mad dog mentioned hard starting problem....

just wondering, what are other common indications/obvious&subtle symptoms of broken or damaged apex seal?

thanks.

 

Hot damn man, already?

 

the car will not start. under normal operation the 13b wood last 150,000.miles. i had my 86 for 120,000+ miles and chage it for a twin turbo wich i had for 50,000+ before i sold it to move to tacoma washington went i going the service{us army 11b infantry) for six years, and my 8 is running fine after 30,000+.

 

haha well, i don't know if i'm even having such problem.

so before i jump to conclusions, i just want to make sure i may have a cracked seal.

i do have a very rough start even when the engine is fully warmed up, and when mad-dog mentioned that this can be a possible sign for a cracked seal, it got me a little worried. it does start, but it's not as crisp as it has been before. and yes, i have the new high-speed starter motor.

i must admit though, my last two tanks of gas only averaged about 130miles.

 

listen to the way it cranks over.

a good engine will giv eyou 6 pulses. ^^^^^^
one blown apex seal will kill 2 combustion chambers, and sound like ^^^-^-

if you want, i can have a look next time i'm down there. i've got a digital pressure sensor i'm converting into a datalogged compression tester.

 

When did the problem start?

 

i can't quite put a finger on it. my car was put thru probably more than 20 dyno runs over the weekend, interspersed by killing evo's and sti's, so everything has been a blur. the starting sound really started to bug me this morning. something just didn't sound right.

guitar, please let me know when you're in town next time. pulse checking sounds like just the thing i need. do i hear it while turning over the flywheel with a screw driver or with the starter motor w/ fuel supply cut? thanks for your help!

 

take out your spark plugs, cut the fuel and crank it with the key.

 

starter motor with the fuel cut.

gimme a few days to see if i can make the datalogger work and we cna get some good results. you've got my # anyway, give me a call on friday around noon or so to see if i'm down there.

what i've seen in a few renesis motors is the apex seal cracking in half right in the middle. other than a good compression test, this is VERY hard to diagnose, because it can still crank and run just fine--until it finally gives out.

 

Why not pull the plugs on one rotor, try to start, replace the plugs and repeat for the other rotor. You should be able to run the car on one rotor.

 

i wouldn't want to be spitting out gas on the side of the motor.

 

The best indication,other than a compression test,is the idle---if you have a slightly damaged apex seal,say a crack to 1/8 inch break,you get a rough loping idle,car will start and will run reasonably well(at least until more damage occurs).

 

cool thanks. i'm not in a big hurry. it still runs fine. i can wait until you can spare some time to look over my car. if seals are cracked, i suppose i'll just ship it to the east coast rather than driving it. i am planning on taking off in about 10 days by the way. i do plan to go to willowsprings raceway this wknd though!! if i'm gonna blow it, it must be at a track just like my last time w/ rx7.

 

the idle is good. it's smooth. no violent ups and downs. what kind of loping are we talking about? one up & one down in one second? or one steady up for 3 seconds & little down for another 3 seconds?

 

assuming you had the cash and the motor actually IS blown, i can have a motor rebuilt, ported, and installed in that thing in 10 days.

 

how much for the whole job? i would like to have 3mm apex seals as well.

 

hit me up on aim and we'll talk about it. fcrotorhead.

p.s. you don't need 3mm apex seals. they'll break if you detonate, too.

 

Yeah what do you call a rough idle. My car idles fine except every 10 seconds or so you get a little "miss" or lump in it, should I be worried? I would think it would be a continuous "miss" or lump if a seal was having troubles, right?

 

Before my Renesis failed completely, it idled OK, but stuttered a bit at low RPMs (below 3000), even when warmed up. I guess the cracked apex seal made it lose compression, which is more noticeable at low rpms/off boost.

 

Yes,continuous roughness or "miss".When my RX-8 motor broke a seal,the little piece which broke off hit the outside of the next apex seal groove and jammed that apex seal---so the rear rotor did not run at all. The picture shows all!Note the lack of carbon build up(12.5k miles)

 

^ i see that all too often. when you pop a seal in an older engine, theres a good chance it's gonna shoot out the exhaust port and you're out a set of seals. if a renni pops a seal, you're virtually guranteed you took out the rotor and housing. i've only seen one rotor and one housing (from different engines) that could have been reused after a seal went.

stickman, another good indicator is turbo spoolup. still spooling fast, or does it take longer to hit full boost now?

 

Wouldn't the motor be making funny noises if you have a problem like this also? I would imagine it would make a scraping sound or rattle.

 

not usually. most of the damabe occurs instantly. the loppy idle is the aftermath.

 

The guy who built my motor said the same thing--3mm seals are a waste of time unless you plan big boost(say 18-20psi or above).He also indicated that the wear rate on these seals is noticeably higher than 2mm seals.

 

boost pressure has no bearing on the necessary sizes of your seals. static compression does. while 2mm seals may last on a REW to 18-20psi, remember that they have lower compression. The static compression would be the same on a renesis at 16-18psi (everything else equal, which it is not, but you get the idea)