97 5.7 stalls/stops on starter crank, advice?

[TuckerK]

97 Suburban 5.7. When starting, engine turns over normally, but every 2 seconds or so the motor will completely and suddenly stop rotating for a split second, then start cranking again. It is as if every few seconds there is a buildup of compression in a cylinder that won't allow it to turn over. It will eventually start and run normally, but i believe this has contributed to going through 3 starters within 20k miles. The starters are free (warranty) but getting tired of putting them in. Any suggestions would be welcome.

-Tucker

[rhandwor]

Originally Posted by TuckerK

97 Suburban 5.7. When starting, engine turns over normally, but every 2 seconds or so the motor will completely and suddenly stop rotating for a split second, then start cranking again. It is as if every few seconds there is a buildup of compression in a cylinder that won't allow it to turn over. It will eventually start and run normally, but i believe this has contributed to going through 3 starters within 20k miles. The starters are free (warranty) but getting tired of putting them in. Any suggestions would be welcome.

-Tucker

Mark the zero mark on the timing bracket then hi light the timing mark on the harmonic balancer. Turn the engine over by hand counterclockwise stop at the zero mark. Remove the distributor cap and mark the tip of the rotor and the side of the distributor. Rotate the engine counterclockwise until the rotor starts to move stop. If over 20 degrees your timing chain is stretched.

[j cAT]

Originally Posted by TuckerK

97 Suburban 5.7. When starting, engine turns over normally, but every 2 seconds or so the motor will completely and suddenly stop rotating for a split second, then start cranking again. It is as if every few seconds there is a buildup of compression in a cylinder that won't allow it to turn over. It will eventually start and run normally, but i believe this has contributed to going through 3 starters within 20k miles. The starters are free (warranty) but getting tired of putting them in. Any suggestions would be welcome.

-Tucker

if the engine runs normal then the issue is with the starter mounting. these starters [rebuilt ] most times require shims. did you check for the clearance between the fly wheel teeth and the starter gear shaft .

If too close the starter will bind on the flywheel. also this destroys the drive bearing.

[TuckerK]

Thanks guys. I first suspected the starter as well, however I pulled the electronics and cranked it and it did fine, so it is obviously a timing issue. I was ready to test the timing chain as described, but when I pulled the cap, I noticed that it was so worn, some of the contacts had developed little side "slag" bumps on them on the leading side. I now suspect that those are causing an jump/short that causes a BTDC fire intermittently. I will replace the cap, rotor, plus etc... and see if that was the issue.

Thanks for the advice, will keep you posted.

-Tucker

[TuckerK]

It was the distributor/rotor. The little slag stalagmites that built up on the electrodes cause it to intermittently short, sending a spark far BTDC, stalling the motor. New cap and rotor fixed it.

[rhandwor]

I'm glad you found the problem.

[j cAT]

Originally Posted by TuckerK

It was the distributor/rotor. The little slag stalagmites that built up on the electrodes cause it to intermittently short, sending a spark far BTDC, stalling the motor. New cap and rotor fixed it.

after a few thousand miles check the rotor/cap. if it is messed up again check that the distributor bearing is not worn , rotor wobble.