Rotary Gear Failure

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Engine seized up on my 99 GTI a couple summers back. Decided to break it down and found that the brass rotary gear was stripped and the rotary valve was damaged.

I’ve read that mostly this happens when the valve ingests something. When it seized I had just had the carb rebuilt a month or so before so that is possible but I can’t find anything in crankcase other than the brass shavings. The crank looks good and seemed well lubed. The gear in the oil pump has missing teeth. Could that hard plastic have broken off and caused this?

Any other common causes of this? I’d like to clean the crankcase and put it back together but don’t want to just for this to happen again.



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It ingested something hard because you can see the damage on the cases. Hopefully whatever it was isn’t inside the cases so you better split them and see.

Also you need to inspect the oil pump, never seen an oil pump gear strip like that.
I did split the cases and found nothing inside other than brass shavings. Any other possible causes? I don’t want to put it back together just for it to happen again.
You had something get stuck in the rotary valve, whatever it was.

You’re correct. I broke everything down further last night and found damage in the exhaust port side of the engine. Looks like whatever went through the valve/gear did damage on the way in and the way out.
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