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40psi compression...really bad??

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Old 01-26-04, 05:18 PM
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40psi compression...really bad??

Hi, this is with my continuing problem to my no spark from leading coil. Sorry for the new post, but I guess this is another topic within itself. Hailers, I did get 5v from the pressure sensor from the Brown/white wire. I use a conventional piston compression tester. In the FSM, it says that I can use it, but it will only read the highest reading from the 3 chambers. I did, cranked for about 10 secs, and only got 40psi. Now, I believe this engine has never been rebuilt, and it has about 130,000 miles on it. Could this be the culprit? I guess I can rebuild...how much would I be looking at approximatly? It's an 1986 gxl...thanks
Old 01-26-04, 05:22 PM
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Umm, yeah, 40 is baaaaaaaaaaaaad.
Old 01-26-04, 05:23 PM
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The engine is in bad shap man. Acceptable compression is 85 psi if I am remmembering correctly. With a number that low it suggests you have lose an apex seal or have really worn seals. A rebuild would be 900-2k dollars for a full build.
Old 01-26-04, 05:39 PM
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Yea 40 is verrrrrrrrrrrrrry low. Does it still run (I missed the other thread)? Good luck man, but when you do the rebuild it will run better then ever!
Old 01-26-04, 05:43 PM
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nope hasn't started since I bought it. Quick question though...what exactly am I looking for? As in seals I would need...I'm trying to price out a rebuild in autozone..what are the seals named?
Old 01-26-04, 05:53 PM
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haha autozone? Yuor looking at the wrong place.

That should help you. http://www.mazdatrix.com/engnumna.htm
Old 01-26-04, 07:13 PM
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He is in Texas. I hope he has a good long distance phone plan. There should be some shops in H town.


Check out our regional section "south section" towards the bottom of the page.
Old 01-26-04, 07:31 PM
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I'm looking at this. Engine gasket set.


Part Name Description Part Number Price
GASKET SET RX7 86-88 NON TURBO 10-2710-8DF1 $161.78



I guess it's not to bad. Labor will be done by my dad, so I can cut that out of the cost. 1k for a rebuild? Where does the rest of the money come from? I thought it was just gaskets/seals?
Old 01-26-04, 07:42 PM
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That just gaskets.. Here is a complete kit for the rotors from mazdatrix.

http://www.mazdatrix.com/getprice.as...MZTX-13-ROTORL
Old 01-26-04, 07:59 PM
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well.... I had a talk with my dad. Seeing as how I'm going to college this year, I can't afford that much right of the bat. Turns out I'm etheir going to junk the car or part it out, and get like a 240 or something. Sad to give my rotary away..but it's just to expensive
Old 01-26-04, 08:07 PM
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Originally posted by xXHybridXx
well.... I had a talk with my dad. Seeing as how I'm going to college this year, I can't afford that much right of the bat. Turns out I'm etheir going to junk the car or part it out, and get like a 240 or something. Sad to give my rotary away..but it's just to expensive
Uh... it's not really more expensive than any other engine rebuild, and it's probably cheaper than buying a 240 by a pretty big shot...

but hey, it's your money.
Old 01-26-04, 08:08 PM
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I think you should rebuild the thing. FOr maybe a thousand dollars or a little more you can have it running again. You can't buy a good car for a grand can you? well not normally.


Santiago
Old 01-26-04, 08:36 PM
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Oh no I can't, but I can pay monthly payments. I can't jump ship and get 1k (which I need all together to build the rebuild), and I need a car asap to get around. Oh and a friend is selling her 96 240 for 1200, nothing's wrong with it exept that it's an auto, and she doesnt like that..so i'm looking at it right now.
Old 01-26-04, 08:57 PM
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Did you do the test with the checkvalve in or out?

Because on some testers, if you do the test with the valve out, it will only read about 35-45 psi, even on a perfect engine!!!! It that case you want to look for 3 (even) bounces.

Once you have confirmed the even bounces, then you can do the overall compression with the checkvalve in...
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