Not likely a problem from these two different metals touching each other. Think about how many dozens of steel bolts are fastened all over the aluminum engine block and head(s). They all come out just fine.
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Tester
All good suggestions and I didnāt know about roll forming. Take it to a legit shop and not a chain or quick lube place for this job.
Oil pan plugs have a coating of oil so donāt really stick. I have had steel fasteners in aluminum stick in cases where there is a lot of moisture or heat exposure. Lawn mower blocks can be hard to get bolts out of at times.
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Agreed about taking it to a legit shop, although we were doing that. Itās a transmission shop that came to us highly recommended by a friend. They have changed the oil in our CR-V for the past couple of years and weād never had a problem with them before.
Does that work with aluminum? My understanding was that unlike steel, aluminum does not work harden, but gets weaker as it deforms. This is why an aluminum beam fractures instead of bending like steel would.
Aluminum comes in a wide variety of alloys. You are right about dead soft (pure) aluminum but that is not used in engine applications. Most alloys will work harden. 319 and 356 alloys are most common in engine applications with 319 being the most common.
The stronger threads is not from work hardening. It has to do with grain formation and I donāt remember all the particulars except that when you cut threads, you cut through the grains. When you roll form, you reshape the grains to follow the contours of the threads. The threads, when subjected to too much force tend to fracture along the grain lines, which is harder to do when the grain lines are long and go around the edge of the threads instead of being short and only go from one thread to the other.
I used to work in a foundry that cast cylinder heads for Ford, GM and Chrysler. Early on, all the heads were cast in a 319 alloy. Ford started using the 356 alloy in some of its HP 4 valve heads. The 319 was rather brittle, but the 356 alloy was about as tough as cast iron. It was very difficult to remove the ingates (the little wings at the bottom of the casting where the aluminum entered the mold) because it was so malleable. They had to be chiseled off where the ingates on the 319 alloy heads would would just fall off with a light tap of a hammer. The 356 would also have a rockwell hardness at least 10 points above the 319. Because the heat treatment requirements for the 356 were so different from the 319, we could not produce heads in both alloys in quantity, so Ford built a new plant in Windsor Canada just for the 356 which they used in all HP and Triton heads.
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Suggest to peek under vehicle & take a look. Some of those temporary plugs arenāt flush w/pan; instead they hang down below pan surface a little, can get knocked loose by road debris. If so, monitor diligently for oil pressure warnings.
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Now you have a likely suspect for who bunged your bung.
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Overtightening and gradually stretching threads to the point of failure often occurs over time and repeated over tightening.
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You keep saying dies but you do mention tapping the pan hole. A thread forming tap would be preferred over the thread cutting tap.
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Yes, you are correct. Iām getting confused in my old age.
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My uncle always said getting old aināt for sissies.
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You hear frequently about spark plugs that wont come out.
Not that frequent. Those are plugs that have been in the head for an extremely long time (100k+ miles - which could be over a decade for some people). Many plug manufacturers like NGK remedied that by coating the plug threads with anti-seize.
As a follow on, I heard about 30 years ago that steel spark plug threads seizing in aluminum heads was often due to the different coefficient of expansion causing the plugs. I had at least two plugs seize in the heads of a V6 I owned back then and paid a lot of attention to it.