not going to pay you anything because their product has plenty of warnings on the label . Besides they can say you did not use it properly or your system was beyond help.

It’s designed to stay a liquid until it comes in contact with Air. Then it will solidify.

I’ve used in every once in a while over the years as a stop-gap until I could get around fixing the leak.

I’ve used it for decades with success and no problems. However, it was the original type, not the aluminum.

In the olden days, I used the stuff, but changed to filling with fluid, loosening the radiator cap, using some hose repair tape if a hose, or crimping off the radiator hole if too severe, and turning on heat if needed and making a replacement repair, not sure how this works on today’s cars, but got me across the then vacant of gas stations and cities lands of Nebraska I think it was,

No, you actually caused the problem. You actually used the stuff, no one forced you to use it.

For small leaks a can of Stop Leak won’t cause any harm.

Once, while camping in the woods of Maine, My Chevy’s rad sprung a leak., I got a fellow camper to drive me to the nearest town where I picked up a car of the stuff and put it in, Topped off the rad with clean water. We were 700 miles fro home and on our way back. I drove carefully watching the temperature gage constantly.

After getting how without a mishap, I had the rad rebuilt; you could do that then, and lived happily ever after

The original post is from 2010.
The subject per-se may be still valid, but unless someone with a leak exhumes it, our responses are helping nobody.

A friend stopped a head gasket leak in a 302 engine and used a lot of sealer. The radiator plugged solid and he replaced it with a used one. Using it to stop a radiator leak won’t hurt a radiator that doesn’t have fins missing due to corrosion. The ones that can’t cool are dead anyway.

So I have an older Impreza known for head gasket failure. Added stop leak to it in April. 30 000 km later and 6 months, it just recently started to drip after turned off. I added more stop leak and I am hoping to get another 6 months. Your answer, 100% cooling system will be clogged. My solution, just keep driving it and keep expansion tank full. My slow drip hasn’t gotten worse.