K-Seal Coolant Leak, 236ml | Multi-use Car Radiator & Head Gasket Repair Sealant

It’s amazing stuff. Sorted a mysterious coolant leak in minutes. First time since I got the car that I haven’t had to top up after a long journey. Seems to be a permanent fix too.

Was loosing coolant with no visible leaks.Put this in when I topped up and level ain't gone back down so all good. Seals any hairline or non visible cracks great

Had a significant leak from the heater core into driver's footwell. Subsequently the engine was overheating due to lack of fluid in the system. Had this same problem two years ago and replaced the matrix for about £180... I was unwilling to replace it again on such an old car so a mechanic suggested trying K-seal which he used on his own van! With nothing to lose (the car has high mileage and no value except to me as a run about) I poured a bottle in, topped up the coolant levels and went for a drive. I also turned the heater/fans on to allow plenty of fluid through the problem matrix. Went from a steady trickle to no drips after about 10 mins (you need to give it time to work through the system and do its job at operating temperature to work, and it says a bit longer if added to to the expansion tank as I did). Worth noting that coolant levels may still drop a bit after using this due to air locks in the system so expect to top up the coolant a couple of times after use and therefore a lower level doesn't necessarily mean you are still leaking fluid.I guess it's better to replace the problem part if your car is newer and if it makes economic sense but this is a cheap fix for an old car that doesn't owe me anything and so far so good!

Amazing stuff! My wife's car was losing 2 litres of coolant a week (no idea how/where). I put this in the system, topped up with coolant and after 2 weeks the level hasn't moved.

Excellent cure for vehicle coolant leaks. Solved my son’s water pump leak when I doubted it could possibly do the job. Still going strong months later!Great price on Amazon.

I purchased a bargain car that I knew would require some work to put it right. When I purchased the car the engine was lacking power and the idle speed was hunting (going up and down). As the engine oil was ok I thought I'd try cleaning out the fuel & exhaust system first using Injector cleaner, turbo cleaner fuel additives and diesel particulate filter cleaner additive to burn off any soot built up in the exhaust. After I'd tried all of those each one on a full tank of fuel I'd probably done 1,500 miles and the car had more power and the idling had improved. I then noticed the car had started to lose approximately a pint of coolant over 10 miles and I think there was a slight whitish haze in the exhaust smoke which shouldn't be there as the car is a diesel. I wondered whether I'd caused the coolant leak by using the fuel additives as they contain detergents. I suspected the coolant may be escaping via the head gasket or maybe via the exhaust gas recirculation cooler into the exhaust so decided to try K-Seal. At first I thought the K-Seal had fixed the leak but after a couple of days the car started smoking again and the coolant loss was about the same as before I had tried the K-Seal. Unfortunately during those couple of days the K-Seal had made a proper mess inside the coolant header tank and as the header tank is made of white plastic lots of copper particles and gunge can now be clearly seen coating the inside of it above the coolant fill level. I have since wondered whether the previous owners may have already used a leak repair to hide a head gasket problem and if so whether it would have impaired the efficiency of this product but have no way to know if that was the case. I decided to try one more cheap fix before considering a garage repair so purchased a competitors product that was cheaper than K-Seal and does not contain all the copper particles. The cheaper product has currently stopped the coolant loss but it would have mixed in with any remaining K-Seal in the engine block so maybe they are complementing each other now. In conclusion, this probably does work in many cases but in my case, it didn't work. I am pretty sure that in many other cases it probably also makes a proper cosmetic copper splattered gunge mess inside the header tank. In hindsight, I think I'd only try the K-Seal again if I could add it directly into one of the cooling pipes so the whole bottle doesn't start off in the header tank or alternatively I'd add it to a warm system so the thermostat would already be open. Also if there is ever a next time on another vehicle personally I'll try the competitor's product first as it was cheaper and didn't make a mess inside the header tank.

Writing from the UK, in December 2022Toyota Auris, 2.0D4D, 2008, 85,000 miles.Had developed a quite significant coolant leak from around the waterpump pulley area - enough to have to top up entire tank weekly. No noise however.With the engine running, I could see droplets of coolant being thrown out from behind the pulley (using a good torch).Tried the K-Seal - according to the instructions - which for me was half this little bottle.After just one drive (30 miles) - the leak had definitely stopped!Now my only concern is - obviously a chemical treatment can't fix a worn bearing (if it is - as opposed to merely a worn seal) - but I'm expecting it to make at least some noise before it's about to do anything catastrophic.A new pump from Toyota was surprisingly cheap (c.£150) - so I will change it out soon.But - where all I have is a worn seal - then this stuff really will buy you thousands of miles, if not tens of.And heck - with it circulating throughout the entire rest of the system - it is also preventive maintenence for any other types of leaks (say heater core).

I bought this hoping it would fix a small coolant leak in my car.In terms of effectiveness it just did not deliver. The leak was still there after I used it and I saw no improvement at all.Ease of use was fine. It is simple to pour in and let it run through the system but that only matters if it actually works.When it comes to value for money I felt like I wasted it since I will still need a proper repair.The quality is hard to rate. The bottle and packaging were fine but the product itself did nothing for my situation.Maybe it works in some cases but for me it was a total miss.