step 2) should be trailing

compression for 93s 85psi and 21 psi delta

pages c9 and c10 of the service manual

 

Thanks Books.

Where are you located in St. Louis?


* Yes, I'm still fishing for local help

 

A motor with ATF on the seals is going to read wrong...so for now, your exact psi number don't mean much.

If you get the 3 solid hits per face, then once you get it running...take it to Mazda for an accurate test to see how good your compression really is.

 

Do you think it still has ATF in the chambers? It has cranked quite a bit since I put it in..

 

It will still have ATF in the small cracks in the seals....and probably a thin layer around the housings....nothing has gotten hot inside to burn it out...you have simply wiped it around with your apex seals and little by little flung it out the exhaust. It would be like cleaning an oil mess on your floor with a squeege.

 

Makes sense.

 

I agree, whether the compression reading is accurate or not is not the point. The idea behind the compression test is to verify that there are no stuck seals or broken apex seals.

 

Any news?

 

I won't be able to mess with it until Sunday..

I'll let you know..

 

Stonewall7,

I sent you a pm.

 

Books came out this morning (Thanks again by the way) and we did a compression test on the motor. It has about 30PSI on the front rotor and 0-5PSI on the rear. How can the compression be so low on the rear?

- Neil

 

You have a stuck seal, blown seal, etc..

Did you have 3 even hits front and rear? 30-30-30 5-5-5 ? or what? Generally you can start a motor on one rotor...it just won't idle too well or run worth a damn. But they will start. But 30 is really low as well as the 0-5 on the rear...so it doesn't suprise me that it won't start.

 

Books was watching the gauge while I cranked it but I think is was so low that we had to rely on the valve on the compression gauge to hold pressure so we could read it. Even if a seal was blown or stuck on the rear rotor wouldn't the other face read higher then 5 PSI?

 

What are your plans for the car now? Rebuild? LS1? It sounds like you basically blew out your rear rotor...not 1 seal, but 3. Did you flat foot the gas? Did you make sure and have your trailing plugs in the car and tight? Without seeing what you did, I can't be sure as to why you have the readings you do...I am more than willing to look at it myself for you. It depends on your plans...and your budget though. If you plan for the worse, what are you plans, if you can get it running, what are your plans? Sorry to hear you bought a car that is potentially popped.

 

I believe there were 3 pulses of about 30 psi on the number one rotor. On the 2nd rotor, I can’t say with certainty that I saw any pulses. If it had any compression at all, it was close to zero. Perhaps the seals are stuck on the 2nd rotor and soaking them for few days may help or maybe pieces from a blown apex seal broke one of the 2 remaining seals causing 0 psi all the way around. I’m willing to test it again, if you want.

 

I knew the motor would have a limited life but it only had 60-70K miles on it. I never got a chance to drive the car since it came off the trailer like this. I know it drove on to the trailer under it's own power. The driver confirmed it. It is possible that he did something to the car but he was like 60 years old so I don't think it was on purpose. I am leaning towards going the LS1 route. I would just need to sell the rotary, 5spd, and other parts to fund the conversion.

Do you test compression from the leading or trailing plug? I think we were using the trailing.

 

Sucks to see another lost soul...

 

It doesn't matter if you use the leading or trailing for compression testing this way....you are not looking for numbers, just pulses(hits). The main thing is just making sure that which ever plug you are not using, trailing or leading, is tight in the housing. If it is loose or out, obviously you will show a 0 compression number because the air is escaping through the other spark plug hole on that housing.

60-70k is about the, get ready for a rebuild, mileage. It really depends on how well taken care of the car was. I just wasn't sure your plan since you did decide to buy a rotary car that supposedly ran, and I assume you paid more for it as opposed to a roller....so perhaps you were going to try the rotary situation out for a while, even with the bad luck you have had already.

If you need anything, don't hesitate to ask....and good luck with your car which ever decision you decide to go with.

 

Well I talked the previous owner down to a price that was close to a roller. I figured I would drive the rotary around for a while and then decide what I wanted to do from there. Looks like the decision has been made for me. Do you know anyone that is looking for an engine to rebuild or for parts? This one is pretty stock. I will also have the 5spd plus any driveline parts..

 

Not really...blown motors, used trannies, and all that are generally not very desirable. Does it have the dual oil coolers? Those will sell pretty good for you. The tranny, assuming it has no grinds will fetch a couple hundred. The driveshaft and powerplant frame may get $50 each. The blown motor will get a couple hundred as long as the housings aren't ruined. The wiring harness in complete and good condition will get you a couple hundred....if it is damaged, missing connectors, or extremely brittle, don't expect too much. You have probably $1000 or so in parts to sell assuming you have no aftermarket.