compression test on a removed engine???

[turboweege]

im looking to buy a nice replacement ka and i want to compression check it to make sure it is good so i dont install a bum motor. i compression checked the engine with all the plugs out turning the crank by hand. it seems to only get about to 90 and to get that i really got to get a good hard stroke at the time of compression. is this a good number for an engine that is being turned by hand and obviusly very cold? or can you not acurately compression check a removed engine? any help would be appreciated. thanksluigi

[extheflow]

hard to say...if they are all close it's probably not damaged badly.some sneaky stuff could still show up. compression test should really be done when warm

[turboweege]

well the engine has 76k on it but i dont want an engine thats damaged at all. and i know it should be warm but thats out of the uestion obviously.

[candela]

Not only should it be warm but its needs proper cranking force(cranking amps/starter)... You cranking it by hand--even with the valves closed-- will yield less pressure than cranking when from a starter.

IMO- like said bove, as long as there really isn't much variance between cylinders with those miles it probably is ok.

[turboweege]

thats what i figured about the cranking force because the harder i did it the higher it went but i can only crank so hard.thanks for the info guysluigi

[turboweege]

if this info is wrong, someone please let me know. because the mileage is not 100 percent. all i saw was a gauge cluster to that effect.luigi

[turboweege]

well, since im still weary im going to add oil to the cylinders to see if the compression raises. any other ideas?

[Nathan]

I can tell you I tried this on my freshly rebuilt motor (it's in the car but no battery to use the starter) and could only get 30psi out of it. Of course, this is without the rings seated, cold, all but one spark plug still in, and with lower compression pistons. I was really just curious if it would work at all. I wouldn't worry about only being able to get 90 out of it

[candela]

Just a thought though: if its really worth it to you why don't you take the head off and check it out? I mean if it looked good to me then i woudl snatch it up in a hearbeat. Sicne teh motor is just sitting there it really shouldn't take to long and it is worth it to open it up and look IMO.

[DAEDALUS]

A leakdown test is a good option. You need to buy, borrow or rent a leak-down tool (~$75 new), and have access to a shop air supply. There's no hope of getting good results by hand with a compression test.