Subaru Burned Valve – Found The Problem!

I recently picked up a great new toy in the form of a 2006 Subaru Legacy GT.  Much like all vehicles that I buy, it needed some major work before hitting the streets again. When I first heard about this car, the local Subaru dealer had just declared that it needed a new engine. Technically speaking, it did still run. However, it was running really rough due to lack of compression in cylinder #3. With the higher mileage that it had, and the repair being a seriously labor intensive job, it just wouldn’t make sense for the owner of the car to have it fixed. For me though, I get a weird thrill over fixing cars that other people condemn. Before long, a deal was struck, and the red Subie landed in my driveway.

The first step of any repair is determining what the problem is. Since I already knew that one cylinder was missing compression, I began the diagnosis by determining where all of that compression was going. I knew that if the piston was damaged, the compression would have to be filling the crankcase like crazy with air, so I started the car and yanked the oil filler cap off. I then waved my hand around above the oil filler tube. If the piston was damaged, there would have been massive amounts of compression pumping out of there. Luckily for me, there wasn’t. This, along with a quiet running engine, told me that the piston & rings were probably in good working condition. Next on the check list, and really the only other option, were the valves. I shut off the car, and installed a cylinder leakage gauge into the spark plug hole. I then set the engine to TDC on cylinder #3, and pumped 90psi of air into the cylinder. Sure enough, all of that air immediately flowed right out the exhaust system. Tada, an exhaust valve was damaged! This meant that the engine was coming out, and the heads were getting pulled off. Most of Saturday came and went, and the picture above is what I discovered.

So what causes burned valves? Well, from what I have read about these engines, the valves aren’t known to be the best quality to start with. Compile that with the fact that the valves were never adjusted in 140K miles (which is rarely, if ever, done by anybody with a Subaru), and the valves were given the opportunity to hang open just enough to burn. Yeap, a total bummer for sure.  This car though, is getting a second chance at life, with new valves, head gaskets, timing belt, water pump, etc.  I cannot wait to get it back together!

More to come in the weeks ahead…

Click Here to See What Happens Next!

 

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