engine damage - why?
 

So for the last couple of days, I thought I had flooding problems. I started the car up after 3 years after doing a whole bunch of mods to the car. The only thing that wasn't modified was the engine. It started on the first crank surprisingly. I was using a base map that another member made and modified it to have conservative timing and run really rich (11 afr). Boost was set to 9psi on the gt35r. Came the next day to start it and it wouldn't start. I thought I flooded it. After struggling to start it for a while, it finally started with some atf. Car sounded like it was running on one rotor. I pulse reved it to "free up" the apex seals. The car sounded much better. Took it for its first spin around the block to check out afr's and detect knock, and give it 70% throttle in first gear while watching the afrs and listening for knock. Everything was normal, but as soon as I slowed down, it sounded like it was running on 1 rotor and then it died. Pushed it back home and tried to start it at home. No go. Did a compression test, front rotor was missing two compression pulses. Time to take apart the engine.



This is what I discovered:
rear rotor housing damage: (can't be reused)
http://i130.photobucket.com/albums/p...earhousing.jpg

rear rotor has a very tiny indentation near the bowl, everything else is mint. will probably sell this.

the intermediate, rear, front housing, and eccentric shaft have pretty much no wear. will probably sell these.

front rotor housing damage: (can't be reused)
http://i130.photobucket.com/albums/p...onthousing.jpg

front rotor damage: (can't be reused)
http://i130.photobucket.com/albums/p...frontrotor.jpg



during disassembly, i found out that the primary air bleed sockets, which I bought brand new and put in, were broken.
http://i130.photobucket.com/albums/p...eedsockets.jpg


do you guys think that the airbleed sockets could have done this much damage?


on the bright side, the gt35r turbine is fine.

Did you take the housing off the turbo to inspect it? Fin damage occurs at the tips, hidden by the housing.

http://www.banzai-racing.com/how_to/damaged_turbo1.jpg

you were right. there is a bit of damage to the fins. can i just replace the compressor wheel and get it rebalanced? it's a gt35r. sucks that the turbo only had 1km on it.

Yes. Those plastic pieces can cause major damage. They usually get stuck in places causing things to break. It is very easy to break off pieces of the old ones and have them fall inside.

I assume you mean turbine wheel? Garrett doesnt sell replacement parts for the gt series, but if the compressor wheel and chra are in good condition you can use Garretts exchange program and get a fresh chra for about $400. Turbos direct in AZ has the best prices and quickest turn around I know of.

If the new ones broke maybe they weren't installed correctly or they were cracked before you put them in.

:icon_tup: Yes i meant turbine wheel.

Howard Coleman had a failure of one of the plastic fuel injector spray inserts causing minor damage to his engine.

im never going to use those air bleed sockets again.

I have never had a problem with them. I don't know the effects of taking them out but I figure Mazda didn't put them in for no reason.

having broken one primary diffuser last November i have gained additional respect for handling them carefully... i was amazed where the melted plastic found places to roost.

since nothing but air and fuel contacts the diffuser, and neither is going to cause failure, it is most likely that damage is caused on install, re-install or removal. if one of the two supportive legs gets cracked it is all over and the diffuser will be headed into the motor. i don't think it is a function of age rather the force needed to remove/re-install during the porting process.

i note your diffusers (both) appear to be cracked at the base rings also.

i do believe diffusers should be in the motor but they need to be handled w a great deal of respect.

SFYL:(

howard

the benefits of running them dont outweigh the chance of breaking them. i aligned the notches right and handled them carefully. i really dont know why they cracked during install. need for a new engine + 400$ turbo rebuild, they staying the out!

Ls1

I would hate to see someone go LS1 when their engine failed for a reason not related to detonation or abuse. Ive never personally seen this happen but have now read/heard about 2-3 engines have this failure. Wonder how many original engines and remans fell victim to this over the years when Mazda was in its peak of building S6 remans? Hopefully you will stay the course and stick it out with the rotary.

The diffusers in my 4th motor has seen 130K miles (reused many many times) so Howard is probably correct on this.

Howard have you tried running without the diffusers? Is there any ill effect without one?

I have noticed nothing bad from running without them, just cut the legs off so you still use the round part that fills the notch and has the seal, basiclly what the OP found in his motor after the rest broke, just like in Damiens write up:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fuel-system-upgrade-how-write-up-kgparts-kit-404091/

i love the rotary too much to ever go ls1!

yes im planning to do that since those can never fall into the engine. looking on the bright side, the mod is already done for me haha.

Nice. Next time you troll the rotary section you'll get a vacation for your efforts. Go back to the other engine conversion section where you belong..... see ya at DGRR :icon_tup:

On the subject of this thread, I've personally torn down two destroyed motors from the original brittle diffusers breaking and falling into the motor.

We use brand new ones on all builds with oem injectors, have never had an issue. My personal car uses four top feeds, and I'm kinda glad I don't have to deal with them :)