Blown Apex Seal???
 

hello all, im already putting on my flamesuit for not searching hard enough (although i did do some searching). here's the issue:

last night i was on the interstate and had to accelarate quickly to change lanes since the one i was in was ending. as my rpm's climb i feel a sudden bog and a slight loss of power. later when i come to a stop light the idle is a little jumpy as the engine is shaking the car and shifter as it feels like its missing. i get home a do a small check in the dark, nothing obvious. i'm already hoping its not a apex seal. this morning a attempt to do a compression check, doesnt work out so good. seems like my new compression tester is broken or something as when i hold the release button down i get no bounces at all but when i dont hold it i get a weak bounce (30psi) then it bump up to like 70 psi and stays (the third is either equal to or less than 70 obviously) this is on the rear rotor. due to mothers day plans i didnt check the front yet. i took a video to show. hopefully you guys can tell if this is a blown apex or corner seal or something else that it could be. from what i have heard about the feeling/ sound of a blown seal, i think this might be it. as you can see, even the tail pipe shakes. also, if it is blown, what are the repercuptions of continuing to drive it? thanks in advance.

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Well, my engine sounds like yours. I dont know if mine have a bad cornel seal too but I checked my compression and I got 90 psi con each rotor. One question, when you test the compression do you hold the acelerator pedal to the floor? You need to have the throttle body butterflies opened. Also, try cleaning your spark plugs. Mines shakes a lot and loose power when one spark plug get fouled. . Just try to clean it.

The compression numbers don't sound promising, but you should definitely test it again with a better tester. If you lost an apex seal you should be seeing 2 rotor faces with the same compression value (usually low to nothing), but your numbers don't exactly show that. Another symptom of a blow seal is poor idle and hard starting, but it doesn't look like you're seeing that (other than the vibration).

Driving it with a bad apex seal isn't going to hurt anything, but a side seal may. Though you may find a bigger loss in power if the seal continues to deteriorate. Sometimes it's a progressive decline.

If it's a blown seal (it does sound like it very well may be) you should not continue to drive it if at all possible. Things can only get worse and wear will be greatly accelerated by having any blown/cracked seals (which reminds me, you may have just cracked one, and if so it could get worse fast). +1 for being fairly cautious about this. I suspect you've blown a side or corner seal, but it could be an apex seal or even something completely different like a bad vacuum leak. See if you can remove the valve in the plug end of your compression gauge, that way the bounces will show the actual compression (it will be fast, but should still be easy to read and you also will be able to see the compression on each face, not just the best one). If you see fairly even compression all around and they're all above 70psi I doubt you've blown a seal. If you see one or two faces with low, but not sub-20psi you may have a cracked seal. Blown or cracked though you're up for a rebuild immediately.

Also, is that a Camden supercharger?

At idle, do you pull less vacuum than you did before? If you notice a loss of power then something is probably gone. By the description you gave of the rear rotor compression test, it would seem that you have more than one seal gone on it (possibly cracked). When I warped RA seals, the car would start and run and drive in vacuum. In boost it would break up. The idle was choppy and the engine would shake at idle like yours.

Josh

its a paxton supercharger, check his sig. i really want one of those superchargers.

my bad on checking the sig.

The 'loss of power' statement seems too ambiguous. I felt a loss of power when I blew my turbo-mani gasket, and I only lost about 1psi average of intake pressure on WOT. Blowing a seal would also result in a loss of power, but it would be a huge difference.

yea when i blew my motor, my car wouldn't get out of its own shaddow under heavy accel. maybe its something else in his case.

Pull the plugs and listen to it crank:

http://www.aaroncake.net/rx-7/blown.htm

thanks for all the input from everyone, i really appreciate it. i didnt even think about the plugs being bad (they were just replaced less than 6 months ago) but then again, i am running pretty rich. in fact, i didnt even look at the one i pulled. i just assumed the worst so that i wont be dissapointed if i assume the best and it turns out that i need a rebuild. :) its been storming out here today tho, but i will check those plugs if it clears up and also try to borrow a better compression tester. thanks again for all the input, i'll update when i know more.

In regard to the plugs: No no, check aaroncake's link. You pull the plugs, leave them out as you crank and listen. If you have a blown apex seal then only 1 of the 3 chambers is sealed: i.e., 2 corners of a triangle completely surround only 1 side. In regard to the rest: good idea.

dont forget to disconnect your egi from your engine box thingy

Dont forget to unplug all spark plug wires, I dont think you want gas and flames shooting out those holes as you crank.

thats what disconnecting the egi does holmes

havent had a chance to check compression yet. it was storming yesterday and today i was working all day. again, i'll keep everyone updated. thanks again for all the support guys.

I checked at youtube and there are some RX7 videos with broken apex seals or cornel seals. You can heard the sound and compare to your car. After view a few of them I conclude that the sound of my car is related to the untune progamable computer indeed a blown corner seal.

Like Aarons listening method, you can use the "poor mans" compression test. Put your hand next to the empty plug hole. You can FEEL the 3 strong bursts of air each time it turns (per rotor). If it's blown, you will most likely find the rear rotor is not giving you 3 good bursts, maybe 2/3. Usually the rear rotor blows that's why I mentioned it. Your symptoms though sound like a dead motor. I remember my car shaking violently and having little power after I blew it. Sure as shit when I checked just by cranking I knew the rear rotor was gone.

Say it ain't so! If it is an apex or corner seal, at least now you can do a little porting while you're in there :D

when using a piston tester you do NOT hold the relase valve on the side open. what u have to do is remove the shrader valve in the portion u thread into the engine. Then u can see all the bounes.

ok guys, heres the deal: i did the :poor man's compression test and EVERYTHING WENT FINE. both rotors were giving 3 strong psssts of air in a nice, even sequence. this was very nice to see since it meant that a rebuild was not neccessary, but it also led me to believe that possibly the plugs were fouled really badly, and yes, they were. so i changed them. much to my dismay, this did not help either and the car is still the same as before. what do you guys think? off timing? not getting spark to one of the plugs (bad wires or coil pack?) or some other kind of electrical prob. all info is appreciated. o, and introvert: i know it sucks, but i was also looking at that as the silver lining too!

Do a real compression test please. Too many unknowns right now, everyone would just be guessing.

Do a spark test first. This will let you know if the coils and the spark plug cables are in good working condition.

i plan on borrowing a timing light tommorow to test for spark at all plugs. i will let everyone know tommorow

got the timing light and was gonna do a compression test but some stuff came up and by the time i was able to touch the seven it was raining and dark.....will update tommorow after work.

you need to do a compression test, with the shrader valve in the end that u thread into the engine removed... and then u dont touch the side valve. then u can watch all the bounces

kind of sounds like you might have chipped one. i broke off a corner and was only making ~60psi on that rotor.

Well my engine sound like that on the video. I taked the compression today and I get 90 psi on the rotors. I also think that I have one bad spark plug. I feel the engine is not pulling very strong and I have fouling problems since that (a lot of black smoke and is not idle very well). I cleaned the spark plugs and the same problems still there. I will try to buy new spark plugs today to know if the problem persist.

With the compression gauge I removed the screader valve at the hose end were thread on the spark plug hole. The I marked with masking tape the 90 psi number on the gauge face. Then I wire the gauge to the oil fill tube to see the gauge from inside the vehicle. Pressing the acelerator pedal to the floor and reading the bouncing needle. 90 psi on all the faces of the rotors.

well good news and bad news. good news is i dont need a rebuild! removed shrader vavle and did compression test on both rotors today and got 90+psi on all six faces. also checked for spark and am getting it to all for plugs. bad news is now im back at square one. i dont think its out of time, i believe its an electrical issue. i.e. tps, bad ground, etc. any ideas on where to go from here?

Sounds like my issue http://www.youtube.com/watch?v=_qRhmeqE-hM

I installed new spark plugs and the problems continue. My engine is sounds like the one on the videos. Maybe the responsable of that is something electrical.

For the ground problems is easy to test. You need a voltmeter. Put the one terminal on the positive battery post and with the other terminal check for voltaje between the battery post. Record that voltage. Then with that terminal test the voltage in the chassis, intake manifold, engine block, transmission bellhousing, ECU ground cable. You need to have a minimun of .5 volts between all that parts. If more you have ground problems. Just install new grounds cables for that parts to resolve the problems.

I will try to check my spark plugs cables and coils in the night without light to see if there is some spark jumping around to discard a damage part.

for the TPS and other sensores, go to the workshop manualas that you can download from the internet and find the title with the sensor testing section.

good to hear you dont need a rebuild, and wingsofwars motor does sound like it only his has some random clicking noise x_x

haha, i had a friend over the other day running tests on my car with me and one of his (aka NOT mine) friends who is supposedly a car guy dropped by. the first thing he told me was, "hold on man, i that sounds like rod knock!" talking about my pump for the s/c fluid. me and my firend look at him funny and i was like, its a rotary, there no push rods.... then he says, "o so then is it DOHC or SOHC?" we loked at him funny again and my friend then proceeded to explain to him how a rotary works (and hes a supra owner!). some car guy...your video just reminded me of that.

anyhow, i heard somewhere on this forum that an altenator that has too much load than it can handle on it (i.e. lots of electronics) may cause a problem similar to this. im not sure if that true or not. if it is, would it affect me since the only non-stock electronics i have are 2 gauges and the pump i talked about earlier. still, besides the rough idle i dont see any other apparent problems that might be connected to the altenator (plus the alt. is less than 6 months old). i'm gonna test the tps next and i also wanna constuct one of the home made code checkers for s4's to see if it throws any codes. in the mean time, if anyone has any other info/suggestions, dont be shy, please chime in.

I dont know what your problem could be but I can say with 100% certainty that its not a rod knock...LOL

:rolleyes: rod knock? Yeah, that frigging pump is loud, though! Every time I switch on the ignition, I get "What's that noise? Something wrong with your car?"

you know to be honest, i had a rotary with a spun rotor bearing, and it did make a sound allmost resembling a rod knock at around 3K sometimes , the bearing was so bad the rotor was wobbling and hitting the irons., and it smashed the side and corner seals in and lost compression on that rotor

iv also heard that same knock sound from a spun rotor bearing. Its really loud, probably more distinct than the sound that rod knock makes.

lol at dohc sohc

no vtec no engine!

nunchuckgun, i kno that this is off topic, but where do people get those things like the one you have in your sig? just curious

SHIT.....i definately have a blown apex seal......the test i talked about before, i didnt actually look at the tester. i was cranking while a friend watched. he told me it was 90 to 95 psi on all the rotor faces, and i was easy to believe him since my "poor man's test" gave good results so i didnt bother doin another while i watched (it was dark out and we were rushing, only really doin this as a double check since the "poor man's" went good. but he definately must have been mistaken. i got my fiancee to crank the car while i watched the gauge today just for shits and giggles since i was already working on the car doin tps and such. the are definately 2 bounces at about 25 psi and one at 90....so i guess that means the motor is done for now.....and im sad as shit, but at least now i have an excuse to port it! thanks everyone for all the info that was posted in this thread. i really appreciate it all.

Man that sucks, but good luck with the rebuild. Heres to reusable housings! Cheers.

that's real bad. But, time to grow the engine from a kid to a man.

You make me sad, now i have the urg to do another compression test just to make sure.

might be a good idea. i was all but convinced my tps needed adjustment or i had abad body ground. after checking both of those avenues and there was no prblem with either, i decided that i might as well do one more check while i was under the hood anyways....and the rest is history...