Should I fix it?

Can a blown head gasket be fixed without replacing it?

Yes, for most engines that qualify. Chemical head gasket repair was invented in 1995 by chemist Robert Hooper, and the same company has been improving it since. More than 1,100 repairs by one field technician are on video. Here is who it works for, who it does not, and what "fixed" means.

What a chemical repair is

Instead of pulling the cylinder head and replacing the gasket, a chemical repair seals the breach from inside the cooling system. The engine has to be running for it to work, and the process has rules: the cooling system is flushed with plain water first, including the heater core, because the repair solution does not mix with antifreeze. Then the engine runs for at least 15 minutes with the solution in it, and you finish the cure over the next three days by bringing the engine up to operating temperature at least four times. After that you flush again and go back to antifreeze.

The step by step instructions are public: Easy repair instructions.

Is it permanent?

People say a bottle fix is a band aid. Some are. The Thermalweld process and solution are designed to be a permanent repair, and the guarantee is written that way: 30 days money back if it does not repair your head gasket, cracked head or block, then for as long as you own the car a fresh treatment for $25 shipping and handling if it ever fails. The public record is 1,100+ field repairs on video and a published 95% success rate. Customers on the reviews page report how far the car has gone since.

Why most bottles fail, in the inventor's words

That is the whole difference. A product you can pour into antifreeze and drive away has to be mild enough to live in antifreeze. A product that can actually close a breach cannot be, which is why the flush comes first. Dave's own answer to "what makes yours better" is shorter: many people try something else first, and after it fails they call him. Where they failed, he fixes it.

Which engines qualify

• It starts and runs, even if it runs rough. It has to run for at least 15 minutes.
• It is losing coolant, with or without visible white smoke. Under a quart per 100 miles is not a major breach.
• The oil is clean, or the oil cap is milky and the dipstick reads at the full mark or an inch or two over.
• If it overheated, you know why, and that part has been fixed or will be.

Which engines we turn away

• It will not start, or will not turn over. If it cannot run, the process cannot work.
• The dipstick reads five inches or more over the full mark. That points to other damage, possibly a cracked block, and tech support will talk it through with you before anyone spends a dollar.
• It keeps overheating from a cooling system failure nobody has fixed. Repair that first or the new seal fails the same way.

Dave shows the ones he says no to: Head gaskets that are too far gone.

Is it worth fixing?

A shop charges $2,000 to $7,000 to replace a head gasket, if they will do it at all; many will say they do not do head gaskets, just replace the engine. A Thermalweld kit for any 4, 6 or 8 cylinder gas engine is $129 and holds two treatments. Hybrids are $109. Northstar and diesel kits are priced on the price table.

Full breakdown: Head gasket repair cost.

Will it clog my radiator or heater core?

No, as long as you flush the antifreeze out first and flush the solution out afterward, heater core included. The solution does not mix with antifreeze, which is why the water flush is not optional. You can go back to antifreeze after the repair once the solution has been flushed.

Before you buy anything

Confirm it really is the head gasket. A parts store will lend you a block tester and the fluid is about $10: How to do a block test. Then run the qualifier below. Not every engine qualifies, and the 60 seconds tells you whether yours does before you spend a dollar.