Adjusting the upper timing chain

A story I would like to share with my Jaguar friends, especially those with six cylinder XK engines.

I have discovered how to have a heart attack without even trying. Yesterday I decided to adjust the upper timing chain on my newly rebuilt engine now that I have 2000 miles on it. No real significant reason to adjust the chain other than I could hear a little chain noise after engine start. This is a real easy adjustment to make and easy to do. It only requires removing of four acorn nuts that hold the breather cover in place which is also the access cover to the upper timing chain adjustment mechanism. As many of you know the adjustment mechanism is a concentric gear that by rotating counter clock wise with a special adjustment tool (that I have) the chain tension can be adjusted as required. To do this only requires loosening the locking nut and placing the tool on the gear; or so I thought. It seems that my tool would not go over the locknut. No problem I thought, I would just carefully remove the nut so the tool would fit tightly on the adjustment gear. So being especially careful to make sure I didn't drop the nut down inside the engine I removed the nut and adjusted the chain. It wasn't real loose but a couple of clicks on the gear snugged it up.

Now it was just a matter of replacing the nut, reinstalling the cover and I would be back in business. So I very gently picked up the nut and as I was positioning it on the threaded gear it slipped from my fingers and fell down inside the timing chain cover. This could be catastrophic, requiring pulling the engine and rearing it down to retrieve the nut. My only hope would be that I could retrieve it with a small magnet. But not knowing exactly where it may have gone left me with a sick feeling of despair, but I at least had to try to retrieve it. So with a small magnet I started to gently lower it down inside the cover. I then gently retrieved the magnet to find nothing attached to it. So again I gently probed around and as I pulled the magnet back, low and behold was the nut. No heart attack this time, but tremendous relief. So now it was just a matter of trying to reinstall the nut without dropping it again.

A a security measure, I stuffed a small shop rag inside the chain housing just incase if I dropped it again it wouldn't fall back inside the engine as before. This time the nut went back in place and I torqued it down I said to myself "Thank you". Now it was just a matter of reinstalling the cover and starting the engine to see how it sounded; which was as I had hoped, smooth and quiet.

One thing I might do if I have to do this again is to insert a small screw driver in the hole that is in threaded shaft the nut is on. Then the nut would always be captured on the shank of the screw driver with no way to fall off during the removal or installation.

I hope you enjoyed my story and hope it might help you if you ever have to do the same task.

Dick
70 E-Type OTS