Now that the end play was set, it's time to actually assemble the front half. Here you see the front counterweight and oil pump. Of course, the proper spacer, bearings and thrust plate were installed under the counterweight, and the stationary bolts torqued to about 17 ft-LBS. Both the pump and bearings were thoroughly pre-lubed. The pump bolts get torqued to about 7 ft-lbs, and red Loctite is very important to keep the bolts from backing out.
After that, the oil pump chain and sprockets were installed. This is a little challenging because everything has to line up. Someone needs to make an oil pump gearset, instead of a chain that will stretch.
A closeup of the pump sprocket key. This is VERY important. Many engines have been lost because this key has slipped out during assembly. The result is that the sprocket begins to rotate on the shaft, the engine looses oil pressure, and then seizes. It's best to super glue it in place, but mine was already thoroughly stuck, so I didn't need to.
The pump shaft bolt gets torqued, and then the lock washer is bent up around the nut. That nut isn't going anywhere.
The front cover is installed. This is another "gotcha". There is an o-ring that seals the front cover oil passage to the front iron. Mazda has changed the design of the ENGINE SIDE of the o-ring groove several times (one from S4 to S5). I'm not going to explain it here, so if you are curious you need to visit the Mazdatrix FAQ
. Suffice it to say that if you are rebuilding an early '86-'88 engine with a new gasket set, you will have issues if you do not follow the Mazdatrix instructions. My front iron was already set up to use the new style o-ring, so I just followed the factory procedure. If you mess this up, it is highly likely that the ring will blow out, and you will loose most of your oil pressure.