View Full Version : OK to Start Engine Flywheel Only?

03-16-2012, 11:23 PM
Wow, I feel really dumb asking this question, but I feel like I have a good reason. I'm replacing the rear main oil seal, and I want to be 100% sure that my newly installed seal doesn't leak.

Is it OK just to bolt up the flywheel, let the car run for a few seconds, then shut it off? Or am I asking for trouble?

03-17-2012, 01:05 PM
Any opinions? The starter will engage with just the flywheel installed, right? Running the engine for a short time with just the flywheel seems safe enough, but I've thought this about other things before, and they turned out to be really bad ideas. Just want to be safe rather than sorry.

03-17-2012, 02:56 PM
do you have an auto or m6? with an auto you will have all the transmission wiring hooked up, it will not start without the neutral safety switch hooked up. also if your auto you have to consider the torque converter not being there, so less harmonics are being absorbed from the rotational mass of the converter not being there, disregard this if your m6

03-17-2012, 03:52 PM
I've got a 6-speed. The main thing I am worried about is something flying off or shaking apart. Hopefully it'll be OK even without the extra rotating mass of the pressure plate. Just have to make sure no wires get hung up in the flywheel, or burnt by the exhaust.

03-17-2012, 04:05 PM
you can start it, its not going to hurt a thing. Think of your motor being on a test stand. Also, the neutral safety switch is part of your shifter assy on an F-body, not part of the trans.

03-17-2012, 06:25 PM
I did mine with no trans for a few minutes, just to make sure everything was ok, etc. It was kind scary watching it spin below though! Def. don't want to touch that!

03-17-2012, 09:44 PM
should be fine just make sure all harness's are clear. and fuel lines

03-17-2012, 10:03 PM
Unless it is a bad leak (highly unlikely) it wont show anyway unitil the oil gets hot and thins out so wasted exercise IMO..... These seals are very good (MUCH better than the old gen SBC stuff) so if you are confident it was installed correctly go with it... If you question it do it again it is relatively cheap..

03-18-2012, 01:53 PM
ok well didnt know that on the safety switch, but either way when an engine is on a test stand they use a flywheel not a flex plate, it is never a good idea to just run an engine without a flywheel on it for any amount of time.. being hes a stick it wont hurt a thing..

03-18-2012, 08:02 PM
Just to update, I ran the engine flywheel-only today, with no problems what so ever. Also, no leaks from the rear main seal :)

Just made sure everything was taped or zip tied out of the way of the flywheel and exhaust. Also put a small piece of foam between the jack and the oil pan to absorb any potential roughness while idling (although there was absolutely none). Then disconnected the coil packs from the main harness and turned the engine over a few times to make sure everything was OK. Finally, started up the engine to check for leaks and admire the spinning flywheel, lol. :eek2: