Just tore my T2 motor down need opinions pics inside
 

Hi every one !

I bought a T2 motor in January and finally got around to tearing her down. It's an S5 engine, P.O removed motor due to hard starts and put another one in. I did notice that it has ,if I'm correct, S4 rotor housings . They have the Mazda Hiroshima stamp on top.

I took pictures of the inside of the rotor housings and wanted opinions on the marks left there in case there are any tell tale signs of anything.The housing with the darker marks is the front, the one with lighter marks is the rear housing. I also have pictures of the irons but will clean those off first before I post unless I shouldn't do that before I post.

Any help would be appreciated ,Thanks

Easy to tell:
Does it have the extra bung on top of the spark plug holes?
The S5 uses them for the knock sensor.
S4's do not have this threaded bung.



Hard to say from the pics, but those look like very high mileage rotor housings or inadequate internal lubrication (i.e. oil metering failed)...
When you run the fingernail over the entire width of the rotor housing, can you feel the scratches? Or, can you feel the wavy surface?
If it's not smooth all the way across, then those are junk, IMO.


-Ted

Thanks Ted I'll check for grooves once I get home in the morning.

So the T2 housing do have wavy surfaces but not entirely across ( *for reference* about half a finger width on either side of the spark plug holes) but in different places some parts are smooth too. I also checked my NA housings and they look good so I'll be using those just gotta swap exhaust sleeves...

I have a question about a deep groove that I found on the irons, all of them have it actually, some deeper that others is this...bad ,normal can it be lapped out?

You can basically ignore like the 1mm edge of the rotor housings...
The triangle assist piece on the apex seal rides in there, and it will always gouge that outside edge.
I try to keep the triangle assist piece of the apex seal on the side with the bad edge - for original motors.
Sometimes you'll see both edges with grooves - this usually means the engine was rebuilt and the rebuilder flipped the rotor housings (front to back, and vice versa), which I tend to frown upon...


There is a limit in the FSM...
It can be lapped out...to a point.
If you lap the side irons too much, you're taking away clearance space in the water jacket o-ring groove.
If you take away too much out of that o-ring groove, it can cause that o-ring seal to squeeze out and cause an engine failure...
So don't go too crazy trying to lap them.
Also, you're going to change the e-shaft end play clearances, so you're probably going to have to swap out the spacer in the front assembly under the front oil cover.

It's probably easier to find another, better shape side iron to replace your bad one...


-Ted

I bounced my rotors off the plates from a severe over-rev.... IE going for 6th, hit 4th @ 143mph with some 275 Hoosier R6's.... I thought the plates were garbage. Chip from Chips Motorsports asked for some pics, which he got, then he asked for the plates. I got back better than brand new plates. I was impressed. Moral is, chances are they can be lapped, however, as Ted said, be careful.

I also had to spend a bit of time resetting the end float

That is either poor lubrication or lean fuel mixture.

I Emailed chips motorsports and they said that they can fix the irons, I think however that I'll buy a better looking used set and send that to them. And remove the T2 diffuser and put in the N/A housings . Guess I'll start a build thread soon...

Buying a better set to resurface and then having them resurfaced is a waste of money to buy the plates