Recently my car lost oil pressure and blew out cylinder 2 & 3 spark plugs. My first thought was that the timing chain was broken. I took off the valve cover to discover, from what I saw, the timing chain was intact. Can anybody provide me with any insight of what a potential cause could be? I also thought that maybe the timing had jumped way off because of a faulty tensioner , but i have yet to dig that deep.

Thanks in advance

 

While I have no great insight into the cause, I can tell you that this is not uncommon.

My R53 blew out the number 3 spark plug repeatedly, stripping out the threads in the head and necessitating installation of a time-sert thread replacement.

When this happened, I looked for answers on NAM. I found many posts about ejecting spark plugs and stripped threads, and many posts indicating that time-serts are the best method of repair - but few clear suggestions for the cause of the trouble.

Sorry I can't be more help. But if you do end up needing to put new threads into the head, I'd be happy to sell you the time-sert tools and extra inserts I have on hand.

 

Mine did it on #1. Why did it came loose? I have no idea, I've changed hundreds of plugs with no problems before. Maybe it's something to do with thermal expansion between the head and the plugs that's weird compared to other cars, more heat or something, hell I don't really know.

One thing is sure is that I fixed it with a TimeSert and it's fine since them. I don't trust helicoils for spark plugs, but TimeSert is a full sleeve with threads inside and out, so no flimsy parts there.