WackyRotary

Hey all those who rebuild engines with budget in mind. I acquired a 12a car and disassembled it-a engine that had been overheated and a inner water seal had gone out on it. The rotor housing had a clapsed portion by a spark plug-so I know it was plenty hot. So I declared these rotor housings junk-even though they had no crom flaking-warped and no good by the spark plug of one. The engine had 80,000miles on it, and the engine had sat for 2-3years with some oil/water in the chambers. So it was locked tight due to rust/corrosion of the rotors, didn't even bother to try to turn it for fun when taking it out. I took out and took the apex seals+springs and they had plenty of rotor rust crude that came off with a bit of scrubbing. There overall height and thickness are well with in spec. The springs are also in good shape.

Would it be a bad idea to use these in another engine? I have all the rotor housings, other seals, endplates I need to build one with just a gasket set. The main reason I'm worried is that I think these apex seals may have hidden damage from overheating or rusted and material and fail quickly. Has anyone ever taken apex seals from a overheated engine/or engine that sat a long time with water in the chambers and had good success with extracted apex seals from them put into another engine?

Elysian

i personally wouldn't use them... whether u can or not is a different question, which i don't think i'm much qualified to answer heh

Jeff20B

iTrader: (13)

You could reuse them. The break-in time will be a little longer, but that's fine if you're ok with it.

nimrodTT

If they had surface rust I wouldn't reuse them unless you don't have another option. When Mazda makes the seals, the steel is heat-treated, so an overheated motor should not affect them much more than normal use.

What's the "clasped portion by the spark plug" you are talking about?

Jeff20B

iTrader: (13)

He's talking about rotor housing crush which occurs at the spark plugs which is the hottest area of the rotor housings.

I think stock apex seals are iron instead of steel.

WackyRotary

That is exactly correct Jeff. I've acquired two engine with overheated issues. Both had clapsed portion by the sparkplugs. It sucks someone didn't know how to read a low coolant indicator or temp gauge on their car. I know there are plenty of rotary owners that don't know how critical it is to keep a rotary full of coolant and in the correct temp range.

Another stupid question: I haven't checked the endplates or center or front plates. Wondering if they are warped. Haven't checked, but if the rust of the rotors is cleaned off, how warped they are or if they were lapped, would they be good then? I know aluminum can't take half as much heat then the cast iron portions can. Just curious...

Jeff20B

iTrader: (13)

If the side plates are waterdamaged, chances are good that they're bad. Scrape the rust off of the bottom of the plates where the water was sitting. If the metal looks discolored, see if you can dig into it with a fingernail or the edge of the razorblade. If you can, they're dead. The stock nitrided surface is hard enough to resist light scratching from a razor blade. Just test several areas of the wear surface to get a feel for it.

I'f reused the sideplates from an overheated recently rebuilt engine. I swapped the rotor housings and got another gasket set. Cheap and easy to rebuild since the rotors themselves and the oil system were fine.

DAVID GRIMES

clapsed = collapsed

WackyRotary

"clapsed = collapsed"

nimrodTT

They are a heat-treated steel alloy.

If the surface is blued or badly pitted, get some other plates. FYI: The stock nitride coating does not live long inside a motor, if you see even the slightest signs of wear on the side plates, that coating is long gone. It has long been my understanding that mazda first introduced the coating to prevent corrosion of the housings; not as a method of wear protection.