Another question, engine compression testing, sitting motor

[Denny]

Hey again, when I was on SB I ran into a fellow SHO owner who mentioned I could check a sitting engine by spinning the crank with a wrench to make sure it wasn't locked up or anything. Later on, I just got the idea, can I do a compression test on it and spin the crank? Will it build up proper compression? Would the crank be harder to spin as the compression got up?
As well, if this motor has been sitting with oil, would the heads and valves be dry? Oil is in the plug wells, could that be a sign?
Thanks again!

 

[rangerj]

Denny,

You can turn the engine over by hand in order to determine whether or not the engine is siezed.

Can you turn it over fast enough, by hand, to get a good compression test? NO WAY!

I would pull the plugs and spray some penetrating oil in the cylinders and let them soak a few days before trying to turn the engine over. Just a thought. rangerj

 

[Underdog]

Denny,

Simply install a starter motor on the motor. That will allow you to turn it over with enough speed to get some compression readings.

Additionally, there is assembly oil that you can pick up at Pep Boys that we use when building new engines or, if you have the valve covers off, you can just pour some oil over the heads and drain the excess.

 

[Denny]

Thanks guys, I figured I wouldn't be able to manually build up compression. If I take the valve covers off, would normal oil be ok before spinning the crank around? Oh yeah...since there was a tough time getting the crank bolt off of my running SHO with it in the car, is the crank bolt going to be impossible with the motor out and no way to bump the starter??

 

[SHOpar]

rangerj:
You can turn the engine over by hand in order to determine whether or not the engine is siezed.

I got burned doing this to a turbo Mopar junkyard motor last June. The guys said came in running perfect a few years prior, but had a trans failure. It also showed only 40K on it.

I spun the engine to make sure it wasn't siezed, and then installed it in the car. Unfortunately it had almost NO compression and took forever to finally start. I let it run for a few minutes only to find the temp gauge pegged and it blowing TONS of white smoke. I turned the car off and found that all the coolant had made it's way to the oil pan. There's either a massive headgasket leak, or cracked head or block. Either way, this engine is toast.

It was quite frustrating, especially since I had spent 3 days straight getting it back together. I also lost all enthusiasm on this car, and it still sits out in the field waiting for me to find another motor. I will never buy an engine without a guarantee again...

 

[Denny]

Whoah!

So what can I do to inspect this motor to make sure coolant hasn't leaked around or that anything isn't bad? Anything?

 

[SHOpar]

Denny:
Whoah!

So what can I do to inspect this motor to make sure coolant hasn't leaked around or that anything isn't bad? Anything?

You could always run a leakdown test on it. As long as you have an air compressor, the leakdown gauge, and something to rotate the crank into the right position, that's all you'll need!

The leakdown test would be a good indicator of whether or not the engine is okay.

Where is this engine? In a junkyard? If so, any competentjunkyard should be able to do a compression and/or leakdown test for you before you get the engine, and many junkyards have warranties.

 

[Denny]

It's in a SHO owners garage currently, waiting to go into a certain 90 SHO