One of the great mysteries of the internet that everybody has a conspiracy theory about. Well, it’s the Subaru EJ Series engines and head gasket leaks. There are dozens of theories in regards to why the head gaskets can fail anywhere from 75,000 miles to 130,000 miles. The reality of it is, well, it’s a combination of factors and simple physics. With this engine, it’s a boxer engine. In other words, the pistons run side-to-side, instead of up and down like a normal four-cylinder engine. So, if we take this four-cylinder engine where you have the head gasket up here, let’s say that’s the mason lid jar, and then you have the water jacket down below. Let’s say that the bbs in the bottom of here, well those are contaminants. They could be from corrosion, they could be from sludge, it could be from a number of things that could be inside the cooling system.
With this, well, they fall to the bottom. They could damage the radiator, they could also damage maybe the freeze plugs. But, if we configure it, this engine right here to be a boxer engine like in the Subaru, well, you’re going to see a distinct difference to where the corrosion goes. So you’re going to notice this. When we laid it on its side, the contaminants that are inside the water jacket, well, they’re now in contact with our head gaskets. And this isn’t very good for a head gasket, especially if it’s one of the older composite gaskets. Essentially, the gasket is rotting. And other factors, like the engine oil, well that could make the rot even worse for the cooling system and causing the gasket to break down, and even causing exhaust gases to make it into the cooling system. So, be mindful of the service requirements on some of these engines because this is the low point of the cooling system.
So, if you’re getting ready to start on one of these jobs, there’s a couple rules of the road. First of all, make sure all of the coolant is cleaned out of the system, and you may want to flush it a couple of times to make sure there’s no contamination. Also, look at the oil system and make sure that the system has fresh oil. The head gasket, well, it also comes in contact with oil. If the oil is not healthy, clean, well it can cause other issues for the head gasket material.
The other thing that you need to pay attention to is the surface finish on the head. This is typically between 20 and 30 RA. Send it out to a machine shop. Do not use any disk to clean up that surface because chances are you’re going to cause more damage, and you’re going to round off edges that won’t seal properly with the new head gasket. Also, use a high-quality head gasket. In other words, new technology is constantly updating. So, a Subaru that was probably made 20, 15 years ago, well head gasket technology has moved on in that time. And, there’s ones with stoppers, special welding, that can help seal that job for a very long time.
I’m Andrew Markel. Thank you very much.
This video is sponsored by Elring Das Original
