jkbail

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?

89 Rag

What service manual claims "partial sieze" that's sounds a lot like "almost had sex" or "almost pregnant", it would seem to me that the motor is either siezed, or not siezed.

j9fd3s

put a 19mm wrench on the motor and spin it. it should spin easily. if the motor spins freely you need a starter. they can test ok on a bench and be bad under load.



if the motor doesnt spin freely, dont waste your time trying to start it, pull it out and see whats wrong before you ruin it

1988RedT2

^^^ What he said.



And check the wiring to the starter. Engine fires can surely melt insulation and cause a short.

mazdaspeed7

Ive had a problem where the motor was difficult to turn over. It turned out to be a spun bearing(2 seperate times), and one of the times, the thrust bearings failed as well, basically destroying the stat gear and everything up to the front counterweight.



For the people who cant read, the starter was tested and rebuilt already.



The stat gears and main bearings can be replaced with the engine intact, if it is in fact a spun bearing. The front can be done with the engine in the car, but to get to the rear, you will have to drop the tranny or pull the engine. To get to the front one, you need to pull the front cover and remove everything from the eccentric shaft. Another possibility is a crushed thrust bearing, which could be anywhere from bad to very bad. If that is the case, it will be very obvious when you get to the thrust bearings.

j9fd3s

color me biased but unless its a mazda rebuilt, i still think its the starter. the parts store rebuilds can last hours sometimes, theres no quality control.

jkbail

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. 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)?

mazdaspeed7

Fair enough









Pull the belts, leave the spark plugs in for now. Try to rotate the engine by hand. If its still tight, pull the spark plugs, repeat. If its still tight, you have a problem. If you have to use a ratchet on the main pulley bolt to turn the engine over, you have a problem.

j9fd3s

yep.