Do you know what the head gasket is for? Its main job is to create a tight seal between the motor and the cylinder heads. Without a proper seal, the toxic combustion vapors will escape. Leaking coolant/oil is another strong sign of a damaged/faulty gasket. The list of the side effects/symptoms of a bad head gasket is pretty big and can wreak tons of havoc on your vehicle.
So, in this post, we’ll learn about the most common signs of a blown head gasket and how a regular driver can detect them without special equipment. Now, I highly recommend visiting the local auto/repair shop whenever you see any of the following symptoms, because the longer you delay, the bigger the problem(s) will become.
We start with the most expensive, hard-to-fix, and problematic side effect of a faulty head gasket. And the funny thing is – in many cases, gasket failure is actually caused by an overheating engine. Minor coolant leaks, restricted radiators, or malfunctioning fans can cause temporal motor overheating, which, in turn, leads to a blown gasket. And, once it goes bad, the gasket “gets back at” the engine.
When it fails at keeping the heated exhaust fumes from leaking into the cooling system or the coolant from “feeding” into the cylinders, bad things start to happen. Too much heat in the engine bay/combustion chamber can lead not only to engine overheating but also damage the exhaust system (mainly, the catalytic converter).
Sometimes, when the gasket loses its efficiency, it allows the air + fuel mixture to “slip away”. That, in turn, dramatically reduces the compression in one or many cylinders. When that happens, you’ll experience rough, inconsistent performance. Plus, the engine won’t be able to perform at the top of its game. If you hear a clanking, rattling sound, that might be it.
Usually, the fumes, vapors, or smoke coming out from the tailpipe are either grey or black. So, when it’s actually white, that’s a clear sign the head gasket needs to be replaced. The smoke cloud will be pretty big, by the way, and it will have a sweet odor. As you might already know, the coolant/antifreeze has a smell that resembles a baked cookie. And, when it makes it through the gasket and into the cylinders, you’ll instantly smell it.
The cloud of steam/smoke will be another big sign, which makes this the most obvious and easy-to-detect symptom. In some rare cases, the smoke can be partially blue. This happens only when there’s a leak from one of the oil passages into the combustion chamber (or, rather, the cylinders). If some of the radiator hoses have blown off, or the dipstick isn’t “sitting” steady, I bet the gasket is to blame.
This is known as oil contamination; some mechanics call it the milkshake. I’m talking about when the antifreeze and the oil get mixed up together. That can be caused by many things, but, mostly, it’s the head gasket’s fault. The best thing you can do in this situation is to flush the motor’s oil and refill (or, rather, replace) it from a fresh bottle/container. Also, check the engine’s bottom: it might be that the bearings were damaged and need to be replaced as well.
A bad head gasket can cause the cylinders to misfire. When there’s a breach in the gasket, I recommend running a quick cylinder leak test to fix the issue as quickly as possible. Otherwise, you’ll have severe problems with firing up the engine. It might start eventually, but it will, indeed, struggle a lot.
You might think that an external oil/coolant leak is the worst-case scenario, but it actually isn’t. This is the least dangerous sign/side effect of a blown head gasket. It will cause a mess, that’s true, but the engine won’t break down, and you won’t see white smoke. Still, don’t let this go unattended for long, because when the coolant levels drop below the critical level, the motor will overheat. As for leaking oil, it can turn into a fire if it gets into the exhaust!