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Comp test results on a motor thats out of the car...

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Old 05-21-08, 10:07 PM
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I "lost" my emissions....

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Comp test results on a motor thats out of the car...

ok so lets say theres a s4 n/a mazda reman thats been sitting for a couple months, that is out of the car.
by jumping the starter you get 100 psi of compression on both rotors.
what could you reasonably expect to see on that block when warm?
thanks
ben
Old 05-21-08, 11:07 PM
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rotors excite me

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Just a guess, but I'd think you'd see +-5 from testing cold like that.
Old 05-22-08, 02:37 AM
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isn't compression guaranteed to be higher when warm? With all the metal expanding and extra oil sloshed all over the rotors that sure seems like it would be the case. That motor might be near perfect compression.
Old 05-22-08, 07:45 AM
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What were the compression numbers on each of the rotor faces?
Old 05-22-08, 10:59 AM
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how did you do this exaclty? I got a used motor sitting right now, and i was assured that it would run because it did when the PO took it out of his car and it was still running. Could you explain how you hooked up the starter? is it connected to the transmission? I want to do this on an engine stand. thanks.
Old 05-22-08, 12:23 PM
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Originally Posted by Asterisk
how did you do this exaclty? I got a used motor sitting right now, and i was assured that it would run because it did when the PO took it out of his car and it was still running. Could you explain how you hooked up the starter? is it connected to the transmission? I want to do this on an engine stand. thanks.
Pull starter
Old 05-22-08, 03:31 PM
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I "lost" my emissions....

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I didnt do it, another guy did that Im hoping to get the motor from, and yes the tranny was attached and so was the starter.
Old 05-22-08, 03:43 PM
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We did this in a garage at my friends house, make sure to plug the front oil cooler port.
Old 05-22-08, 03:47 PM
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how did you do this exaclty******************************************* ****************

Jumper cables from battery. Positive cable to *B* in the jpg. Negative cable from the battery to preferably the LONG bolt the holds the starter on or at least one of the bolts that hold the transmission to the engine.

Then bridge the gap b/t *B* and the SMALL terminal on the starter solenoid. Use a screwdriver shank if needed to bridge the gap.

Starter now rotates the engine if the battery is any good.
Attached Thumbnails Comp test results on a motor thats out of the car...-kif0974scaled666ha9.jpg  
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