Compression Numbers

[xzeror]

Buying a 2jz and it does not have the starter nor flywheel. So the seller assured me that the engine did indeed have compression and decided to hand crank it over and with 3 crank by hand he got the compression to 130 in each cylinder. Hes garanteeing that there is atleast 150+ in each cylinder, and that it read 160 when he did a compression test when he first got it.

What i want to know is if hand cranking does indeed give lower numbers.

 

[xzeror]

anyone have any imput?

 

[soapra]

Do a leakdown, best way to know for sure.

 

[xzeror]

thanks for the advice

 

[te72]

You ever turn an engine over by hand? I seem to remember hearing air leaking out of the engine when doing that a while back. Wouldn't surprise me if you can't get proper compression numbers without the starter doing the hard work for you, but like was suggested, a leakdown is probably the best idea here.

 

[suprahero]

Turn the motor over by hand? No thank you. I won't even use Vonda's new broom because I can't find where the push button start is. Manual labor FTL.


Buying a motor from someone is easy..........if you trust them. If they're not a reputable shop or someone you trust then I'd shop around. Good luck.

 

[mkiiichip]

Its a 2jz, what are you worried about?

Id be more interested in sludge buildup under the cam covers. Thats a sure fire way to find if the motor was taken care of, as far as maintenance goes.

And the guy that told you he did a compression test while cranking the engine by hand, is a asshat. I would bring my compression gauge and a breaker bar and ask him to duplicate those numbers on just one cyl.

 

[te72]

And the guy that told you he did a compression test while cranking the engine by hand, is a asshat. I would bring my compression gauge and a breaker bar and ask him to duplicate those numbers on just one cyl.

I'd be surprised now that I think about it. When doing a test, aren't you supposed to crank the engine for something like 4-5 seconds with the starter? No way in hell a person could turn over an engine anywhere near as fast, certainly not enough to generate meaningful compression...

 

[bioskyline]

im inpressed you got 130 by hand!

 

[steveyblack]

Takes about 10-15 minutes to hook up a flywheel and started. Just hook the starter up to a battery then jump it to crank it over. Test then. Id still do a leakdown though

 

[dirosa]

it's probably easier to just get an electric impact gun (battery power or corded) and just crank it over from the crank pulley bolt no? the battery powered impact guns are so good now, i've seen guys change wheels with them, so getting the engine to turn for 5 seconds a cylinder should be doable.

 

[steveyblack]

it's probably easier to just get an electric impact gun (battery power or corded) and just crank it over from the crank pulley bolt no? the battery powered impact guns are so good now, i've seen guys change wheels with them, so getting the engine to turn for 5 seconds a cylinder should be doable.

please dont do this, I see a thread in the future asking why his crank bolt is seized.

 

[dirosa]

if you pull the spark plugs, and insert the compression tester 1 cylinder at a time, there is no way you'll be creating more than 200 ft-lbs of torque........and search around, crank pulley bolts are supposed to be ridiculously tight, this will in no away torque it down more than most already are.

 

[te72]

You can't break the torque on the crank bolt on a JZ by hand if the engine is on a stand or out of the car, the spec on that bolt is over 200ft-lbs. Tried doing that myself, and the entire engine started rotating, nearly tipped the stand from the weight...