Hi all, I've been having a go at rebuilding my Rex myself (a complete amatuer), you can read the full story over on the British owners forums here: RX8 Owners Club • View topic - Scitmon's Amateur Engine Repair and Restoration Attempt

I'm not getting much help on this thread unfortunately, so I thought I would give this website a go. So my question is, has anyone come across the strange wear that you can see here:



I'm referring to rounding on the top right of the apex seal to the right in the picture.

 

Welcome scitmon .
Have seen a few rebuilds and broken apexs .Not seen that exact issue before but have seen them break off further down the angle part often so it does not surprise me at all . Stock apexs are very brittle and fail frequently in that area.

 

That seal was worn enough that it was rocking in the groove....that resulted in the scallop look on the side..and the tip rounding

Check the groove wear on the rotors....and replace the seals....

 

Thanks for the tips guys, these are actually Atkins seals that are only about 18 months old. The reason I'm breaking it down again so early is because a misfire developed, and compression on two chambers in the rear rotor was down significantly. When i lifted the rear plate, I noticed one corner piece missing. Although evidence of it being dislodged when running is not there (i.e. no significant housing or rotor damage), it would explain the unusual wear on the seal itself and the misfire i think?

The wear on the rear apex seals were around 4.5 - 4.7mm. Good advice to check the rotor groove, I will do that. Meanwhile I will be buying some more apex seals, might go for the cryo treated ones this time...

 

Use OEM Mazda seals this time and thoroughly inspect both the rotor grooves and the housings to be within spec.

 

Interesting, are OEM seals generally considered better than Atkins?

 

Absolutely!

 

Oem seals are almost the best you can find. Most aftermarket seals are overhyped and often fail much faster than Oem. Mazda is not perfect but seriously they have way more r&d funding than most people can possibly imagine.

There are some seals out there that's better than Oem, but let's not get into that for now.

 

Atkins sucks.

 

Thanks for the responses guys, you have persuaded me to go with OEM apex seals.

Another question. If I smooth this nick off with a dremel will it be ok to use? I imagine carbon would soon cover it up anyway?

 

I'm gonna defer to the in-house experts on this, but conceptually, I don't see any fault with your reasoning for reusing that rotor on the basis of resurfacing that nick.