What would a good "manual compression test" look like?

[spipedong]

Hi guys,

I've been looking at engines today and have gotten some good information and offers (thanks aaron), but I got a reply from one person who indicated that they had done a leakdown test with good results and a "manual compression test" with 100psi on all 6 cylinders.

I'm assuming this would mean throwing the tester on there and cranking it over by hand a few times with the crankshaft bolt.

100psi seems reasonable to me since it's being hand cranked. As long as the numbers are all even with each other with no/minimal leakdown this would indicate a good condition engine, no?

 

[p5150]

It is possible to to a compression check with the motor out of the car. As long as the flywheel or flexplate and the starter is installed then the starter solenoid can be bridged manually with a spare battery to turn over the motor.

The motor has to be secure though - it might move around so be careful and make sure it is secure so you dont get hurt.

 

[p5150]

And as far as the readings go, its probably good but there are a few things you should look at.

Find out how they performed this test. If they were using an air gun to rotate the crank then you may have a main crank pulley bolt that has been over torqued. Not a big deal - I would just recommend changing it if that is the case.

I think its a plus that all of the cylinders are uniform. Usually, an engine with a problem will indicate one cylinder with lower compression than the others - except in the case of high-mileage motors which may have all cylinders uniformly worn......

 

[spipedong]

Cool, thanks for your opinion.

I went ahead and purchased it anyway so I hope it works out.

 

[becauseican]

Normally a 1jz should see about 175 psi on each cylinder, but that is with using the starter to crank it over.

 

[spipedong]

I assumed that the numbers would head upwards when everything was cranked with a real starter, and to me the leakdown numbers seemed to indicate that nothing was really leaking in there.

Mostly it was so cheap because it's a soarer 1JZ with a cut harness and no ecu or ignitor, but I'll be swapping my oil pan and all accessories onto it so no big deal there.

 

[xarewhyayen]

Are the leakdown results verified somehow? pictures?... what is a "good leakdown" to you?