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Worst Rebuild Ever

 
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Fri Jan 20, 2006 8:47 pm    Post subject: Worst Rebuild Ever Reply with quote

Okay, I bought a core motor on eBay recently. It was mis-listed in the "Interior>Window Motors & Parts" section and all the usuall the keywords were missing (no "RX7", "RX-7", "Rotary", etc.), had no picture and specified "no shipping". The description was not great, but it said it was a 91 Turbo II engine, zero-miles on a rebuild, ported, with 3mm apex seals. The guy paid $3,000 for it several years ago and then let it sit in his basement for years. He also said "consider it junk". I won the auction for $61.25 after confirming he was willing to put it on a pallet if I sent a freight company to pick it up.

The engine showed up today, pretty much as described. It is a Series 5 Turbo II block and it had not been run since being assembled. The bad news is that it would have never run anyway, since it was assembled with an incompetence unrivaled in the history of the rotary engine. First of all, the thing was LOCKED. Usually with a stored engine, a little rust or carbon can lock the rotating assembly, but this was actually because the guy ran the tension bolts down to something in the neighborhood of 300 ft lbs, as well as screwing up the thrust bearing assembly. When I took it apart, I found that the "porting" was unbelievably bad. I will post pictures later, but imagine what it would look like if rats could chew through metal. It was really that bad. Also, there was NO clearance between the side seals and the corner seals and only half the corner seals had springs behind them...which is weird, as the missing corner seal springs were all on the same half of each rotor. The rotors had 2mm seals, not the 3mm ones the buyer was told by the builder. There are several other issues, but those are the big ones. On the bright side, the apex seals were brand new, the water seals were new, the rotors and rotor housings were in decent shape, it had a competition oil pressure regulator, and more.

Regardless, I got a smoking deal, but I feel bad for the previous owner who got HOSED.
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Blake Qualley
Pineapple Racing, Inc.
(503) 233-3878
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Mon Jan 30, 2006 9:29 pm    Post subject: Reply with quote

Here are the promised pictures of the "porting" of this abominally bad engine. I also posted this in the Porting section. Unbelievable.






I put squiggly marks where the port edges are extremely uneven and arrows where other attrocities have occured (like porting into the area where the oil seals ride). I will not bother explaining all the less obvious incompetencies. This is really, really, REALLY bad port work, as should be obvious to even a casual observer. It looks worse in person.
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Blake Qualley
Pineapple Racing, Inc.
(503) 233-3878
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Mon Jan 30, 2006 10:07 pm    Post subject: Reply with quote

For contrast, this is what good porting looks like. Obviously, this example is of a bridge port, but the principle is the same...it should look clean and smooth, with nice transitions in cross-sectional area. Doesn't need to be this shiny, though. A little texture helps prevent fuel wetting.


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Blake Qualley
Pineapple Racing, Inc.
(503) 233-3878
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Mon Jan 30, 2006 10:13 pm    Post subject: Reply with quote

This is a photo showing one of the rotor housings in the (badly) "rebuilt" engine (with zero miles) and what its mate looked like after I cleaned it up, the way it should have been in the first place. Clearly, the individual who "rebuilt" it just scraped off the big chunks and threw it all back together with no real effort at cleaning. Amazing.


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Blake Qualley
Pineapple Racing, Inc.
(503) 233-3878
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Jingyee
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Joined: 11 Jul 2005
Posts: 85
Location: Portland, OR

PostPosted: Tue Jan 31, 2006 2:57 am    Post subject: Reply with quote

Wow that is horrible, I coulda done a better job porting lol.
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Blake
Been there, done that


Joined: 12 Jul 2005
Posts: 135
Location: Portland, OR

PostPosted: Tue Jan 31, 2006 6:06 pm    Post subject: Reply with quote

Oh, by the way, the cleaned rotor housing in the above picture proved to be junk (by our standards) after it was cleaned up. There is a narrow band of chome flake along one edge. Technically, it's still within Mazda's specs (permitting up to 2mm chrome flake), but no one in their right mind would put it into a quality rebuild. Sure, you could get away with these rotor housings for a year or two, but why go to all the effort and expense of a rebuild if you don't expect the engine to last longer than that? Unless you clean your parts thoroughly, you can never properly inspect them to identify what's good and what's junk.
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Blake Qualley
Pineapple Racing, Inc.
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