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First ROTARY rebuild,housings usable?

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Old 05-17-18, 01:56 PM
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First ROTARY rebuild,housings usable?

So i finally pulled apart my s4 T2 engine,after blowing it up last fall. The car had 110k miles,assuming the odometer was correct,and im not entirely sure the OMP was working but i had premixed the car since ive owned it.
I was expecting to find the apex seals in pieces,but actually it appeared to be coolant o ring failures,Unfortunately the car sat for a few months with the coolant eating away at it, but it does not to appear to have seriously corroded everything,theres some black stain/corrosion from the coolant on the irons.As of currenltly my list of parts includes the following,new rotor bearings,a full o ring kit and apex seal kit,maybe oversized engine bolts/dowels.

I do have all of the tools needed for proper measurements, and have rebuilt engines before,but this is my first rotary and im actually happy it finally blew up so i can rebuild it But im unsure if these housing's can be used or if they need to be replaced/surfaced I found various things on the internet about people running them with wear as long as you cant feel the lines with your fingernail,and others say not to.I also found a tiny chip in the rotor i was curious if that will need to be replaced or not. This will be a budget build but in the sense that its done properly,im not just going to slap new seals in and call it good.
I have a few pictures and can definitely get more,Ive cleaned everything up since taken these pictures and a lot of the corrosion is gone minus the black on the chrome of the irons.
My overall goals for it are obviously a rebuild firstly,and to make 350+ when its done.

I appreciate anyones feedback







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Old 05-17-18, 03:11 PM
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Good luck. I am awaiting the day to rebuild my 1st as well. Looks fun.
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Old 05-18-18, 08:10 AM
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General rule of thumb is if you can catch your fingernail on a groove on the surface of the rotor housing or the surface of an iron it needs replacing.

From the pictures everything looks OK, not amazing, but useable. The small divot on the surface of the rotor is from an apex seal breaking, did that motor have a broken seal? Or it could have been from a while back and it was rebuilt. I've built motors with "scars" in the rotor surface, just as long as they are flat and no sharp edges it's fine to run. Run a file over it to make sure it's good and flat.

Read and watch videos on the process. You will likely screw something up your first time, you have to be prepared to pull the motor and go back through it again, but that's how you learn.

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Old 05-18-18, 09:19 PM
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i think those rotor housings would clean up and be passable for a stock car. for a high hp car, you should clean em up and sell em, and just buy new ones.

everything else you should measure and replace as needed. you end up with a better engine, and its usually less money. with higher hp you want to be more picky.

and since its a T2, check EVERYTHING on or on top of the engine.

then you get to replace all of the rubber cooling system parts, inspect or replace the spark plug wires and fuel filterS.

can you tell i'm just finishing up a t2? i tested ALL of the sensors, most of the wires on the harness, the metering lines. all the coolant hoses are new, along with the water pump, belts, filters, all the o rings, gaskets and all that.
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Old 05-19-18, 10:15 AM
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Originally Posted by j9fd3s View Post
i think those rotor housings would clean up and be passable for a stock car. for a high hp car, you should clean em up and sell em, and just buy new ones.

everything else you should measure and replace as needed. you end up with a better engine, and its usually less money. with higher hp you want to be more picky.

and since its a T2, check EVERYTHING on or on top of the engine.

then you get to replace all of the rubber cooling system parts, inspect or replace the spark plug wires and fuel filterS.

can you tell i'm just finishing up a t2? i tested ALL of the sensors, most of the wires on the harness, the metering lines. all the coolant hoses are new, along with the water pump, belts, filters, all the o rings, gaskets and all that.
Yeah this car wont see massive amounts of power,especially since its my first rebuild i would not risk the money.
Ill probably buy new,apex seals/side seals/springs etc because of the little corrosion it had,newrotor oil rings,then check the irons for straightness,and the e shaft.Defnitely need new rotor bearings as well as stationary gear. The thrust bearing and oil pump looked fine.What else is there to measure?
That's why i was hoping i could re use the major components.
As far as seals,gaskets and other maintenance/wear parts those will all be new too. And ill definitely be going through the wiring and sensor before the engine goes back in as a i have a Haltech ecu to wire in.
Originally Posted by DaleClark View Post
General rule of thumb is if you can catch your fingernail on a groove on the surface of the rotor housing or the surface of an iron it needs replacing.

From the pictures everything looks OK, not amazing, but useable. The small divot on the surface of the rotor is from an apex seal breaking, did that motor have a broken seal? Or it could have been from a while back and it was rebuilt. I've built motors with "scars" in the rotor surface, just as long as they are flat and no sharp edges it's fine to run. Run a file over it to make sure it's good and flat.

Read and watch videos on the process. You will likely screw something up your first time, you have to be prepared to pull the motor and go back through it again, but that's how you learn.

Dale
The engine doesnt look tohave been rebuilt, 100k miles and i was told it was in storage until the early 2000's

Not sure on any of the rotor seals breaking,It could have been a terrible combination of that plus the o ring. Initially when i "blew the car up" was doing a pull through a tunnel and the car died,ran like it had a blown apex seal,i pulled over and noticed that a vaccum line had popped off. I assumed it had definitely broken seal ,but when i pulled the engine apart everything was intact minus the coolant o rings.

ON a side note,also have a NA S5 engine that i just tore down,bought it non running for the shell and was told the engine was just rebuilt. Turns out it suffered the same fate as my t2,coolant o rings were leaking but i let this one sit even longer,it looked terrible,whoever rebuilt it definitely was an amatuer so hopefully i can avoid doing the same as them, There is also a considerable amount of wear on one housing vs the other
The rotors were seriously corroded but cleaned up fine, bearings looks new though so i may press them out and re use them haha


GROSS The equivalent of a blown head gasket,and why you shouldnt let an engine sit.



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Old 05-24-18, 06:07 PM
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,Just clean everything up and use it. 2000 grit sandpaper and a razor blade works great for sponge carbon and surface carbon. A pick and pocket screwdriver works great for the coolant seals, apex and side seals, and oil control rings surfaces. I always use GUNK engine cleaner in the aerosol cans for cleaning parts. After you clean everything off spray it with WD40 or PB Blaster etc to protect from flash rust. As long as the seals and springs still fit properly, the mark on the face does not matter, if it were me I would just lightly file it smooth


I wonder if a spark plug tip could have been ingested and damaged that rotor?

One thing I would check though, look very closely at the coolant seal surface on the housings. Check for cracks...

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Old 06-06-18, 08:33 PM
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Good info and photos!
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