I'm in the process of my first rebuild here and I just got the engine internals apart. Anyways there is a small scratch/groove on the bottom of the rear rotor housing and I'm not sure what this could be caused from and what to do about it.

I'm doing the rebuild because the car died on startup suddenly one day and then appeared to be siezed. I'm guessing this scratch is from the apex seal that was maybe too thin, fell out and jammed on startup.

Any help on this would be greatly appreciated! Can this be fixed? Machined? Lapped?

Thanks!

Ps. I included a picture, but it's hard to make out the scratch.

 

Can you catch your fingernail on it?

 

Take a closer up pic, and really if you can run your finger across and feel something, I wouldn't use it.

 

Ya I can catch my fingernail on it. It's not REALLY bad, but just enough to catch my nail a bit. I've heard of this test... so what does this mean I should do now?

Thanks!

 

get a better rotor housing

 

Pretty much.

 

Can it not be machined or lapped at all??? I've come so far, it would really suck to have to get new housings!

 

If its an S4 Tii motor i got a housing for sale.

 

The engine is from a non turbo 88 rx7. Can you explain what S4, S5, and S6 refers too. I've heard people saying this but have never understood? That would be awesome, thanks!

 

s4 is 86-88, s5 is 88.5-92 (or something). s6 is FD's (3rd gen's) so i dont know, might be like 93-95 but thats simply a guess. Both s4's and s5's are FC's (2nd gen's). The s5's have more horsepower, are heavier, have different tail lights (the round ones) and a different front bumper. I'm sure theres a million more minor differences between the two but those are the basics. The s5's have llighter rotors and some of the housings are different.

 

You can get it repaired by this company that does repairing and cermet coating, however that costs much much more than the price of just getting one in better condition.

 

if its not too bad you could lap it, but i would reccomend just getting a new housing-dont want to risk it.

 

There is nobody that offers a lapping surface for rotor housings.

New housings go for 500+

James

 

you can find another used one for cheap... but if the scratch isnt deep, it should be ok... also note that it is in the exhaust section therefore it would not have muich to do with compression... but if it damages the apex seal, its not good... i have seen worse scratches than that and they have been ok... my firend had one about an inch long going vertical near the exhaust port.. it was more than a fingernail deep... after the breaking for 500 miles, compression was past 100psi...

its alway's better to use new parts but that scratch isnt nothing..