Rotary Engine build Blog

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3 main problems with Rotary Engine Builds

Rotary Engine Rebuilds | 3 main problems


The 3 main problems of rebuilding the Rotary Engine | From teardown to first startup

rotary engine teardown

Mazda REbuilds | #1 The teardown:

Measuring up all the parts to see what isn't reusable. Getting this step right means you won't have to do it again.

When a motor goes down, there usually is a very good reason. Turbo or normally aspirated, the facts always present themselves during this process. This is where paying attention to the details vs. trying to look for reasons everything is ok matters. I like to get motors complete as the signs of what has happened is easier to spot when pulling the plates, housings, rotors at one shot.

As I pull it down, I remove each and every side seal, apex seal and corner seals (along with all the springs) visually noting how it comes out carefully, making notes along the way.

Damaged parts are easy to see. Having the precision caliper handy allows me to take initial measurements. Are there any pinched seals, hot marks, heat damaged areas, tight groves, etc. I've also had customers bring in rotors and e-shaft & stationary gears looking for new bearings to be pressed in. That is where it gets more difficult.

Mazda REbuilds | Second problem:

Prepping the rotors, grinding side seals and assembly. So many errors can be made at this stage. This is where the signals of potential success or eminent failure are created. The details / specs are all available, how you prep them is up to you. Patience, checks and rechecks. Most rotor prep takes 4 hours or more.

Making the leap towards 'all ready for assembly' means that all tolerances are correct (and within specs for the application). Racing engines get different tolerances than street motors. I've heard guys grind side seals to 'zero' gap, that is an invitation for breaking side seals. I have yet to have a motor break a side seal or not make solid compression. Always get this part correct. No excuses and no regrets.

Mazda REbuilds | Third problem:

Putting the sandwich all together while keeping all the parts where they belong.

rotary engine builds

This part should be self explanatory, getting all the o-rings in place, the grey goop at the base of the rotor housings and the level of Vaseline needed to hold everything in place. Sliding in the apex seals / springs takes experience to make sure they are correctly placed. How many people have lost that corner apex seal or having it pop out at the wrong moment. These things happen. Be prepared, execute carefully.

Rotary engine builds don't have to be a nightmare. If you are going to put it all together at home, do it right or have someone else do it right for you.

Start Up: The proof is going to be in the first minute when you fire your beast up. The right setup, check all the boxes (fluids, timing, fuel, etc.). Get all of these things correct and you still have a chance of a motor that will perform as expected and last. Choose carefully.

The reality is front and center, if you choose to take shortcuts, it will bite you at some point. We work hard to give the rotary engine the stature it deserves by building solid motors.

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Topics:   rebuilds

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