I suppose that many of you who are now watching this video knows this weak link of these m52 aluminium blocks. Which is head bolt threads that will strip easily. Especially if the engine overheats. To fix the problem there is HeliCoil sets available. But as you can see, those wont hold for very long time. In this case, the HeliCoils have raised from the block and the result was cracked head. The better way to fix the threads is Time-serts. The manufacturer has set for m52 alu blocks which has everything you need. Unfortunately these cost about 500 USD which is 600-700€ shipped to Finland. I have found cheaper places to buy these sets but even those will cost about 500€ shipped to Finland. But after some googling I found that the manufacturer has universal set with same thread as in m52 head bolts. The only difference is that this set will leave the inserts flush to the deck surface and not 6mm below as they are in m52 block. These sets only cost about 100 USD so when shipped to Finland the cost will be little over 100€ And I decided to order that cheaper set. The inserts that came with the set were wrong for m52 block, but you can order the correct ones separately. Eventually the set + inserts were about 120€ delivered. Here you can see the drill bit that comes with the set. Which is just long enough for the job. Next one is the tapping tool. That one is also long enough for the m52 longer inserts. Next one is the counterbore tool which leaves the inserts flush with the deck surface. I tried to modify this so that inserts would be that 6mm deep in block but that didn’t work out as you can see. So I will just use regular 14 mm drill bit. Maybe the 13 mm drill bit would have been better, but that was the one I had. And the last one is tool to install the inserts. It’s some kind of cone shaped toll which spreads out the inserts so they will stick in. And here you can see one of the longer inserts for the m52 block. Also you will need caliper. And last thing you need is tapping handle. First thing to do is to measure how deep you have to drill. And then mark to drill bit how deep was the original thread hole. I also measured that are the original threads really that 6mm deep from deck surface. And yes they are. So the inserts will have to be 6mm deep in block. Before drilling it makes sense to clean the deck surface and cover all the holes, so that shavings don’t get inside the block. I used brake cleaner for this but here is other suitable cleaning solutions also. Clean the surface carefully so that the masking tape will stick. Next remove all parts that are in the way. And finally add masking tape. I also marked all the head bolt holes, so I don’t accidentally drill wrong hole. Next I installed the drill bit to bench drill so that I can’t drill the hole too deep. This was quite tricky with sh*tty drill like this. And then we drill. The drill bit only removes old threads and no other material. And remember to blow out the shavings. And then repeat this 13 times. When every thread is drilled, it’s time to make the counterbores. I also did this so that the drill bit can’t go too deep. I set the drill bit to go 7 mm deep so that there is room for the inserts collar to fit. So as results the new thread should start 6 mm deep. And here are the counterbores ready. Next we tap the new threads for the inserts. Insert the tap to tap handle. Oil the tap. So the tap wont stuck. And then start tapping the thread. This will take some time, so lets fast forward. Remember to take the tap out few times and clean the shavings. Also add more oil to tap after you clean it. That will prevent the tap from ruining the threads or getting stuck. This is the slowest and most annoying step in the process, because you have to pull out the tap several times. And repeat the tapping 13 more times.. When the tapping is complete, clean the threads carefully with brake cleaner and pressurized air. Only blowing out the shavings isn’t enough because you have to get oil and other dirt out, so that the insert will stick. And here you can see the tapped threads and countersunks ready for inserts. Last step is to install the inserts. To do that put the insert tool to tap handle and oil the tool. Then crew the insert to tool. The insert doesn’t have to go all the way. Then add some loctite to insert. You don’t need to add crazy amounts of loctite. And screw the insert in. The insert will stop eventually when it reaches bottom of the counterbore. But after that you will need to keep rotating the tool, so that the cone shaped insert tool will spread out the insert. And this how the installed inserts look. Lastly we will measure how deep the inserts are. They are 5,5 mm below the surface, but I think that’s enough.