I just acquired an 87 GXL that had a small engine fire. I was told the motor was just rebuilt 20,000 miles ago. Engine was ported and polished S5 main block with S4 intake. The fire only took out wiring harness and a few vacuum/fuel lines. Everything has been replaced.

My problem occurs while trying to start the engine. The engine turns over really slow. I've checked the grounds and battery terminals. The starter has been removed, rebuilt and tested. I attached jumper cables to my truck with it running to make sure that there was adequate power to starter. In my repair manual it claims if the engine is "partially seized" it will make the engine turn over slowly. When trying to start the engine it draws so much power that the coils won’t even produce a spark. The entire ignition system has been tested and within spec. It also creates a noticeable strain on my truck’s charging system.

Is there anything else I should try before making this assumption? What would make the engine partially seize?

If the motor is in fact seized, is it possible to free motor up and get it running again? Is it something an average home mechanic can accomplish? How long would it take?

 

Have you tried push starting it?

 

What about an electrical short somewhere? You said it was on fire right? was it from the PD?

 

To confirm it isn't electrical, try this.

Put it in nuetral, and take off all the pullys. Try and crank it by hand, you should be able to do so, easily. If it takes a shitload of force to turn it, then your engine has some serious internal issues I would think...

 

could be an accessory with a bad bearing, do as Blackplague said and remove the belts and spin each as well as the eccentric shaft, the eccentric shaft should rotate fairly easily with a ratchet, the accessories should all spin freely just by spinning them by hand.

 

So here's what else I've tried thus far. I bypassed all electrical to starter by using jumper cables attached to my truck. Tried to turn the motor by hand but with all belts still attached. Engine rotates easily until it gets to a certain point. Feels like its either getting caught up on something or like it building compresion while I turn it. It will still wants to turn but creates a lot of backwards recoil. I'll next try to loosen all belts and pull the plugs, then try to rotate by hand again.

If worse comes to worse I have a complete S4 with leaky apex seals. Would it be better to rebuild the S4, or stick with rebuilding the ported S5? Can I interchange parts except the rotors obviously (bearings and whatnot)?

 

might sound stupid but is your tranny grounded? that caused mine to turn over slow.

 

I've been through a slow-starter situation many a time. In ALL of my cases, it was caused by the brushes in the starter motor. One or two of the four brushes were worn-down too far, and weren't contacting the commutator becasue the copper braid was holding them back. That's the first thing I'd check before I condemn the engine.

Another extremely rare, but possable, scenario could be caused by warped teeth on the ring gear (flywheel/torque converter).

 

lol, I have to ask, but was the car in gear when you tried rotating it by hand?

 

I was thinking the the starter was binding somehow like Black Sunshine said. If the motor spins freely by hand you have to go back to the starter and...........flywheel. You said that you had the starter rebuilt/checked. Who knows how hot it got during the fire and what warped. Or maybe you took the starter from your S5. I am not sure but I heard on this forum that they weren't interchangeable. Just suggestions

 

I am having the same exact problem bro. my caught caught fire from a failed pd like 2-3 weeks ago. however, the fire was small and I put it out fast, it didnt even melt my omp lines. I changed all hoses, fuel lines, vaccuum lines, fuel injectors, and inspected the wiring harness just to be safe. Also, I used the banjo bolt to pug the leaky pd. However, now the car is starting over really slow... I doubt the engine is seized because it is well lubricated, always watch the oil & its level, its still an amber color. Tested two different starters that I have and both are good. Took off all of the belts and spun the pulleys easily by hand. However, I dont know how to manually crank the car....