So I got the engine apart. This engine is a Malloy reman, almost 6 years old with 29K on it running Evans NPG+ (never been changed either).

Here is the reason for the low compression: Note the lower 2 apex seals. Each has a piece cracked off the end.


Looks like I need a new housing:



Look how clean the coolant passages are:



Another look at the coolant passage:


BACKGROUND: I lifted only the rear rotor housing and rear end plate. I have not removed the front rotor housing or intermediate plate. The front has 95-100 psi of compression on an piston tester before disassembly.

QUESTION: Would it be prudent to leave the front rotor housing, intermediate plate and front plate unassembled and just rebuild the rear section as in new housing, new apex, side seals and corner seals and water o-ring?

Has anyone done something along this line, i.e., a partial rebuild?

 

Could you? Sure. However, you always run the risk of having the cooling passage sealing compromised since the tension has been released with the tension bolts removed. I would in the least replace the coolant seals even if you reuse everything else. You've already removed the engine and that's the hard part. Why take shortcuts now?

 

 

I would go with new seals all the way. Its easier than pulling the engine again. I have done what your suggesting on an old 4 port 13b NA many years ago, when I had to scrape every last penny to put an engine together. It worked, but that was a low hp NA not a turbo.

 

Definitely disassemble and rebuild the entire engine.

The chipped areas of the apex seals are a common failure point.

The cleanliness of your coolant passages is enough to make me consider using Evans, btw.

 

Measured voltage is 0.08v with a voltmeter set to 2V. Has not really changed in almost 6 yrs. coolant however, looks black but I was told that was normal. $42 per gallon though.

Here is another view of the coolant passage in the intermediate plate:

 

Do you have speculation on a cause for the chipped seals?

 

Yes.

Background: Engine tuned over a year ago by Steve Kan, running 4X850 injectors, Supra pump, Sard PR. 311 rwhp 268 torque at 12 psi. I put in 10,000 miles on this tune with no problem.

In early August, I put in 8 oz of SeaFoam in the crank to clean out the internals. I was supposed to drain it but forgot and went to work. It was 70F, low humidity, water temp at 86 and I floored it. Got to 12 psi and heard a loud pop.

My guess is that the seafoam, a solvent was injected into the combustion chamber and caused the detonation. Since the rear rotor always run a little leaner than the front, it detonated.

If I had my Aquamist installed, it would have probably saved the motor.

Right now I'm debating with myself whether to rebuild or get a new Malloy.

 

Given the suspected detonation and for the reasons Mahjik mentioned, I'd go ahead and fully disassemble before making the decision. I've heard some of the remans are a little sketchy. I'm not sure if Malloy's are any different.

 

The ones that Malloy are selling are brand new ones, not a reman. The blown engine that I have now was a reman with new housing, rotors and seals. It lasted 6 yrs and my own idiocy.

 

My theory is that the apex seal chips it's tip from snapping across the extended spark plug boss as noted in this image. Note the carbon stains.

Solutions include colder plugs, and improved coolant flow.

Barry

 

But note where the gouge started: right at the trailing plug so I don't think your theory is correct. In any case, I'm running 9s all around with Evans NPG+ and 2 oil coolers.


New QUESTION: has anyone rebuild without taking the front cover off?

That front lock nut for the eccentric shaft is a bitch. I could not move it with my IR700 at 130 psi.

I don't see the point of taking the front cover off when the engine has only 29K on it and no front cover oil leak.

 

That front E-shaft bolt can be a REAL pain to get to come off. DJSeven helped me with mine. Great guy! He used a torch on that sucker. Left it on there for a few minutes to get really hot & then hit it with an impact. Finally came off.

 

poman, you don't see the point?

The engine is already out. I think you'd be crazy not to completely disassemble everything. Check, measure, clearance, reseal. If you're hesitating b/c of inexperience, take it to a local reputable builder. Hell, box it all up and mail it to me and I'll take care of it for ya

 

That is a typical detonation failure.Here is another(from my RX8 turbo).The 3rd apex seal was jammed in the rotor.

 

Thanks for the offer. I ended up buying gracer-rx7 used motor. I thought about plunking down $5K for a brand new motor but wife 1.0 isn't having any of this. So the most economical and timely way for me to get back on the road is to drop the used motor in while I take my time rebuilding the other.

I don't know about you but I can see a decade of really bad economic time ahead. Money saved is money earned.

 

sounds like a good solution.

now you can rebuild your engine and take your time doing it.... or just send it to a shop and have them go over it with a comb while the "new" engine gets put to good use.

 

Pick up some ALS or RA superseals while you have it apart.

 

Yes, and defininetly rebuild and clearence the whole engine.

 

Condition of the turbo with about 40K on them at 12 psi.

 

damn check out that crack in the mani.. may as well ditch the twins when you get your self built engine in...

 

I got a good mani with no cracks in it for sale if you need. Setup for non-sequential though.

 

That's an odd spot for such a large crack to develop, typically that happens in between two openings and runs horizontally....