Can I do a leakdown test to my engine while itis o the engine stand? Im looking for the cause of my blowby problem. I couldnt do a test while it was in the car since my header dont allow my any room to get the plugs off or any other fitting in the hole.

 

but,, you will loose some accuracy.. I would say the numbers might be slightly worse (no more than 2percent) bc the motor is not at operating temp.

 

do leakdown testers come with directions and do they come with everything I need to use it. I already have a copressor.what numbers should I be looking for and what are the tolorences for the engine?

 

but,, the basic premis is,, for a two gauge unit, set the air delivery gauge to read 100psi by using the regulator on the tester. Then read the results from the second gauge. Any thing below 10percent for a motor that has been inservice for a long time is normally pretty good. New motors are in the 5percent range in most cases.

There are some one gauge units that operate slightly different.. but im not familar with how.

 

Yes. The results should be close enough. Then again, if the engine is in a stand, 17 bolts will get a head off and you can SEE what's going on.

 

Vader, I ask in a another post if I could see anything that results from a broken ring but got no response. So your saying that if I pull the heads, I will be able to at least see something that may stear me closer to where my problem? Im putting new heads on this engine anyway so I have to take these junk heads off anyway

 

It isn't likely that you would be able to see a cracked ring directly. However, if you do indeed have a cracked ring, removing the heads would likely reveal the gouging of the cylinder wall created by a cracked ring. If you find damage from a broken ring, you'll be throwing away the pistons as well, since that usually means the cylinder has to be bored to clean up the damage.

I cracked a ring in a race and drove/nursed the car home (less than 40 miles) and had a 1/8" deep slot worn into the cylinder wall when the heads came off. That cylinder got a sleeve, and the rest were bored to match.

 

according to GM (and I take this with a pound of salt.....) anything less than 25% leakdown is acceptable, all cylinders within 10% of each other.

Personally, i am of the opinion that a 25% leakdown means Rebuild time.