Can anyone help i am rebuilding a Mazda Rotaty 13b engine for use in a hotrod and am battling to tell which housing to by as i do not have the year model of the car is came from. Are there any signs on the housing to tell which housing to buy..
Thank you
Clint Hansen

 

There are a few things to look for. Mazda moved their coolant seals in 86, so determining if the components were made before or after then is key. Any idea how old the engine is? If you look behind the water pump (you might need to slide it forward on the studs) and find an R5 or Y marking, then you have older endplates and housings, and anything 85 and older will work. If you're rebuilding it and the motor's already apart, you can just tell us if the groove for the seal is in the plates or the housings.

 

Post pictures of it and the writing on it as well.

 

Thank you
I have found the marking behind the water pump its R5 and the seals are in the rotor housings, so I gather it is a pre 85 housing i need.I plan to order new ones from mazdatrix.com (84-85 GSLSE Front or Rear 10-100C-N304) is that my best option

Thanks again for you help
Clint

 

Yes. GSL-SE rotor housings are really good to use on any '85 or older engine. However the oil injector fittings caused Mazda to eliminate one tension bolt. There were some R5 rear plates with all 19 tension bolts, so you'd have to cut threads and install an NPT plug into one of them. Otherwise if it's got 18 or even 17 tension bolts like the later nitrided R5 plates from the '80s, you'll be fine.

Count the tension bolt holes in your rear plate and let me know. Don't forget the ones at the lower left and right corners.

 

Wow, I never knew about the oil boss eliminating a tension bolt. Good call, Jeff.