Ok, so engine ran fine..... at one point i picked up vibration in the shifter. I switched off and got her towed to my garage.

I have a large street port on, and on the mazda pressure tester for the rear rotor i got:

74
74
000 rpm999

rebuilt has just 80km, 3mm seals etc.

what your opinions?

 

If one of your side seals went it would pretty well destroy your entire housing, I doubt it was that. Seems like since you've got 2 rotor faces with like compression numbers and 1 with nothing, one of your apex seals is damaged. So you just felt vibrations and shut the car off, and now? Does it still start, idle?

 

yep, she starts and idles fine, just a little stutter with acc.

if its an apex seal, then two chambers will be affected not just one.

numerous tests indicated similar results.74/74/00

so i gather it might be a stuck side seal. I was having some issues with severe rich engine, and i was under the impression that there might be some bad carbon build up that caused the seal to stick.

this occoured at about 2500rpm in slow traffic in relatively low gear. 2nd if i recall.

any hint on how to test or free a stuck side seal... apart from opening up the engine?

 

Actually it could very well be a pinched side seal. Try reving your engine to about 8500rpms, sometimes it will go back in place.

 

sounds like a bearing fail, try draining your oil and look for brass cooper.

 

i think even a stuck side seal would give a bit of compression unless:

were you revving it up past 8k?

it might be possible that the rotor contacted the side housing enough to "weld" or pinch the side seal in place. i've seen it happen, but usually not just on one seal.

oh well, tear it down and let's have a look.

 

Hi George, nice to speak to a fellow Maltese, I doubt you could carbonize an engine in 80Km bad enough to stick a side seal, during rebuild did you clearence the side seals from the corner seals within Mazda's tolerences.

 

well here goes:

I never reved the engine past 5000rpm due to break in.
well, to fail a bearing you need to run without oil no? i cant see the connection between compression and main bearing though.
well what could cause a seal to pinch at less the 7 psi and less then 4000rpm?
clearances where as per mazda tolerances. new three rotor main bearings, solid corner seals and 3mm world solution seals. for the first 80 km i had no issues with the engine other then it was impossible to start hot....

Hey nice to meet a maltese guy on here too.... about time

Thanks guys.

ernie, so reving it up to 8500 and use injector cleaner in the intake could help? i mean i swa it stange for the engine to be fine at first then develop a vibration under minimal driving, and the compression tester reading 000....

confusing

Thanks

George

 

kinda sounds like that side seal might have been a bit too tight.

 

Yes, same thing happened to me one time at the track. It will lope at idle like you motor is blown, but I revved the **** out of it (nothing to loose) and it got unstuck and was fine thereafter.

 

hmmm..... so i rev it up and rip the **** out of it...usnig some kind of solvent in the intake?

ps? under load or just free reving?

Thanks

 

weird thing though, she starts and idles normaly... thats what beats me

 

If you were running extremely rich, I've read about having too much fuel in the chamber causing it to "dry out" in a sense, and making the internal parts far less lubricated. Ernie does have a point though, worse comes to worse, what do you have to lose by revving it up and praying ; )

 

if it happens to be what i said before, the rotor could bounce around and kill the iron, then he'd have more parts to replace. i say crack it open and be on the safe side.

it's a new motor, so most of the parts should be reusable.

 

Get a gallon of distilled water, warm up the engine.

Put a tube onto one of the nipples that you use for the boost guage, rev the engine to about 4500 and put the other end of the tube into the water. Let the engine suck in the water and just make sure that you keep the engine revving so it doesn't die.

Run the engine for a few minutes afterwards to let it cool down.

That should help remove any carbon and help loosen a stuck side seal if that's what it is.

Attila

 

Was the compression test performed on a warm or cold engine. If losing comp only on a warm engine sounds like a tolerance issue.

 

^ good, but it takes 10-15 minutes, and bump up the timing to get the egt's hot.

 

thanks guys.... i willlt try this out. I am waiting for my to4r. I will try and get my manifold, block off the turbo flange, and run the engine wastegate runners into a bucket of water...(would scare the crap out of the people on top of my garage!!!)

i will try the solutions.......however , i may be reluctant to damage the iron, i just had them dowel pinned, and that the last thing i feel like doing.... muckin up the side iron.

thanks guys..... will keep you posted.

atihun, i will try the water thing too!!! can it cause any damage to any vitan o rings internally? i meant steam and vitan if i recall well are not really competable, vitan swells up in contact with water....

george

 

ps, i just did the comp on a cold engine. i wasnt after figures but parity of figures. when i tried testing the engine warm before pulling apart turboes and all, front was like 89 89 88. but i was getting no reading whatso ever on the rear.

prolly the tester was playing up on me. anyways i just tested yesterday while awaiting my turbo from the us. i just wanted to be a 100% sure. unluckily though i got those readings!

sure sucks!!!

thanks again

george