Specs,

1991 13bt
Hsg: no imprefections, no flaking, gouges, or damage
rotors new x 2 rebalanced w/ecentric and counter weights etc.
all new seals and springs
small side port
60-1 with all supporting mods

engine fired up well and compression was measured at 40 minutes, and then at 200, 500, 1000 and finally 1800 km's

compression rose steadily until last measured compression was approx 120~130 on all faces (rotary diagnostics compression tester)

2 weeks after last compression check took car to get smogged on the way there power fell off, and limped home. Checked compression and front rotor was down to 60 psi on two faces

pulled the engine this weekend (following earthquake) and after getting the engine on a stand looked through the exhaust ports to see all apex seals in place and apparantly healthy, pushed each one felt good spring tension, and all returned to position.

so the question is have any of you ever had a side seal or corner seal jam in place on a freash rebuild?

thinking maybe one of my corner seals jammed in the bore or something. tried doing a water injection to clear carbon prior to pulling motor, and it made it worse, though I did not measure it this time.

any thoughts?

kenn

BTW this is like my 20+ time rebuilding a rotary over a 25 year span and this is a first for me.....kinda stumped. I have had apex seals snap, on fresh rebuilds, but it was generally the tuning that caused it while breaking in

 

Stuck side seal perhaps, a bad apex would show compression loss on 2 faces. A stuck side seal would kill compression on one face and may impact the other two.

 

did you clearance each side seal?

 

did you cut an early open extend port?
my initial thought however is light det has taken a corner seal

 

i would say you got a split/cracked apex seal, pulling it appart is faster then our speculations

 

That too, possibly

 

always, though I tend to run my clearances on the tighter side for a turbo motor, not quite Judge Ito NA tight, but deff tighter than mazdas specs.

same open timing, slightly extended on closing

I will be pulling it apart this weekend barring earthquakes, tsunami's, nuclear mealtdowns and Godzilla

just first time for this in all the rebuilds I have done. the split cracked corner seal sounds interesting though as it lost compression on two faces .

kenn

 

After reading this thread it describes exactly what happened to me as well. Perfect running motor, out for a drive, give it a 12psi kick ( nothing out of ordinary) and at a stop light it starts sputtering and struggling to idle. Pulled plugs and on the rear rotor i get 1 good and 2 weak pulses. Pulled motor out and checked apexes and all 6 are solid (RA super seals). Id hate to open this and find nothing but apparently something's up.....anyone got ideas?

 

I wouldn't pay too much mind to the poor man's compression test yet. Go ahead and do a pressure test for boost/vacuum leaks. See if something is up with the plumbing. I recently had a bizarre issue with my throttlebody, which was not sealing properly causing intermittent vacuum leaks + sputtering/stalling. I swapped throttlebodies and it was all good.

 

nah... all tests done and its low....
listen closely...this is the rear rotor.