I suspect one of the side seal to be gone one the rear housing of my engine. Did a compression test and have one face without compression in the rear. Front is good all around.
I basicly have two questions :
1- What are the usual causes for the side seals to go bad ?
2- Do they usually cause extensive damage to rotors and housings ?

What are the chances that my core (housings/rotors) is still good for a rebuild ? Any input would be appreciated.
Thanks !

 

1 bad compression reading on a rotor is usually the sign of a side seal since an apex seal would give 2 bad readings. I read something somewhere a while back about what causes side seals to bad vs apex seals, but I don't remember where or what the cause was. As far as the core being salvageable, its unpredictable. Have to open up the motor to find out.

 

wHY DOES rear rotor always goes out first? Does the front run cooler?? Or does the rear rotor get lean out, maybe the OMS don't work well?? ANy one know and how to prevent this??

 

The front is cooler since it's directly behind the fan.
On turbos, the rear rotor takes the overboost fuel cut.
Due to the (turbo) fuel system, the rear secondary is the last to get fuel - any degradation in the fuel system would affect this fuel injector first.

Prevent it?&nbsp Rebuild the engine every 100,000 miles.


-Ted

 

But what is usually the cause of a blown side seal ? I expected the apex seals to go first, like on my last engine.

 

Apex seals usually do go first.
It's either a bad build of the engine - rebuild? - or bad side seal build quality.
It could be the engine sucked something in and just happened to take out the side seal.
I'd imagine there's more damage in the engine besides the side seal...


-Ted

 

So why mazda did a fuel cut off not a spark cut off?

 

Official reason was to suppress emissions and not hurt the cats.&nbsp Ignition cut would dump raw fuel onto the cats, which could damage them.


-Ted