K-Seal ULTIMATE Head Gasket Leak Repair

Save hundreds or even thousands of pounds compared to a workshop repair!


The solution is in the blue bottle.

From the global specialists in coolant leak repair, K-Seal ULTIMATE permanent head gasket repair is the preferred choice of motor stockists and their customers. Why?



  • Fixes blown head gaskets, cracked heads and blocks.  Also, repairs porous blocks
  • Guaranteed to make a repair or your money back*
  • Mixes with all types of antifreeze and coolant so there’s no need to drain or flush the system before or after treatment.  You can also use it with just plain water.
  • Independently tested by Brighton University to meet the US standard ASTM D-3147
  • Simple to use!  Just shake, pour and drive.

Does K-Seal ULTIMATE really work?

Absolutely!  The ceramic micro-fibres in the formula are carefully produced so that they will seal leaks up to 0.635mm in size (but most coolant leaks are in fact much smaller than this).  These micro-fibres will naturally migrate to the pressure differential caused by the coolant leak or failure point.  The leak is repaired and the ceramic ingredient cures to make a long lasting repair.  But don’t take our word for it, K-Seal has been independently tested by Brighton University Engineering Division to meet the coolant stop-leak standard ASTM D3147.  K-Seal is the only coolant leak repair product to have been independently tested by a university to meet this standard.

Will K-Seal ULTIMATE damage or clog my engine?

No.  Part of the strict requirements of ASTM D3147 is that a coolant stop leak product should pass through a filter of 0.85mm without clogging or gelling.  This ensures that the product will not block even the narrowest passageways in the cooling system.  Independent testing at Brighton University has proved that K-Seal ULTIMATE meets the ASTM standard and is safe to use in all types of cooling system.  Note: If you suspect that your cooling system is already blocked or restricted then first clean and flush the system before using any stop-leak additive.

Will K-Seal ULTIMATE work on my car?

Yes.  K-Seal ULTIMATE is suitable for use on all water cooled engines regardless of fuel type, age, engine size or power.  You can use it on anything from a bike to a locomotive, a Ford Model T up to the latest Mondeo.

Does K-Seal ULTIMATE mix with antifreeze?

Yes.  K-Seal ULTIMATE is designed and tested to be compatible with all types of antifreeze / coolant formulas.  Unlike other products it is not necessary to add a particular type of antifreeze for the product to work.

Can I use K-Seal ULTIMATE if I just have water in the system?

Yes you can.  K-Seal ULTIMATE does not need antifreeze in the system in order to make a repair.  In fact it is the perfect emergency head gasket repair as you don’t need to worry what additives are already in the cooling system.  Just shake, pour and go!

What will K-Seal ULTIMATE repair?

K-Seal ULTIMATE will fix coolant leaks in the head, head gasket and block, including porous blocks.  K-Seal ULTIMATE will not repair oil leaks.

How much do I need?

K-Seal ULTIMATE is fantastic value for money.  1 bottle is sufficient to treat leaks in all cars and SUVs / light trucks.  For larger engines simply use 2 bottles.


K-Seal ULTIMATE will repair most leaks in the head, head gasket and block and has a very high success rate.  If K-Seal ULTIMATE is used as directed and does not successfully repair the coolant leak, or a repair made with K-Seal ULTIMATE fails within 28 days, then we will provide a refund of the original purchase value or a replacement bottle.  In the event of a claim simply contact us via our website www.kseal.com or email info@kseal.com with your full contact details, proof of purchase from an authorised K-Seal reseller, vehicle details and a description of the original problem.  We will also need proof of the original coolant leak problem which could be a VAT repair invoice from a workshop, or a mechanic or breakdown report.  Any claims must be received within 28 days from the date of purchase.  1 claim permitted per vehicle.

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K-Seal ULTIMATE Head Gasket Repair

Got a question about K-Seal ULTIMATE? Read our FAQs or Contact us.
Unsure how to stop your car leaking? Use our troubleshooter.

*K-Seal ULTIMATE Guarantee