im just trying to learn as much as i can, i just enjoy doing this. ive rebuilt a rotary twice now, and i understand how they work pretty well i think. but what i wanna know are why do apex seals die? i know one obvious one, detenation. its like a small bomb going off in the combustion chamber, so it breaks them. but i know that isnt the only thing that kill seals. what else would do it?

 

I'll add one. Carbon building up behind the apex seal, preventing its return to the seated position, so it remains stuck out, and shatters/digs into the housing.

 

see, thanks... thats exactly what i wanted to know... if i can find out WHY seals go bad, then i can better prevent them from doing so. cool, anyone else?

 

Friction and heat are all that i can think of, but that's a given.

 

stuff in your intake. Like small pebbles or who knows what. I've even seen pictures of people who dropped screws into their intakes. Well that doesn't blow the apexs only, but scars your housings pretty deep and basically scar and dent everything
Also some apex seals can't take high boost.
Carbon for example are just for N/A's
And sometimes blown apex seals can chew up your turbo as well.

 

Sounds like my problem.

 

what about oil starvation. if the lines from the omp go south then there is no oil to protect them. premix and omp makes apex seals

 

Ill go a little more in depth on this. Without oil, the apes seals simply have too much friction. They build up heat, which weakens them until the extra stress on the seal from no lubrication is enough to cause it to crack or shatter.


Heres one noone mentioned. Its not common on non-race engines unless they get over revved though. The ecc shaft flexes at high rpm(10K+), which causes the rotors to sometimes hit the side housing. If it hits the side housing hard enough for the side of the apex seal to touch the housing, the seal shatters. Like I said, street engines usually dont get high enough rpm's to cause this to happen unless they are over-revved.

 

Fuel starvation is probably the #1 cause of seal death. The higher the revs the more fuel it needs.

 

i was wondering why the rear seal is usually the one that goes out first
an engine builder told me that he thought it was from the balance of the engine that caused the rear seal to usually die first

 

because it gets lets airflow to help cool it down the rear rotor runs at a hotter temp than the front one, just like on a front wheel drive car with a V6 motor in it, the bank nearest the firewall runs ALOT hotter than the front

 

Do apex seals acually Scrape down and get smaller after thousands of miles?

Perhaps so many miles on em they get so small they pop out quite easily of the rotor and scrape the crizap out of everything...

Question abour premix... basically you got rid of the OMP and you put oil into your gas everytime you fill up ?

how much oil do you put in with how much gas? OR

am I a moron? Thanks....

 

well i left the omp running. i read some where that the oil injectors are in locations where the oil is needed most. makes sense so i left it.

i put 8 ounces to every fill up. i use vavoline (t3 wc certified) or what ever its called. i buy it from discount auto parts.

they wear out eventually, but with premix and omp running the life of the apex seal should be alot longer. granted your engine is tuned right!

 

Yes, apex seals do noticably wear. On the n/a engine I pulled out of my 90, the engine had 150K, and the seals were worn down to about 60% of the height of new seals.

I use premix too, but without an OMP. I put 1 oz per gallon of gas. And you do have to put the premix in everytine you get gas.