Author Topic: Compression testing your Rotary whatever model you may have .  (Read 9635 times)

Offline clive

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Compression testing your Rotary whatever model you may have .
« on: January 17, 2004, 10:39:28 AM »
One of the first things to check if your Rotary decides to run \'lumpy\' is a compression check to find out if you have lost compression due to one of the three tips per Rotor being damaged or stuck in.

Although the proper way is with expensive Mazda equipment to give you the correct compression readings there are quick ways of at least checking if you at least have compression on both Rotors.

Take out the  Trailing plug from one Rotor [ the top one ] and pull out either a relay or fuse to stop the engine starting and get someone to turn the key whilst holding the throttle wide open.

There are now two ways of checking, one is simply turn the engine over and listen for the \'\'chuffing\'\' that you will hear coming from the spark plug hole this \'\'chuffing\'\' should be constant with no \'\'gaps\'\' , once you have done this to one Rotor then put the plug back in and repeated the process with the other Rotor you will soon realise if the \'\'chuffing\'\' varies at all from Rotor to Rotor.

The other way is by using a conventional piston engine compression tester but you must disable the non-return valve or hold the button on the side in to use these, as the engine turns over you will notice the needle \'\'flick\'\' up and down and obviously you are looking for the readings to be consistent from one Rotor to the other.
All the best Clive

Offline clive

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More info
« Reply #1 on: October 13, 2010, 08:43:59 PM »
Compression test using a piston engine tester:

1. note battery strength. A weak battery will yield low compression results.

2. Remove both lower plugs and wires.

3. remove EGI fuse from engine fusebox.

4. have a friend floor the accelerator pedal, opening the throttle for more airflow

5. insert your tester into the leading hole

6. hold the valve on the side of the tester open

7. have your friend crank the car over for 5+ seconds.

8. observe the needle bounces. You should see 3 in succession without skips, even bounces, in roughly the 30-35psi range.
 
9. let out on the valve now, and let the tester reach an overall compression value for all 3 faces(highest of 3 will be displayed). 115+ is like new, 100-115 is healthy, 90-100 is getting weak(1 year or less in most cases) below 90 could blow at any moment.

10. repeat for opposite rotor. Note difference in overall compression between rotors, which should be no more than 20psi max.
All the best Clive

Offline rsexheaven

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Compression testing your Rotary whatever model you may have .
« Reply #2 on: January 25, 2011, 06:50:00 PM »
If any one could do a step by step with pics, this would be helpful for newbs. thanks :D