Middle Iron Corrosion

[JustJeff]

I was doing final assembly, got to the middle iron and noticed corrosion. I have no clue when or how it got there. At first I thought it was damaged when I knocked the iron over and onto some tools while putting the front rotor in.

After closer inspection and even testing a bad iron by pushing it over onto the same tools. I found that it wasn't damaged when it fell over. The only thing I can think is that I sprayed all the parts off on Sunday. After sitting for almost 2 years they had gotten dusty, spider nests, etc.

I tried cleaning the surface with some paint thinner but it won't come off. I can feel the marks with my finger. Obviously I'm concerned how they will affect compression?







My thoughts are that they must be from hosing the parts off a couple days ago. I did not coat them with anything afterwards I was expecting to do the rebuild Sunday. It has to be recent, I can't believe that I'd miss something like that.

[NoDOHC]

The oil film should mostly fill that corrosion near the port, although it is a crying shame that you didn't get some WD40 or oil on the housing right away to prevent that from happening.

I would be most worried about the corrosion in the oil control ring region. It appears that you used some type of water-based solvent to clean the housings, as the corrosion seems to track a drip path.

Good center housings are about $50 on eBay typically. NA center housings are pretty common.

[RETed]

You can typically knock off this kinda of "surface rust" with some light oil and a fine grit sandpaper.
This should not affect compression in any way.
This is the good news.

The bad news is that Mazda gas-nitrides those surfaces for wear.
Rust will usually eat through this gas-nitride surface, causing accelerated wear on the housing.


-Ted

[To_Slow]

Wee here at ChipsMotorsports.com can surface grind and re gas nitrate the plate for you.

Pics with info http://rotarycarclub.com/rotary_foru...ead.php?t=3109

Pricing http://www.chipsmotorsports.com/serv...d-re-nitriding

Hope this helps.
Chip U

[JustJeff]

Originally Posted by NoDOHC

The oil film should mostly fill that corrosion near the port, although it is a crying shame that you didn't get some WD40 or oil on the housing right away to prevent that from happening.

I would be most worried about the corrosion in the oil control ring region. It appears that you used some type of water-based solvent to clean the housings, as the corrosion seems to track a drip path.

Good center housings are about $50 on eBay typically. NA center housings are pretty common.

Yeah it is a shame, I had a friend on his way to help with the assembly. I washed everything off thinking assembly was going to start within an hour or two. Friend gets a flat on his way, it's Sunday so he had trouble getting a replacement tire for a long drive after helping me out. I did give some thought to recoating the irons for overnight...but again thought the assembly was happening the next day. When another roadblock happened it didn't happen Monday, but thought it would happen Tuesday.....frustrating to say the least.

The only things I used to clean any of the engine parts was Simple Green, acetone, when I ran out of acetone i switched to paint thinner. I did spray them down with water Sunday.

Originally Posted by RETed

You can typically knock off this kinda of "surface rust" with some light oil and a fine grit sandpaper.
This should not affect compression in any way.
This is the good news.

The bad news is that Mazda gas-nitrides those surfaces for wear.
Rust will usually eat through this gas-nitride surface, causing accelerated wear on the housing.


-Ted

What kind of lifespan would you give the iron? I want to get many years out of this rebuild.

Originally Posted by To_Slow

Wee here at ChipsMotorsports.com can surface grind and re gas nitrate the plate for you.

Pics with info http://rotarycarclub.com/rotary_foru...ead.php?t=3109

Pricing http://www.chipsmotorsports.com/serv...d-re-nitriding

Hope this helps.
Chip U

I appreciate the offer, but I'd opt for replacing rather than lapping. Just wouldn't be cost effective. I don't want to do the whole engine. I'm not sure how doing one iron would effect things. It'd be more cost effective to find a low mile replacement.