Block Seal Coolant Leak Fix Stop Leak (1109)

Liquid Copper


  46 Reviews

What does it do? Our formula permanently repairs larger leaks in radiators, intake manifolds and gaskets, heater cores, blocks, heads and freeze plugs. It contains an antifreeze-compatible sodium silicate liquid glass formula, so no draining of the cooling system is required. Not to mention, it will not harm the cooling system when used properly. The intake gasket seal you’ve been looking for is far more effective, easy to use, and less expensive than you’ve ever imagined. This is why Bar’s Leaks exists: to offer usable, low-cost intake gasket seal and other products to auto owners who have no special experience or expertise. We’ve been doing this for over 70 years, so we know a thing or two about chemical repairs.


  1. Allow engine to cool. Make sure engine is cool enough so radiator cap can be safely removed.
  2. Shake well. Pour Bar’s Leaks Liquid Copper directly into radiator. If using in a small cooling system including all 3 and 4 cylinder engines, use 1/2 bottle. TIP: If direct access to radiator is not available and if overflow tank is pressurized, you can install in tank.
  3. Fill radiator and overflow tank to proper level and reinstall radiator cap. Start engine.
  4. Turn heater on hot and fan on high.
  5. Idle engine for 15 minutes.
  6. Turn vehicle off and allow engine to cool.
  7. Top off (fill up) radiator and leave Bar’s Leaks Liquid Copper in cooling system for continued protection. Drive vehicle as normal. For severe leaks, like a blown head gasket, it is recommended to use Bar’s Leaks Head Gasket Fix or professional-grade HEAD SEAL™ Blown Head Gasket Repair.

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You’ll find plenty of options when searching for products to fix an intake gasket leak. While our competition may claim to stop the leak quickly, their products don’t always perform as advertised and they sometimes make things worse. Their stop leak products can’t get your car back on the road like Bar’s Leaks — that’s why we’ve been the most trusted stop leak brand since 1947. Throughout our long history of serving car owners like you, we’ve used a team of dedicated chemical engineers to constantly develop and refine products that are safe, fast and effective in stopping intake gasket leaks and other automotive problems — including liquid copper and much more. Make sure to watch Bobby and Caitlin in our handy how-to video so you can become a “three-minute mechanic” and finally take control of that leak.


When you’re experiencing mild to moderate leaks, including intake gasket leaks and leaks related to power steering, engine oil, cooling systems, transmission and other key systems, in your car’s operation, Bar’s Leaks has the power to stop those leaks quickly, effectively and affordably. As the best-known stop leak brand in America, we have a long history of creating products that even the novice auto owners can use to extend the lifespans of their vehicles and, best of all, save money by avoiding costly repairs. Our products are made in America, just an hour outside of Detroit. And we can look back at nearly 70 years of service and point to millions of customers who have used our products to their satisfaction. At Bar’s Leaks, you’ll find intake gasket seal in the form of liquid copper, plus other effective products, that fit perfectly into your lifestyle and budget.

Find where to get your Liquid Copper today.

Customer Reviews

  46 Reviews
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 46 reviews
 by Nicole H.
It works

Been using it since forever, never let me down.

 by Ed B.
Fantastic product

Fantastic product, delayed the need for head gasket replacement over 2 years with a single use.

 by Bob S.
No more leaks and back on the road!

I want to give you folks a compliment, I own a 1957 Packard Clipper that is a survivor, never being restored. The radiator (never been serviced or replaced) developed a top tank leak. I stopped by my local auto parts store and told them what was going on and they recommended Bar's Leak Liquid Copper.

Let me tell you that this stuff is AWESOME!!!! No leaks and back on the road!

 by Peter C.
Kept my diesel generator running after hurricane damage

We were hit by Hurricane Ida on August 29th, 2021. We spent 14 hours in hurricane force winds. The wind blew debris, which made many pinholes in the radiator of my diesel generator. I spent 3 days babying my generator, checking it every 2 hours, day and night, and adding water to keep it from overheating. O'Reilly's auto parts finally opened up around the 1st of September. I bought your Liquid Copper permanent cooling system block seal. Without reading the directions, I added way too much of your product. It almost plugged up my radiator. I took it out and flushed the radiator. I then added the correct amount of the Liquid Copper and filled the system up with coolant. It worked great. My radiators leaks went to almost nothing. I could sleep through the night without having to check the generator every 2 hours. We spent 20 days running on generator. We finally got line power back on September 17th. Without your product a bad situation would have been much worse and I would have gotten a lot less sleep. Thank you for a great product.

 by Clifford A.
A product that does what it says it will do

Just wanted to let you know that I recently purchased and used your block seal liquid copper product on my 2005 Ranger and the head was leaking pretty good. I followed the two part instructions and it completely sealed the head leak. I appreciate a product that actually does what manufacturer said it would do, thanks.

 by Harold S.
Definitely worked for me

I have a 2007 Crown Victoria P71. Intake manifold starting leaking in two locations. Cost to repair would have been around $600.00. Bought a bottle of Liquid Copper back in November. It has been about 4 months. So far so good. I did not expect these results. May not solve everyone's problem, but definitely worked for me.

 by Mark P.
Just follow the directions and let the product work

I have used Liquid Copper Seal (1109) successfully in several autos that had blown head gaskets. My experience has been that if the gasket leak is not too severe this will usually solve the problem. It is surely an affordable alternative worth trying. Just follow the directions and let the product work.

 by Paul F.
Quite effective

I have used Bar’s Leaks Radiator Stop Leaks on three occasions, and I have recommended Bar’s Leaks Radiator Stop Leak with the liquid copper crystals to numerous customers shopping at Advance Auto Parts, Store #7041, 2543 west 12th Street, Store #5323, 6000 Peach Street, Erie and the Harborcreek store, the Edinboro Store in Washington Township, and the Girard Store, in Girard, PA over the last eight years. I advised the customers there is a warranty, to keep the receipt, and I have never had any complaints about the use or sale of Bar’s Leaks Radiator Liquid Copper. I have also recommended the engine block and head gasket treatment from Bar’s Leaks to several customers and have used this product myself on a 2006 Nissan Frontier V6 engine with good results.    

I never had to do any remaining repairs after the use of these products. Simply follow the directions and they were quite effective.

 by Dan L.
Worked like it claimed it would

Bar’s Leaks helped with a problem I expected to have to pull the engine to repair. I had a freeze plug that did not seal correctly on a fresh rebuild on the back of the engine where the trans bolts up. It was weeping, not really leaking. Constant coolant smell when hot. I tried Bar's Leak's Liquid Copper Block Seal but really didn't expect much. I was amazed that it took care of the problem without any drama. Worked like it claimed it would. It hasn't leaked a drop in a few years now. I am usually very skeptical but based on this product's experience I would definitely try another Bar's Leaks product if needed.

 by Randy R.
Fixed friend's Impala

Hello, I used the Block Seal product. It was on a friend's Impala that had a leak that was annoying him. I suggested your product that I have used in the past. Poured it in and he hasn't had an issue since. Great products!

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