Thinking of buying a motor need to do compression test will this work?

[l3igl3ang]

Hi i was going to buy a 4g63t motor and i want to check and make sure its good useing a compression test. Well its out of the car and has no starter so i read you can turn it by hand/crank but the readings are somewhat off so i was wondering if i could use my ele impact rench to turn the motor faster or would that work?

 

[Calan]

Bad idea for a few reasons. For one, by turning the crank with an impact wrench you run the risk of screwing up the crank bolt and/or crank due to over-torque. Second, the motor needs to be warm to allow for everything to expand to operating conditions before the compression readings will make any sense.

You can turn it by hand and see if there is an obvious problem with a cylinder, but the results can be inconclusive. If it's condition is unknown and it's out of the car anyway and you want to be safe, the best bet would be to pull the head and oil pan and check for obvious problems, and replace all the gaskets, seals, and timing components for a little added insurance.

 

[l3igl3ang]

i will just trun it by hand and see if it has any compression and just go from there. thanks though just wanted to make sure

 

[endeffect0]

If i were in your shoes i would just pull the head off. if the engine is out of the car leave all the manifolds on it and everything, take the valve cover off remove the timing belt head studs and inspect the combustion chamber. should take you less than 30min to take off and put on. then when you take it home replace the head gasket, timing belt and head studs. <which you really should be doing on a used motor anyway.

just my 2c

 

[turboglenn]

unitex trading corp in texas (inporter of JDM engines) has some kind of setup for testing compression out of the car as i've ordered several engines from them and all of them came with a card for being tested before they shipped. THey are easy to find on the web (just google them with the first 5 words of this post) call and ask them how they do it.... I would think there's some way for us average guys other than pulling the engine apart. But either way you should replace all the gaskets just to be safe so you'll end up pulling the head either way.