Therx7ist

Hey, I've got cracks on front cover of the TII motor I'm tearing down. They seem to go through and they are all over the place. Is it toast? If so, are all S4 front covers the same? Turbo and N/A?

BlackTurbo2

I wouldn't try to fix it or re-use it... find another. Series 4 turbo and NA front covers are not the same.

apreludem

i think some minor cracks are normal in castings....best if you post pictures

BlackTurbo2

Minor cracks are not... stress cracks on the surface are, but not if they go through like he said. but ya, post pics if you can.

Therx7ist

yeah, they seem to go through. my other N/A cover does not have these cracks

BlackTurbo2

Just find a replacement, its not worth putting it back together to have a problem later. If your skeptical, replace it.

apreludem

if they go through then don't use them...if you post pics people can confirm this.

Therx7ist

pics

Wizz

Those "cracks" almost look like casting marks.

Therx7ist

some of the cracks appear to have a matching partner on the front side

The Spyder

iTrader: (8)

That looks normal......

scathcart

Normal. They all have them. Seriously, all of them. They're always most noticable on the inside of the cover. You can sand them out if you really want; they do not go all the way through.

Poor casting techniques.

Therx7ist

great, thanks for the answers. Glad I can use it

Therx7ist

what about this housing? What do you think


https://www.rx7club.com/2nd-generation-specific-1986-1992-17/should-i-looking-new-housing-464662/

fcfdfan

I'd replace it. Email the pic to Mazdatrix out here in Cali. I would trust their opinion.

Good luck.

homebrewer

Those are normal, I'd use the cover again. My cover looked just like that on my low mileage vert.

TonyD89

iTrader: (10)

I work in the mold-making industry and what you think are "cracks" in your front housing are really cracks in the die cast die. They do not affect the integrity of the part. So long as the part can be trimmed, machined, and work in the final assembly. Untill one of the afore mentioned criteria is comprimised, it will be run till pieces of the die begin to pop out, it cracks in half, or a crack makes its way to a cooling line in the die. At which point it may be repaired or replaced. It IS NOT A SIGN OF POOR CASTING TECHNIQUE and followed through-out the industry, wether foriegn or domestic. Period.

scathcart

Dye penetration testing for cracks in the front covers says you're wrong. The cracks are surface level cracks in the actual aluminum, which come from cooling cast aluminum too quickly. If the cracks existed in the mold, the cracks in the cast material would be external and be felt as ridges and not show up in dye-testing.

It IS from poor casting techniques.

TonyD89

iTrader: (10)

Most rotor housings(from mazda) have the same marks on the outside. Look at them! They are from cracks in the die.

scathcart

I have dye-penetrated tested the front covers. They ARE surface cracks. If the cracks were in the dye, there would be ridges, and would NOT show up in dye testing.
When you can say you have done the same testing, let me know.

TonyD89

iTrader: (10)

Man, I have looked at your pics over and over. I think you are obsessing over a non-issue. If you look at other die-cast parts on your car you will see the same stuff. Look at the tranny housing (if clean), accessery brackets, water pump. rotor housings. I just don't believe you have a problem.