Toyota Repair: Sienna, poor experience, technical reason

Question
Andrew, I am the owner of the 2000 Sienna with the spark plug problem. Looking down into the cylinder head, there are no threads. The spark plug will now drop all the way to the piston, which can be easily seen and in great condition except for a little, normal carbon build up. The plugs are original, 80,000 miles. It looks like there was some sort of insert in the head where the spark plug threads once were. I suspect Toyota put some sort of a sleeve in the head for some technical reason??? Thanks for your answer and research.

Answer
Hi there,

It is VERY possible that Toyota had a casting flaw in the head at the manufacturers plant. I have seen similar problems like this in the past and was "repaired" by toyota just to get the vehicle to pass inspection. In regard to your issue, my opinion is that the head will need to be removed and taken to a machine shop. In the meantime, you might want to contact Toyota's customer service (found on the internet)...I think it's an "800" number. Tell them about your poor experience and see what they can or will do for you.