08-01-2015, 08:10 PM
Some of you may recall a post earlier this year about my Mum's 1.9TDI Astra shredding its timing belt and introducing the valves to the pistons. Well it has been a long and often complicated process, as there are virtually no major parts available here (Holden imported about 2000 of this model into Australia), some parts sourced overseas had slightly different components and one part I had to make. I've also been away with work at various times.
Two weeks ago I was torquing up the camshaft bearing cap bolts and one chewed up the thread in the head. These threads are M7x1 and none of the auto parts stores stocked Helicoil kits in that size. One said they could get them in but then didn't. Ordered last week from a different supplier and got them yesterday. I had considered simply going to a M8x1.25 but the hollow locating dowels that the bolts pass through are too small. In fact, they were too small for the drill and tap needed for the helicoil, so I had to figure out how to get them out. Fortunately, I have the scrap head that came off the car. I discovered quickly that these were rather fragile and pliers wouldn't work.
I decided that I could lightly tap them and then use a slide hammer to pop them out. Trouble is that my slide hammer was at home. I did have another at my Mum's but the end was missing (I've been meaning to make one for ages). The thread is 1/2-13 and all my US taps are also at my home. So I found some scrap that suited and welded a 1/2-13 nut to one end. The other end already had a hole in it, which was suitable for a M12 thread. I had some M12x1.75 all thread on hand so I tapped it to suit. I then turned down a section of thread and (using a die) I cut a M8x1.25 thread. It doesn't look too pretty but it worked a tread.
Next I made a drill guide, which was interesting to make as the inside diameter is 9/32" (0.218) and the outside is just a touch over 7mm (0.276).
Sorry for the crap pics, I was using my phone. The good news is that the bolt now torques down, so that job is finally done. Now I have to remove the new hall effect sensor for the cam from the bracket that it is mounted on, so I can put it on the bracket that came off the car...
Two weeks ago I was torquing up the camshaft bearing cap bolts and one chewed up the thread in the head. These threads are M7x1 and none of the auto parts stores stocked Helicoil kits in that size. One said they could get them in but then didn't. Ordered last week from a different supplier and got them yesterday. I had considered simply going to a M8x1.25 but the hollow locating dowels that the bolts pass through are too small. In fact, they were too small for the drill and tap needed for the helicoil, so I had to figure out how to get them out. Fortunately, I have the scrap head that came off the car. I discovered quickly that these were rather fragile and pliers wouldn't work.
I decided that I could lightly tap them and then use a slide hammer to pop them out. Trouble is that my slide hammer was at home. I did have another at my Mum's but the end was missing (I've been meaning to make one for ages). The thread is 1/2-13 and all my US taps are also at my home. So I found some scrap that suited and welded a 1/2-13 nut to one end. The other end already had a hole in it, which was suitable for a M12 thread. I had some M12x1.75 all thread on hand so I tapped it to suit. I then turned down a section of thread and (using a die) I cut a M8x1.25 thread. It doesn't look too pretty but it worked a tread.
Next I made a drill guide, which was interesting to make as the inside diameter is 9/32" (0.218) and the outside is just a touch over 7mm (0.276).
Sorry for the crap pics, I was using my phone. The good news is that the bolt now torques down, so that job is finally done. Now I have to remove the new hall effect sensor for the cam from the bracket that it is mounted on, so I can put it on the bracket that came off the car...
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