Bar's Leaks 1109 Liquid Copper Block Seal, Intake and Radiator Stop Leak, 18 oz. | One Step, Safe for All Cooling Systems

OMG thank you for this wonderful product!! I used it in my old skid steer which was leaking a lot and overheating. Replacing the radiator does not seem to be an option- it’s above my ability and can’t find a mechanic to work on it. I had tried other radiator seal products with unsustainable results. As a last ditch effort I ordered this Bar’s copper block seal and it WORKS!!!! It has been several months and is still working, I am so very happy. The cost is a bit higher than the other products that did not work. For any future problems I won’t waste my money on cheaper products, this product is totally worth the extra few dollars. In the end it has literally saved me hundreds of dollars.

I had a minor coolant leak coming out the passenger rear side of my block, about several drops after engine shutdown, small head gasket leak. I added a bottle of this stuff and it seemed to have stop the leak...been several months so far. So far, so good. 1997 Ford F150 4.6 V8 with 140k miles. Engine has never been apart.

Purchased this as a ‘band-aid’ fix to get me to my repair destination. While I have relied on this leak sealant before more upwards of 8 months, it is recommended that you use this as an interim solution and resolve your larger issue as time and money allow. When using it, follow the instructions and ideally only use it AS NEEDED. Research suggests that overuse or reliance on products such as this can lead to larger problems.

Bar’s Leaks Liquid Copper Block Seal really delivers. The one‑step formula makes it simple to use—just pour it in and let it circulate. Within a short time, it sealed a small radiator leak and stopped coolant loss without any complicated process or extra tools. The 18 oz. size is generous enough for most vehicles, and the copper formula feels more heavy‑duty compared to standard stop leaks. It saved me from an expensive repair and kept the engine running smoothly. For anyone dealing with minor intake or radiator leaks, this product is a reliable, cost‑effective solution that works exactly as advertised.

Used as directed. Didn't work on first drive. Going to give it few days and see what happens.

Used on 2019 Chrysler Pacifica, crimp style radiator was leaking, the copper seal got the job done with only using 2/3's of total amount. Put in and road test for about 10 miles out and 10 miles back, check over. No leaks. Thanks

I had noticed water dripping from my truck but couldn’t ever find where. It was a slow drip and I’d add maybe a pint or so of antifreeze every week or so. So I decided to buy this and hasn’t leaked a drop.

I purchased Bar's Leaks 1109 Liquid Copper Block Seal hoping for a straightforward fix to my coolant leak. Given the "Amazon's Choice" badge and 4.3-star rating, I expected at least some improvement. Instead, I got a wasted afternoon and what sounds like a bigger problem. What I Did: I followed the directions precisely – used only half the bottle as recommended, flushed the system with clean water first, and made sure the engine was running clear before adding the product. I didn't cut corners. I wanted this to work. The Result: Zero improvement on the leak. Coolant still disappearing at the same rate. But here's the kicker – after adding this stuff, my engine started making a worse noise than before. I don't know if it's related to the product or just bad timing, but the correlation is hard to ignore. Now I'm out the cost of this bottle plus facing what sounds like a more expensive repair. Bottom Line: This was a gamble that didn't pay off. "Pour & Go" turned into "Pour & Pray & Still Leaking & Now What's That Noise?" Save your money and skip straight to proper diagnosis and repair. I can't recommend this product based on my experience.

No more minor leaks . Water pump no more noise.

Did what it said and stopped a block leak in a 2007 Mazda 3. I only needed to use half the container, so I still have some left for another leak down the line. Not much else to say.

Bars a is always a good product . Just used as stock this round.

I was told my head gasket was going,after using Bar's it took only 2 bottles over a 2 month period and since then no more head gasket issues ,like over heating,my van runs good now.

Had a small leak around the joint on radiator and this unfortunately didn't do the trick. Neither did anything else we tried. I guess it depends where the leak is. It did however make everything glittery.