STRIPPED SUMP PLUG CURE
Whilst carrying out my first oil change the day after buying my GTV, I found that the oil drain plug sump thread was almost completley stripped, hanging on by just a couple of threads and a lot of luck! Not wanting to remove the sump I took a vernier caliper and measured the internal diameter of the stripped sump drain hole. It was pretty close to the tapping size for a metric 22mm coarse tap. Also it appeared to be about 10mm thick so plenty of meat to re-tap the hole in situ. Working upside down with plenty of grease on the tap to catch any swarf, I used a 22mm 2nd cut tap to cut a new thread, I didn't put the tap through the whole way but paused and removed it every half turn to test fit an easy to get 22mm bolt/screw. Once the new thread was cut I coated the new bolt/screw threads with blue sealant, screwed it into the sump and just nipped it up wrist tight.
To prevent it from coming undone and falling out, I cross drilled the hexagonal head and wired it aircraft style to an adjacent stud/nut. Whole job took about half an hour.
Actually I was very surprised to see that Alfa should use such a fine thread cut into an aluminium casting, recipe for disaster if you ask me. The above method saves the expense of helicoiling and I believe is an improvement, course thread, large hexagonal plug head, and wired so no possibility of it falling out. I must say though if you have never cut a thread before it would be prudent to seek advice or help from an engineer. Also never, never bodge a stripped sump plug by trying to stick it in with glue, sealant etc. No matter what the glue manufacturer claims. Loctite 242 threadlock is intended to secure threads that are in good condition. If the plug falls out when the engine is running it WILL completly wreck the engine in THREE seconds!
Last edited by jonsnapart; 17-11-09 at 12:33.