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Lets talk about..... Bent Valves

2323 Views 3 Replies 3 Participants Last post by  scottfree
For everyone who doesn't bother to read the introductions, I just bought a 99 SOHC that jumped time. I took it apart and discovered that the passenger side head is 90 degrees (ccw if it matters) out of time.
My question is, what are the odds that the valves are bent?
Here is the data.
90 degrees out of time (timing mark at 9 when should be at 12)
Pulled the spark plugs, nothing appeared to hit them

Did I get lucky? Or is there some other way to check?

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Should go without saying, timing the engine should be done first. The marks do not come up to TDC, the correct marks would have the piston down in the bore to clear the valves as the cam is turned.

That also confuses diagnosis - again, the marks do not show up at TDC. They are set up to clear the valves and pistons for trouble free assembly.

It IS an interference motor, Subaru did the right thing and is trying to keep putting on a new belt from creating damage. It's not like conventional timing with chains on a 'nobendum" motor.

Once it's back in time - if it was out - then a compression check is in order. Cylinders should be within 20% at the worst. It can be done again with a small squirt of oil in the cylinder to help seal the rings, which will should how much the valve seats are leaking in comparison. A bent valve will likely not even let the motor come up with compression. It's hanging open.

During that first rotation after the timing is done, be very careful to feel for ANY obstruction or sudden increase in pressure. That may very well be a valve bent hitting the piston. If a fisheye engine cam is available to rent, seeing inside the combustion chamber thru the spark plug hole verifies things quickly, for good or bad.

Just watch the timing marks, Subaru didn't do it like "normal." They marked them to prevent damage while getting it timed.
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