J Schmidt

Yesterday while changing my S2000 fluids I noticed what looks like a myriad of fractures on my oil pan and a few on my tranny case. I am not sure if they have been there all along or if they recently formed. I am hoping they are from the casting process and not really fractures. Anyone seen these before?
EDIT OK OK so through an internet search I found that it is indeed from casting but still would like something a little more authoritative than an internet search.

Billman250

Completely normal.

windhund116

Aluminum surface cracking. Prolly occurred during casting process. Not sure how to fix this. Nor how much of an issue these cracks will become, as the car ages.

Sorry, for the incomplete answer.

Habitforming

I don't think it's right to call them cracks. They are protrusions, not voids, in the surface. The sand mold used to cast it is what had the cracks. Probably those lines become more concerning over time as the pan gets more dirty and they stand out more.

I light sanding on a couple of them will allay your fears, as it will be smooth metal underneath. Not cracks!

J Schmidt

Thanks all. Can't get more authoritative than BILLMAN.

slalom44

Almost right. The oil pan and many other castings on our car are Die Castings. Instead of a mold made of sand, the molten aluminum is injected into the cavity of a water cooled steel die. This results in a dimensionally accurate net shape part with a smooth finish that requires little machining before assembly. Over time, thermal fatigue causes surface cracks on the die face. The cast part gets the mirror image of these cracks. They're just cosmetic and don't affect the part's function. Since these dies are very expensive to replace, the manufacturer will continue to make parts until the water-cooled die starts leaking or Honda considers them unacceptable. The alternative would be a more expensive part, thus a higher priced car. All cars have this issue, not just the S2000.

lqh2552

Very nice explanation ; I used to work at a Tier 1 aluminum die cast supplier, with Honda being the highest volume OEM we dealt with. I believe we called these surface cracks on the die "heat-checking". It amazed me what kind of parts Honda accepted, especially as the dies aged with time and shots. But, again, they are only superficial and won't cause any leaks. If anything, they are actually "positive" material added onto the oil pan, as the molten aluminum fills in the "negative" cracks in the steel die. And as one of the above posters mentioned, you can sand them away to make the oil pan surface smooth if you really cared to.

jkelley

I SMELL WEIGHT REDUCTION MOD, the start of your build thread?

Adrenalize

Agreed.

I remember the first time I noticed these 'cracks' too, I was scared lol.