Thermagasket Extreme Duty Head & Block Sealant

Thermagasket Extreme Duty is a professional head gasket and block sealant for large gasoline and diesel engines with high capacity.

It is designed for cooling systems exceeding 7 gallons. This advanced solution provides a reliable fix for heavy-duty engine leaks today.

This two-part formula combines a 32 oz Extreme Duty Base Formula (Part A) with a 16 oz Catalyst (Part B) for maximum sealing power.

Together, they create a powerful sealing system. It is designed to repair blown head gaskets, cracked cylinder heads, and block leaks.

It also stops coolant loss issues and internal leaks. It effectively seals combustion gas leaks to keep your engine running at its best.

Unlike temporary stop-leak products, this formula handles demanding applications. It is ideal for heavy-duty trucks and commercial vehicles.

It works for diesel pickups, industrial equipment, and RVs. It gives your engine a head start on recovery with professional-grade results.

Benefits of this Head Gasket and Block Sealant

• Designed for engines with 7-gallon cooling system capacity or larger

• Compatible with both gasoline and diesel engines

• Professional-strength two-part sealing technology

• Helps restore engine performance and cooling system integrity

• Ideal for heavy-duty, commercial, towing, and high-load applications

• Easy-to-follow application process

What's Included

• 32 oz Thermagasket Extreme Duty Formula (Part A)

• 16 oz Thermagasket Catalyst (Part B)

Using this sealant is like understanding the anatomy and physiology of your engine. It ensures you fix the core issue the right way.

Whether you manage a fleet or a single rig, the reliability is as steady as the s and p 500. It delivers consistent, high-end performance.

If you need a diesel head gasket sealer or heavy-duty coolant leak repair, Thermagasket Extreme Duty is the trusted professional choice.

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What Diesel & Heavy-Duty Owners Are Saying

"I called last year before Christmas when my 1995 Kenworth with a 460 HP Cummins Turbo overheated and blew a head gasket. I was about 800 miles from home!... As of August 1st I have clocked 90,000 miles on my truck since the repair without a hint of problems. The engine has about 350,000 miles and is running great. I keep a kit in my truck at all times just in case."
— Billy W, Omaha NE

"I have a d466 International diesel truck that had a huge amount of water getting in the oil... it just about quit steaming that first day and after the second treatment the engine has nothing coming out of the blowby tube but a little blowby."
— Mike Labriola

"Just wanted to say it worked in my 85 Ford Diesel, I have been plagued with this head gasket problem for years and in one application your product fixed it."
— Gary Meek

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