The final piece to my 7.3 rebuild is coming in this weekend and I hope to get it on and then stick the motor back in soon before it starts getting bitter cold here in PA. The truck is a 1995 F350 CCLB 7.3 with an automatic E4OD transmission. Since every gasket on the motor is new and I did a fair amount of custom work with E-fuel and turbo set up I want to make sure the motor is running good/leak free before I spend all that time bolting the transmission back up just to find I have some sort of major leak and have to pull the motor back out to fix it. That being said is it possible to start these motors with the transmission not bolted up? I know I'll have to bolt the adapter plate on for the starter. I'm assuming I'll have to ground the neutral safety switch wire in the harness that connects to the transmission? Is there any other weird electrical connections in the harness that will prevent me from starting this motor with the transmission not bolted up and not connected?

 

I wouldn't do it myself partly because the mass of the transmission and torque converter aren't there and that will probably affect the running dynamics of the engine. I'm probably being overly cautious but that's not something I'd try with my own truck. Maybe a junker motor though, just to see what happens. XD

 

Unless the pan or timing cover is leaking pretty much anything else can easily be done with the engine in the truck.

 

Yes you can start it up without transmission.

I did once on my S10 years ago.. but pressed the damn clutch pedal without a trans installed.. blew my clutch line out.

 

But you had an S-10, NOT a Ford with a powerstroke

 

Don't see what the difference is. I might be ignorant for assuming.. but probably not. Sure the 7.3 cost more and is a diesel.. but I'm GUESSING it's got a flywheel bolted to the crank like every other motor.

It's got a computer.. that's only issue I could reason with. Off the line.. I'm thinking they probably test their motors without a transmission.

 

On older GM engines, the starter bolts directly to the engine block not the transmissions like Ford does.

So no way to mount the starter unless you have a old bellhousing you can use.

 

The 7.3 starter bolts to the adapter plate that is bolted to the engine. You can start it out on the floor if you want. The flex plate on these are not flexible they have a pretty good chunk of iron that bolts to the crankshaft the flex plate is a separate piece attached by the same bolts. I don't think it is enough mass to satisfy the needs of this diesel. The rest of the mass is the torque converter. I would vote not to do it.

 

You guys are always trying to talk someone out of doing something.

There's plenty of videos/information on people starting Cat engines and Cummins/whatever else on the ground or on an engine stand without a transmission.

I probably won't ever build a 7.3 home generator.. but good to know you guys think that's not a good idea.

 

That would be because there are some things that can't be undone or repaired.

 

Unless the transmission has something to do with the balance of the motor I don't see how it's absence would have any effect on running the motor. Properly secure the motor bell housing to the engine stand, and it won't know there is anything different aside from "oh, hey this is really easy."

That said, I don't know how the computer and the transmission talk with the diesel. You may run into a problem there.

 

It doesn't affect the balance of the engine. It does affect the rotating mass, so it may not idle very well.

A flex plate has very little mass. A manual trans flywheel has a lot of mass. The torque converter bolted to the flex plate gets the mass of the system approximately the same as the manual trans system.

The only interaction that will affect this is the range sensor will need to be plugged in and in park or neutral, or you could work out a jumper to bypass that.

 

Don't forget, the cooling aspect of it as well.

In order for the engine to get up to operating temp the thin the oil like driving conditions you will want it to run long enough for the thermostat to open an close at least twice.

Other wise you would be completely wasting your time even starting the engine other than looking for a gross leak as if a gasket was completely missing

 

Yes, and those engines almost always have a huge flywheel bolted to the crankshaft. He has an 7.3 Powerstroke with an automatic transmission. Automatic vehicles use the torque converter as a flywheel. The flexplate is a fraction of the necessary weight for the engine.

@0500757Arf, the engine will start and run with just the flexplate attached, but it may not run for very long without stalling. If it does run, it's likely the idle will be very erratic.

We ran a Lexus V8 with just a flexplate, and it really struggled to hold any kind of smooth idle, and would sometimes stall on quick throttle snaps...and that was just a small 4.0L V8, not a big diesel running 18:1 compression.

 

hmm.. didn't know that. New question.. If in fact I bolted a flywheel and not a flex plate to a torque converter.. could this be the reason the car never wants to go over 45mph? Or was that $75 Ford wagon full of beer just doomed from the start haha?