Bought an S5 NA motor and transmission from a running car. It had a holley carb and 13b gsl-se distributor. I striped the motor to bare block to clean up some and then took a close look at the apex seals through the ports. Two of the three apex seals on the rear rotor have pitting on the trailing side of the seal tip. Before the motor came out of the car, I was there the night before and listened to it start up cold and hot. Both times took normal crank time to start and idled great.

I took this with my cell camera. It's hard to hold a mag light and cell camera still enough to get it in focus. I will try to take a better one tomorrow.

The pitting is across the seal most of the way and is on the trailing side from what I can see. Any thoughts?

 

Are you sure it's physical erosion and not just gunk on there tricking your eye? If you poke it with a tiny screwdriver, does it catch in the pits?

A better pic would help, but I know you did your best with your cell

 

It's definitely pitting. I can use a fine point and run it along the seal and it drops into the pits. Also note the rust color on the sleeve. The rear rotor was running lean and was perhaps detonating. Not as harsh as a turbo motor though.

 

Oh wow, that second pic really shows it.

I'm not sure what causes that, but if the car still runs and drives well, I'd just do a tune up, check everything over as best as you can, and then run it until it dies heh.

 

Is it sloppy in the slot?

 

I'll check it later today by trying to wiggle the flywheel back and forth. That should cause the apex seal to wobble if the groove is too loose.

 

I don't think that's a factory Mazda apex seal. I don't know which one that is but there have been certain ones that have been known to do that. Here is a picture of 2 brand new unused seals. The 3mm unit on the right is a factory Mazda seal. The 2mm on the left isn't. I have always stressed that if you aren't going to spend the money to buy Ianetti ceramic seals, you need to stick with only Mazda seals and I will always hold that opinion. I don't care who is using what or how well they work for them.

 

I've started to take it apart. and the flywheel is off already. I have a set of used 3pc oem seals from a decent motor plus a set of coolant seals on the shelf. I don't think this motor has Mazda seals either, but I will know tomorrow when the rear iron comes off.

Detailed pics to follow!