How can you tell if your car has a cracked head?

Answer 1

There are several ways to tell if your vehicle has a cracked head. Common symptom of a crack on the side of the head is that after the vehicle warms up it will spray oil all over the inside of your engine compartment. If the crack is on top of the head under the valve cover it may be harder to notice. You will lose compression on one ( or possibly two ) of the cylinders so the engine will be sluggish and not make it up a hill or maybe out of your driveway ( again after the engine is hot ). You won't see the oil leaking because it will be coming out under your valve cover. If the heads are steel ( most modern cars use aluminum), taking the head to a machine shop to be milled is a good idea. The steal becomes magnetized when it is milled and metal shavings will stick to any crack. Usually a crack on the top of a head occurs between two exhaust valves that someone engineered to be next to each other. If a crack occurs on the bottom of a head you could end up with water in your oil. The oil on your dipstick will be milky white. This is also indicative of a failed head gasket. If there is a crack between two cylinders ( unlikely but not impossible) you will be losing compression in those two cylinders.

Noticing the loss of power after your engine is hot compared to when it is cold is one clue. Remember this condition could be symptomatic of other problems. If you compression test your cylinders, when the engine is cold of course, and find no problem but still lose compression once the engine is hot you can eliminate a stuck valve as the cause.