Rick's Free Auto Repair Advice

Fix a Head Gasket Leak with sealer

Fix a Head Gasket Leak with sealer

Does Head Gasket Leak sealer work?

If you’re constantly topping off your coolant and can’t find any trace of an exterior leak, you may have a blown head gasket. Or, if your engine overheats and you’ve checked the radiator, fans, and water pump, you may have a head gasket leak. Either way, you may be considering a head gasket leak sealer. Everyone wants to know if they work. Well, some sealers work. Others don’t. And the price has nothing to do with their success rate. I’ll give you the whole truth about head gaskets and sealers. Or, if you want to skip the lesson and get right the to the heart of the matter, scroll down to head gasket sealers.

Head gaskets can fail in many ways. First, the gasket can allow coolant to enter the crankcase. The coolant turns your oil milky-white like a milk shake and that destroys your entire engine. To check for that kind of leak, just pull the oil dipstick and examine the oil. If it looks like a milk-shake, you’ve found the problem.

The second way they can leak is by allowing oil to enter the cooling system. That happens because oil pressure (up to 60-psi.) is greater than cooling system pressure (15-psi. Max), so the oil forces its way into the coolant. To check that, yank the cap off your radiator or coolant reservoir bottle and look for an oily film floating on the top.

The third way head gaskets can leak is to allow coolant into the combustion chamber where it’s burned. That’s much harder to diagnose. The coolant simply disappears in the exhaust. On the way out, it damages the oxygen sensors and can destroy the catalytic converter. Some people say you can see white smoke coming from the tail pipe. But that’s not always noticeable. It all depends on how hot the catalytic converter is at the time. The best way to diagnose a heat gasket that’s leaking coolant into the combustion chamber is to conduct a compression test and a cylinder leakdown test. You can also perform a combustion gas test.

Once you’ve determined that the head gasket is leaking, you’ve got a few choices. Replacing the gasket is the most permanent fix, but it’s going to be expensive (at least $1,000). So you may be tempted to try one of the liquid head gasket leak stoppers on the market. Well, ok, let’s talk about those.

Head Gasket Sealers

Head gasket sealers work by plugging the leak with wood pulp, pepper, or by forming a bridge between the gap with next generation nano particles. Obviously, the finger in the dike is the oldest and cheapest method. They may work in a cooling system where the pressure is less than 15-psi., but they don’t work very well in holding back cylinder pressure that easily runs up to 150-psi.

So the first thing you should understand is that you can forget about using cheap head gasket sealers (anything costing less than $30). First off, most of those sealers are incompatible with coolant. So you have to drain the entire (and I do mean the entire) cooling system and refill the engine and radiator with plain water. That means radiator, heater core, and block (pulling the block plugs) have to completely drained and refilled. Then you pour in the stuff and run the engine for the specified time. Then you have to drain the system again and leave it open to the air for 24-hours. Then you can refill with coolant. These sealers work way less than 50% of the time. They’re a lot of work for such a lousy payback. And, as with most head gasket sealers, the leak must be small enough to allow you to run the engine for the specified period of time. If you have a large leak that’s rapidly pumping coolant into the crankcase, you’re not a candidate for ANY head gasket sealer (no matter WHAT the manufacturer’s guarantee says).

Next, you have to be very carful with plug type sealers. Everyone online will tell you they plug up the radiator and heater core. Well—they can, but only if you don’t follow directions. Keep in mind that the fin tubes on heater cores are VERY small. If you overdose any cooling system with a plug type sealer, it will clog the fin tubes. In this case, more is NOT better.

Then there are the next generation sealers

Bars Leaks HG1 or CRC’s KW FiberLock sealer are the newer nano-technology sealers. Bars head gasket sealer, Bars leaks, head gasket leak
Head gasket sealer, Fiberlock, Bars leaks CRC These work with a 1-2 punch. First, they contain a plug sealant that forms a “finger in the dike” patch. Next, the temperature sensitive chemicals attach to the plug material and melt to form a “permanent” seal. The nano particles form a patch along the hottest areas of the head gasket and continue to build until the breach is sealed. Nano particles don’t work inside a radiator or heater core—there’s not enough heat there. If your engine is a candidate (see below), these products work 80-90% of the time. Just pour them directly into the radiator (not into the coolant reservoir). You may have to disconnect the upper radiator hose and siphon out some coolant to do this.

Which engines aren’t good candidates?

READ THIS: If you’ve overheated your engine and warped the head, you’re deluding yourself into thinking that a head gasket sealer will fix that. With a gap between the head and block and expansion and contraction during normal heating and cooling cycles, no sealer is going to stick. Then again, you’ve got very little to lose by trying either of these products. Just realize up front that you’re most likely going to end up paying for a head machining and a new gasket.

Now let’s talk about the real candidates.

If your engine will run for at least 20 minutes without overheating or losing most of its coolant, these products MIGHT work for you. These are engines where the head hasn’t warped, but the head gasket has deteriorated due to pre-ignition or corrosion (not overheating). For these engines it’s worth a shot and the sealers often have an 80% success rate.

How about the more expensive head gasket sealers—the ones that cost almost $100?
Well, how do you feel about being taken to the cleaners? Scammed? Played for a sucker? Screwed? Get my point? You don’t need to spend that kind of money on a head gasket sealer. If a sealer is going to work, either of the two products above will do the job just fine.

If the sealer stops the leak, you’re done. You do not have to add additional sealer down the road when you change coolant.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat


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