I've recently found a donor chassis for the s4fcna, I plan on using the donor subframes
and other parts for a restoration build following suit with other build threads
already archived. Has an engine that according to the owner has been sitting for a few years due to neglect.

My question is can an engine be hand cranked while in the engine bay? and Is it safe for a supposedly healthy engine?

I've read a couple articles on this forum about decarbonizing an engine and pouring MMO in the spark plug slots and THEN
cranking the largest pulley to passenger side on LHdrive to pick up/catch slack coming out of the
Lower Leading plug slots.

Also other articles on compression testing-

I want to know if I have to actually take out the plugs to just [crank check] if it is carbon locked, as I will not
have time as of now to take off the UIM and inspect the inner housing and seals

I also know that if it IS locked that it won't turn, and if it doesn't have a hard time
that it is fine and i can actually then just start it up.

 

If it's locked, it will need to be torn down anyways, so there really isn't much danger. If you pull the plugs, it will make it easier to crank over. Give it a shot. Either way, it's been sitting so you don't have much to lose.

I would change the oil to start, pull the plugs, crank it over while spraying fogging oil into the intake for a few seconds. Install the plugs and try starting it, if you can.

 

No need to change the oil before you know it has compression.

 

Need, no, but if it's in any shape to run at all, I like to at least drain out whats been sitting in there. Just my preference. Cheap dino oil is fine.

 

Yes, make sure it has some oil, put a good battery on it and crank away. Just doing that won't tell you much other than it's not locked...which would be rare in my experience if it's just been sitting. It's not likely start but if it does, I wouldn't run it long before changing the oil and fresh fuel.

To know you have compression you'll have to pull the plugs.
Rotary Resurrection home of the budget rebuild.

 

rotaries tend to carbon lock quite often after sitting for years actually. that's why i prefer pumping in a ton of MMO before even trying to roll one over.

 

I'm not talking about a stuck seal, I'm talking about a seized engine. Is that common for a rotary that's just been sitting?

Unless he's willing to pull plugs and do some type of check for compression, I don't see cranking the engine over telling him much...unless it happens to start.

 

same thing, i've owned 2 seized rotary cars that were locked due to carbon stuck apex seals. massaging them loose, they still ran for years, using the starter to turn those engines may have resulted in crunched parts.

i've worked on many more than that too that were carbon locked, in old non used engines the carbon tends to dry out and grab the seals whether they are pressed into the rotor or expanded.

it's just a warning to be careful with rotaries that have sat for extended periods of time. a little caution goes a long ways.