Hello all,

I just recently finished building and installing a stroker motor into my 01 XJ, and as the title suggests, it makes an absolutely AWFUL metallic scraping/banging noise while cranking with the starter. My first thought was that the starter wasn't engaging properly, so I swapped it out with a brand new one from NAPA with no results. After pulling the inspection cover to expose the flex plate, it's obvious something is off. Some of the gear teeth on the flex plate already have some decent, abnormal wear. I can visually see chips of the gear teeth falling off into the bellhousing (see photos and video below). This is also a new flex plate that I installed with the new motor and should not show any signs of wear already.

Anyways, I know that this is an issue somewhere between the engagement of the starter & the flex plate. The noise completely disappears after the engine starts and I cannot see any areas where the flex plate may be rubbing on something. Has anyone had this issue before? I no longer want to crank the engine over and further damage my flex plate until I get this figured out. Any help or ideas would be greatly appreciated!

Video Link:

Undamaged flex plate teeth

Worn flex plate teeth. Looks like the starter is only engaging the very edges of the gear teeth.

Shavings from the gear teeth that have fallen into the bellhousing.

 

the biggest clue is you say you installed a new flex plate

its a known issue they can be slightly incorrect dimensions

Hopefully you retained your original, so you can at least attempt to make some comparison measurements

Double check the part number and make of what you ordered, Rock Auto has good info, did you use the factory parts manual ?

I cant think of anything else it could be, 1/16" would be enough, maybe it will just grind itself to a nice "machine matched wear pattern"

 

I appreciate the reply! I've also posted this same issue in the XJ Facebook group and was sent a video where the guy has a warped flexplate ( ). His jeep sounded indetical to mine while starting! I need to do a few more inspections but it's likely I have the same problem. Looks like he had a similar aftermarket flexplate on there as well. If the plate is warped, that would explain why the teeth on the ring gear are only damaged in certain spots.

Unfortunately I chucked the original flexplate. My current one is a pioneer aftermarket from rockauto which I am now reading mixed reviews about. I'm most likely going to go for a good used OEM replacement off ebay next, unless I can find a new one somewhere.