Some might know that i'm trying to learn everything i can about the rotary so that when i get mine i will hopefully know common problems.

Ok, lately i have seen alot of blown engines cuz of apex seals, and what not. Now i want to know what the apex seals are made of. Like are they lined with strong rubber or is the housing and apex seals made fo the same thing. Also is there any way to maintain the seals, or do you just have to wait until they blow to rebuild the engine. This may sound very newbish, but hey thats what i am.

 

No worries

Most apex seals (stock Mazda ones) are made of carbon-impregnated aluminium, IIRC. Some very expensive aftermarket ones are made of ceramics. Just think "piston rings".

The best way to maintain your apex seals is to

a) change your oil religiously at 3000 miles
b) frequently redline your car - you don't need to beat on it, but rotaries are made to be high-revving
c) use the right spark plugs
d) use good-quality, 87 octane gas in an N/A and 91 in a turbo

N/A rotaries are known to last 200,000+ miles, when cared for. Keep up with regular maintainance, and she'll treat you right.

Brandon

 

Yup, No7Yet nailed it! Just let me add that when you DO do those oil changes do NOT use any cheap *** junk like an "el cheapo" oil filter! Also in your ever changing climate, make sure you are using the right weight of oil for the season! All basic stuff I know, but still needs to be a mantra! Sure wish my TII would go that 200K+!

 

What was said about apex seals above was completely correct. A redline a day keeps the rebuild a day, or at least, so they say. That's a lot of rhyming really...

Anyway, rotaries are pretty reliable all things considered...Only doing stupid things will break them (too much boost, too much timing, etc). They are more fragile than a piston engine, but that's the price you pay for high specific output. Just care for your car, and it will look after you.

FWIW, I have just turbocharged my 247,000 KM NA engine, and have boosted it to 5 PSI...Seems to be holding up.

 

the apex seals are cast iron hardened with a laser.

mike

 

Uh, explain how you harden something with a laser.

I have always thought it was an electron beam, but what do I know...

 

Cast iron apex seals? Uh, I'm really not sure about that - I recall reading Koby-san talking once about being inspired by the graphite in pencils after having problems with scoring in rotor housings. IIRC, he tried impregnating aluminum (soft) with carbon (soft) and getting something much harder than he'd expected, but that was also semi-self-lubricating and didn't score the housings.

..but then agin, I could be wrong...

Brandon

 

Thats what I had read about the factory 2 piece apex seals myself.

Didn't look that way on the last 13B I rebuilt.

 

Trust me, they are cast steel. This is for all FC3S stock, 3-piece Mazda OEM apex seals.


-Ted