1990 S5T2 Compression
 

I'm sure some of you guys will remember the problems we have had with our S5T2 rebuild but I'll give a brief update.
This T2 was rebuilt with all new seals and gaskets. The engine started right up within 5 seconds and ran good for 35 minutes and then just died. We did a compression check shortly after it died and I was told the compression looked good. But, several guys said we should re-check the compression, so I finally did.
The first video is the front rotor and the second is the rear.
Let me know what you think of the compression.

Bite the bullet and take it back out, those are by no means "even" bounces, it doesn't even sound right rolling over.

My guess is a corner seal fell out since you have 2 lows and 1 high

Odd that both rotors are pratically pushing the EXACT same amount of compression, but weird things can happen

My vote is yank/tear it back apart

Yep compression is no good. Your getting one strong pulse and two weak pulses on each rotor. Even if you get it to run again i highly doubt you will build up compression. If i recall correctly a stuck side seal will show bad compression on two faces. Sorry for your loss.

How could both rotors fail in 35 minutes at idle? Any ideas?

If the engine is built wrong it wont take long for something internal to fail. I suspect the side seals weren't clearanced properly but really you wont know until its torn down.

I suggest YOU do the work or a well known rotary shop from now on. I checked out your old thread yesterday and suspected a compression issues from the start. Relying on others that said compression is good made it take forever to find the issue.

Agree completely.

More specifically, sounds like when the engine got fully warmed up, tight clearances became none or interference fits. Easy to do if you're just starting out on rotaries.

Could be as simple as a cracked apex seal, but hoping it's nothing too bad, and that it didn't mess up the rotor or any housings.

Let us know what you find out. It may help others out.

K, second time I can't edit and others have also said the edit button is missing. What gives?

Anyway, kinda related to the subject of assembling a rotary: Watch out for little details like putting the coolant seals the right way (the inner one has a particular way, incl. the location of the seam), apex seals go with the triangle piece (those that have it) towards the rear, oil control seal springs also go in a particular way in terms of rotation AND with the square end against the seal...the list goes on. Also front cover O-ring with/without washer, etc. Clearance checks (Felix mentioned) are crucial. Such as side seal to corner seal, apex seal vs. housing width, etc...

Several people joined in rebuilding it this last time, my daughter, her BF and me. But this wasn't our first rotary build. I can't remember who checked the side seals but I know they could not have been bad on both rotors.
I should have checked the compression myself, a long time ago, that's for sure.

Maybe something happened to the center iron. I suppose that would cause bad compression in both rotors at almost the same time.

Whenever we get a chance to pull the engine, I'll let you guys know what we found.

After talking to my daughter and her bf, I found out that the engine actually died in two steps.
The first was after it had run really good for 35 minutes. After it shut down the only way to keep it running was to tap the gas pedal constantly and disconnecting the TPS helped a little. So, that was probably loss of compression on one rotor.
After repeatedly trying to get it running for several days it just died and refused to re-start. That was probably loss of compression on the second rotor.

thanks for the input guys

The TPS being unplugged shouldn't of killed it, since you said you had to keep it alive after is was running for awhile tells me the engine let go before you had to unplug the tps and feather the throttle

The gage shows two low pulses and one high pulse indicating a bad apex or corner seal. (One low and two high indicates a bad side seal.) Does seem odd that both rotors show a similar failure. Really hate to say it after all you've been through, but the only way to figure out what's happening is to remove the engine (again), disassemble, and see what you find.