Wednesday, October 8, 2008

Removing valves from cylinder heads

Tonight I worked on the cylinder heads. The Subaru 2.2 is a Single Overhead Camshaft [SOHC] engine, so I needed to remove one camshaft from the top of each cylinder head.

Next I removed the valves from the cylinder head. The valves are held in place by valve springs and horeshoe-shaped 'keepers' that encircle the valve stem.


To remove the keepers, yout need a valve spring compressor to release the tension on washer that holds the keepers in place. I have one, but it wouldn't work because there wasn't enough space to fit betwen the valve springs and the side of the valve covers. So, I used a open ended wrench, pressing down on it until the tension on the keepers was released. Then using a magnet that I held in my teeth [it's attached to an extendable metal rod], I would pick up the keepers. This worked fine for the removal, but I will need another system when I reinstall the valves.

With the valves out, I can tell that the valve seats, valves and springs are all in good shape. I can also see that the valve stems seals were pretty brittle. Since the engine was low mileage but about 14 years old, but age and mileage has contributed to this. So, for $16 and my time, the new valve seals will prevent the enging from smoking when it is started.

When all was disassembled, I sprayed the cylinder heads with some Dawn Power Dissolver water-based degreaser and blasted them clean at the car wash. I am amazed how clean and new they look.



Considering the car had about 65K miles, the valves looked pretty good. Still, I got some valve-lapping compound [a fine abrasive] and used it to ensure that the interfaces between the valve faces and valve seats are nice and tight. I think it will help the compression also.

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