Blowing a head gasket is one of those things that you can’t understand the trouble of until it happens to you. Sometimes there are warning signs, but often it just happens seemingly out of nowhere. That was what happened to us, driving in our second hand Ford to a festival in 2011, when all of a sudden a huge cloud of black smoke appeared over the car. Unfortunately, we didn’t have a head gasket sealer back then. But now we’re more careful and make sure to always carry one. These are our top five head gasket sealers.
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Top 5 Best Head Gasket Sealer Reviews
1. Bar’s Leaks 1111 Head Gasket Fix 24oz
This head gasket sealer is a fast acting solution which will lock up any leaks in no time. It is a mix of sodium silicate and various particles that when exposed to air will harden and completely seal any small rupture. It’s not the cheapest one available, but it comes in a large bottle and is highly effective for small bursts. That said, it is not advisable for bigger ruptures. The idea is that it will seal small gaps and long cracks. If you have a bigger rupture, you may need another solution, or to get a full repair. Also, if your engine is complex or delicate, do not use this sealer. Its particles may mean it sticks where it shouldn’t, resulting in internal damage. Great for your jeep or family car, not good for vintage vehicles or supercars. When using it, be sure to follow instructions closely to make sure it works well.
Our Rating: 
(3.9 / 5)
2. Permatex 80062 High Tack Gasket Sealant 4oz.
If you don’t want to spend a lot of money on a head gasket sealer, but you still want peace of mind, this may be a solution for you. This sealer is very tacky and will seal most cracks and gaps, including some larger gaps that bigger brands cannot handle. It comes in a smaller amount than many other sealers, in 4, 9, and 16oz containers, which means you can just keep a small jar in your car’s emergency box. And even at that size, it’s still great value for money. Plus, if you’re not feeling confident about your ability to apply it and you want minimal wastage, it comes in aerosol cans. This makes it much easier to use. It is also a great option when you just want to hold a gasket together until it gets to the repair shop, as it dissolves easily with spirit-based solutions. This sealer is the most foolproof one on the market.
Our Rating: 
(4.5 / 5)
3. Bar’s Leaks HG-1 Head Seal Blown Head Gasket Repair 33.8oz.
If you want a highly versatile sealer, then this is one of the best on the market. This is again more expensive as a single purchase. But not only is it very economical for a Bar’s Leaks product, it’s also useful for more than a blown head gasket! You can use it for all sorts of cracks and leaks in your car, from oil, to windscreen wiper fluids, to dripping brakes. You don’t need to flush before using it, and it’s antifreeze compatible too. Choosing this option really covers all bases. Bar’s Leaks reports it as their strongest product, and it really lives up to the title. Because of its unique mix, don’t try and mix it with anything before applying, and don’t use it on an area you have already treated with another sealer.
Our Rating: 
(3.7 / 5)
4. Steel Seal Blown Head Gasket Fix Repair Sealer 16oz
This is the most expensive one on our list, but it’s included for good reason. Many head gasket sealers dry and seal very quickly. This is great when you have a simple 4 cylinder engine. But when you have a 6 or 8 cylinder engine, the extra folds and extra complexity get in the way. They could mean your sealer hardens before it gets very far, or doesn’t coat thoroughly. Steel Seal has a few specific ranges of head gasket sealers for different cylinder engines. They have been tested and found to make sure the sealer reaches deep inside your head gaskets, sealing cracks and problems even at the furthest cylinder. This is especially important as Steel Seal advertises itself as a permanent fix. And trust me when I say, Steel Seal 4 cylinder will not permanently fix a head gasket crack in an 8 cylinder engine.
Our Rating: (3.7 / 5)
5. Blue Devil Head Gasket Sealer 32oz
If you need a large container but you’re on a budget, this is a good choice. It’s our favourite economical head gasket sealer, as it acts fast and seals strongly, even in more complex engines. It’s also free of any particles, making it gentle for even older or more delicate engines. And it’s another one that is advertised as a permanent fix, which is a little misleading. Although it can permanently fix smaller cracks and gaps, for the average-sized head gasket burst it will just glue everything together a short while. But it’s a good, fast solution that will help keep your car running long enough to get it home, get together the money for more complicated repairs, and sort your paperwork.
Our Rating: (3.7 / 5)
What is a Head Gasket Sealer
Many people purchase a head gasket sealer under the mistaken impression that it will totally and completely fix a worn-out head gasket. This is false for two reasons. Firstly, many head gasket sealers are not made to last that long! They can last quite a long time for cracks and minor leaks, for sure. But many will not last more than a week for big cracks, if they cover them at all.
The second reason it’s false is that your head gasket blew for a reason. There is something wrong internally with your car which created too much pressure, or which wore down the head gasket to a point where it couldn’t stand normal pressure. You can patch the head gasket, but if you don’t fix the root of your problem, the seal might break, or another head gasket might burst.
A head gasket sealer is largely a temporary patch until you can get a proper repair done. Or it may permanently fix that one crack, but you will still need to have your car checked to diagnose the root of the problem. When you blow a head gasket, whatever you do, you will always need your car checking over!
How to Prevent Blowing A Head Gasket
We found ourselves standing next to our car in a service station parking lot. The repair team had arrived and said the head gasket had blown. As we waited for a tow truck so we could get the car to a repair shop, where we could collect a hire car, we wondered what we could have done to prevent this. There is never a good time to blow your head gasket, but our situation really drove it home how difficult it can be. We had to wait for a tow truck, go almost all the way home, then move all our stuff into a hire car. We barely made it to the festival by sundown. Then there were all the costs. Towing, repairs… at least the hire car was complementary. And we were determined never to have that happen again. This is especially important as, as we have discussed, sometimes a head gasket can’t be fixed with sealant alone. To avoid blowing a head gasket:
- Bear in mind all head gasket bursts are caused by overheating. Normally your car can cool itself, but in certain circumstances it may have difficulty doing so. This is usually due to age or damage.
- Use the right coolant. All manufacturers specify which coolant to use. Using the wrong one can rust your engine from the inside out, leading to cooling jacket blockage.
- If your car has any work done on its cooling system, ensure all parts are compatible and working well. Use a workshop that specializes in your make of car to avoid getting dodgy or false replacement parts.
- Check over your cooling system regularly. Learn the signs of damage in the hoses, pump, and thermostat and keep an eye out for them. Replace anything that breaks.
How to Use a Head Gasket Sealer
It is very important to bear in mind that using a head gasket sealer incorrectly won’t only fail to repair a rupture, but may further damage your vehicle. Make sure that your head gasket sealer of choice is safe for your vehicle. Check:
- The cylinder number recommended for this sealant.
- The particle content in this sealant.
- Whether this sealant is advised for small or large breaks.
Once you’re sure you have the right sealer for the job, check the instructions. Most advise pouring straight into the radiator cap, but some require a flush, and others are applied externally to visibly damaged head gaskets. Always follow manufacturer instructions. Within an hour your car may be fixed. However, as mentioned before, bear in mind that this will only be a temporary patch on large breaks, and that if there is internal damage, you may blow a head gasket again.
Our Top Pick
As for our favourite? It has to be Bar’s Leaks HG-1 Head Seal Blown Head Gasket Repair. It’s a highly versatile product, useful for most common vehicles, and not too expensive to buy and keep in your car. It fully seals most small cracks and will hold your big leaks together potentially for over a month whilst you get everything in order. If you have a more delicate car, an older car, or a supercar this may not be the sealer for you. But for most of us, this product is an essential car-care item to carry in our vehicle at all times.
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