Broken teeth flex plate

[98Bacon]

So I have a 98 k1500 5.7 with 315K on it. I've had the truck for a couple of years and it has always run good and reliable. Yesterday I tried to move it to begin oil change and coolant flush. When I tried to start it a horrible clanking noise came from the starter so pulled it off and inspected to find damage on the teeth of the starter. I figured the selinoid was shot so I put another starter on it and it made a similar noise (not nearly as bad) and the truck started and ran poorly. I let it run in the driveway and it began to throw codes (random/multiple cylinder misfire and cylinder 4 misfire). At this point I discovered that the distributor cap was broken around the bolt tab and loose. I decided to go back under the truck and put the heat shield onto the starter and while I was down there I looked through the peep on the bell housing (didn't know it was there) and discovered chipped and broken teeth on the flex plate. WTF?? I'm wondering if anyone would have any insight as to why any of this happened and are these issues related? Thanks

 

[Schurkey]

Bad teeth on the starter drive will create bad teeth on the flywheel/flexplate ring gear. And the other way around.

Wear on the flywheel/flexplate will concentrate in four areas--due to the four planes of the crankshaft on a V-8 engine. This may or may not also correlate to the distributor problems listed.

You run the new starter on a failed ring gear, you'll ruin the new starter drive.

There are two choices: Replace the ring gear/flexplate before the starter gets damaged, or replace both later on.

 

[skylark]

Distributor problems can result in a misfire while cranking and cause teeth to chip and break off of a flexplate.

 

[98Bacon]

The starter was put in last fall (New AC Delco) and it just seems like more than coincidence that both issues showed up on the same day with a good running truck. I'm a wannabe diy mechanic so I will replace the cap and rotor but the flex plate replacement is out of my league, what should I expect for replacement cost approximately?

 

[Gramps]

If you attempt yourself, the flexplate is around $50 new. But requires the trans to be disconnected and pulled back at least a few inches for you to have access to the flexplate bolts.

 

[CrustyJunker]

Also was a victim of this years ago. Defective distributor cap was crossfiring, caused the engine to backfire while cranking and knocked off a few teeth on my flexplate/damaged the starter. I eventually changed my flexplate out for a heavier duty one. Never broke flexplate teeth again.

The bad cap thing happened again to that truck twice more over the years (moisture issues those times)...But it just ruined a couple more starters instead (much easier to change).

 

[HotWheelsBurban]

Nice to know I'm not the only one this happened to! 4 years ago I had to have the flywheel replaced on my 99 vortec 5.7 Burb, after it blew up the end of the starter. Now l think l have to replace the starter l replaced then, or it may be another problem. Fun with trucks in the rain tomorrow....at least I will be under it

 

[Schurkey]

"Good luck" getting an aftermarket flexplate to have the same balance as the OEM flexplate.

I bought a Vortec short-block from a Treasure Yard. It got pulled for a "rod knock" that turned out to be a cracked flexplate--the crank and bearings were fine.

I bought two flexplates, and neither one had a visually-identical balance weight welded to it. Took them both to the balance shop, one was ~40 grams light, the other was ~30 grams heavy. The guy drilled the heavy one, and added weld to the light one.

 

[rags77]

What size flexplate bolts...that goes to crank shaft..16 or 15s

 

[Schurkey]

What size flexplate bolts...that goes to crank shaft..16 or 15s

Huh? "16 or 15s" doesn't make any sense.