has anyone noticed these on rotor housings before? these are new ones still in wrapping. its looks to me that there were large defects/pits in the housing that have been patched with some kind of translucent-dark filler.

front


rear has 1 tiny patch. and what is the bagged rubber ring/plug thing? i don't remember seeing it during teardown.

 

They sold you that as new? Seems kinda shady to me.

The rubber thing is the drop-in insert for the oil metering plug hole I think.

 

yeah they were sold as new, which is complete bs. i received the boxes with the tape seal broken. so someone hand picked me defective housings maybe?

i did find a old post about having a engine fail soon after rebuilding because this defect. post #6 https://www.rx7club.com/showthread.p...+housing+epoxy

 

If you are planning to use the"the bagged rubber ring/plug thing?" you must buy the "new" style oil jets..

 

I found those rubber plugs as well in my package and figgered they were meant for the oil jets. Looking at my old housings I didn't find any so decided not to use them with my 93' oil jets

 

I've actually seen this a number of times in the past even on rotor housings purchased from Mazda. For some reason, I also found a large number of Mazda reman engines with this issue. While exposed porosity on machined castings is not uncommon, you'd think they'd find a better way to fill those pits. I agree, you have every right to demand an exchange, but if the situation were different and you were stuck with housings like that, the pits could be easily filled by an experienced welder. I've had great success salvaging such housings.

 

That's weird. I've got a set of brand new S5 na housings sitting at the house and they are pristine.

Looks like they jb welded (or something similar) some defects. Not a big deal if done right. JB welding is a common repair for rotor housing pits.

 

RHDjapan.com has perfectly good rotor housing direct from factory. 468.00 US. Had to ship for my rebuild. Running strong

 

i bought these from rhdjapan a few weeks ago. maybe i got the last ones i dont see them for sale anymore.

 

We at AZ Rotary Rockets buy direct from Mazda and they have sent us housings like this. So, yes these are factory, dont worry about it they will work fine...

 

thanks for the recommendation, how much did it cost for you to get similar defects patched?


pm'd you about a few details

 

its been over a week and no word from rhdjapan. in the past they were always fast to respond when i had questions. now a big problem comes up and they start acting guilty and ignore. i'll keep the thread updated if i hear back from them later like if they've overlooked my emails or are working on it w/o notifying me.

 

rhd contacted me today and said that mazda in japan says this patching is as good as housings without it.

i'm trying to get an exchange on them but i'll see how they respond.

 

Usually no more than $20. I have access to a milling machine, so I take the high spots down and finish the last .005" off with a fine file. Aluminum is easy to work with, so you can file the entire weld down with a file. Regarding the claim that having epoxy in those pits is as good as having no pits at all, I'd say that in the long run with the different expansion rates of epoxy vs. aluminum, it would come back to bite you in the ***. It may be fine for a while and the engines that I've seen this on didn't always have a coolant leak. I elected to fill the pits because I'm ****.

 

I understand your concern... but I would expect JB weld to outlast the iron of the thin-walled coolant seal channels by far.

Unless there are huge areas of jb welding done, expansion shouldn't be an issue. The smaller the amount, the smaller the change in size.

 

If they used aluminum-filled epoxy (which it seems to me they would do), the expansion coefficient of that would be very similar to plain aluminum. This is due to the fact that the modulus of epoxy is much lower than the modulus of aluminum. Therefore, since the epoxy just binds the aluminum particles together and to the interior of the hole, the aluminum would (mostly) control the expansion coefficient.

 

well seems like the word from mazda japan and amemiya is that i should use these housings and my engine will be fine. so i'm going to take my chances and watch for coolant issues, if it fails i'll get them aluminum welded. i have a 2nd car and im doing the engine work myself so it will just be a few more days of work if this is the case. im not too comfortable with having the welds done at the moment or my own ability to get the weld/surrounding area prepped to spec.. so it will be the back up plan.

thanks to rhd for getting back to me the past 2 days with their quick communication.

dave im not sure what the epoxy is made of but it doesn't look like aluminum to me, although im only saying this bc the stuff is brown and not shiny

 

they do not weld the inner surfaces because it makes those areas more prone to electrolysis, just a little tip.

 

with the rotor housing the cast gets air in it thus having holes in it, it seems mazda could have had a better vacuum casting system made for their engines. I dont think those will hurt the engine just sucks... the quality looks chinese.