Throttle body stress cracks, anyone seen this before?
 

Not too big a deal or cause for concern, but kind of interesting...

http://www.anodized.com/~clayne/fd3s/tbstress.01.jpg


http://www.anodized.com/~clayne/fd3s/tbstress.02.jpg

I would say that is in the casting from the get go.

Those are not cracks in the casting, that is just dirt/carbon from the intake air. It is possible that there are very small ridges in the locations where the dirt/carbon collects.

Typically when you see "cracks" on aluminum die cast parts they are actually cracks in the molds that appear to be cracks in the casting. The mold is made from steel, it sees 1000's of heat cycles and quickly starts to crack. The cracks in the mold usually don't effect quality.

Nope, they're definitely cracks caused by clayne's leadfoot. He's just afraid to show pics of his throttle cable collection :)

Yep. I also did some throttle body fixes (inspired by RETed) that I'll be putting up in a little bit.

Also, you guys are saying I shouldn't throw the throttle body around the garage right? ;)

Jeff,

Are you saying what appear to be cracks are actually ridges mirrored by the original steel casting cracks and carbon has collected against them? Or are you saying that it is merely carbon that has collected on the housing, regardless of if the housing was smooth or not?

I wouldn't think the latter because the pattern highly resembles fracturing - which dirt/carbon would not settle in (provided the surface was completely smooth and previously uncracked).


Some more pictures:

No cracks here:


http://www.anodized.com/~clayne/fd3s/tbstress.03.jpg


Nice how the double throttle plate structure inside the manifold doesn't match up (gap-wise) but that's easily fixable.


http://www.anodized.com/~clayne/fd3s/tbstress.04.jpg

Also, anyone happen to know what the greyish iron-paste looking material that surrounds the edges of the throttle-plates is?

It seems applied on there and not just dirt/oil/carbon build up. Some degreaser I was using dripped down and took a small portion off, so we know it's on top of the plate.

I'd imagine it's some sort of graphite or moly compound coating to keep the throttle plates from wearing into the throttle body.

Did you try cleaning the throttle body like the second picture? I bet cleaning it would remove the "cracks".

-Jeff
93' R1

Yes. I cleaned off that part first just to make sure.