PROJECT 51: Thread repair. Apparently, when the engine was rebuilt in the past, the timing chain was not replaced (!) so it had enough stretch to slap the top of one of the bolts that secures the oil pan to the timing chain cover. In another photo, you can also see where the chain was hitting the cover, itself. The result was that the threads on the end of the steel bolt were mashed, so when it was unscrewed, it tore the threads out of the softer cast-aluminum cover. I was able to open the hole, and tap it with a slightly larger size thread (3/8-24), and then make a steel insert with the 3/8-24 thread on the outside and the correct 8mm x 1 thread on the inside. The insert was then threaded into the cover with high-strength LocTite to keep it from turning during reassembly. As long as I was set up, I put an insert in the other hole, as well.
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| Even with the tensioner (left), the chain had enough slap to hit the end of the bolt that came through the hole at lower right. |
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| Inside of timing chain cover. Gouges are from chain slap. This bolt was also too long; it should not have come through. |
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| End of damaged bolt. |
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| New 3/8-24 tapped hole. |
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| Threaded insert. 3/8-24 outside by M8x1.0 inside. |
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| Part way in with high-strength Loc-Tite. |
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| Seated flush, and stronger that the original. |
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