J.S.J

Guys,
I have a bit over 1200 miles on my rebuild and took a compression test at about 500 and found the rear rotor has uneven compression as compared to the front rotor. Using a typical compression tester it's hard to gage the pressure difference but can clearly see its not smooth as the front rotor. I assume its not likely an apex seal as it seems to be only one out of the three pressure readings. My engine builder said it might be a spring not broken in but surely thats spun a bit to his side of things. I have gaged the power balance from one rotor to the other and the front rotor is stronger and there doesn't seem to be a miss when it runs alone (other than the rear rotor as its shut down electrically).
There is a constant miss at idle and once in a while it smooths out but 90% of the time its missing on one stroke. The engine has a warranty so What do I do now? I don't have a Mazda compression gage but I thought I could get the readings on film and look at them on my PC. There I could slow down the action and maybe see the readings clearly.

J.S.J

I relize this is a question only a experenced rotary tech can adress but No one?

I thought I would add the lower mesurement is not real low its just not even.














Hope this gets someones attention

P'cola FD

If it's only on one rotor face, it could be either a stuck, collapsed, or a broken side seal. If the engine is past the break-in period, then I would be looking to possibly cash in on that warranty.

J.S.J

What would you consider the brake in period? The engine is a typical rebuild no special Apex seals etc.

P'cola FD

Everybody has a different break-in period. Mine is 500 miles at no boost, then an oil change, and the next 500 miles starts introducing more and more boost. That is just me, though, as I am very conservative.

What I meant by break-in period is whatever your engine builder told you to do for break-in.

gambone

iTrader: (3)

I've seen a lot of uneven comperssion comeing from the rear rotors and mostly it's do to some kid scoreing the side houseings. So your builder will take it apart and my find this to be the case, but we all know you never over revd it !

J.S.J

I have not seen over 5500 rpm. I have not seen full boost as well. I am setting up a video camera on my laptop and will see the readings slowed down. The builder did ask around for input within the builders community and said it could be a side seal as well as a corner seal but didn't mention the housing. I will be hard pressed to send it back anyway. Its likely I will open the engine and document what I find. If it not to the liking of the builder I will negotiate a deal. He knows I have 20 of tune up and drive-ability experience and can't expect me to leave it up to him. If push comes to shove I will file against him via my credit card account and hit him with a small claims doc. The minute the engine is in his hands the odds shift to the house. I am going to do as he asked. Run the engine completely through its brake in which is 2500 miles and see how things look then. Until then everything is documented.

Glassman

iTrader: (1)

Find a Factory compression tester or go to Mazda and have them do it for you. Once you have the print out, contact someone like Jeff McCall at Rotary power to interpret the graph for you.

As far as tearing into this thing without letting the builder honor the warranty, I do not recommend doing this. It is completely unfair to the builder.