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

 

Just a guess, but I'd think you'd see +-5 from testing cold like that.

 

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.

 

What were the compression numbers on each of the rotor faces?

 

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

 

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.

 

We did this in a garage at my friends house, make sure to plug the front oil cooler port.

 

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.