have a 84 chevy k5 blazer that previously had an aftermarket starter that grinded no matter how many shims i used,i replaced it with a stock starter and for about a week it didnt grind at all,then it started to grind so i put a .40 shim in it and it was fine for about a day then it started grinding,so i took the shim out and it is fine again????i am mechanically inclined but i dont understand why its doing this,the flywheel is in ok condition,not bad enough to cause problems..Ideas?

 

Are the bolts staying tight? Can the starter move at all side to side (twist)? How did you determine that you should use 0.040" shims (I assume you left off the first zero because 0.4" is A LOT).

 

yeah its 0.040 and no i doesnt move at all,i dont understand it at all,and i dont have time to keep shimming and un-shimming my starter either which is weird,and i determined i used 0.040 because thats what it says on the shims i purchased and im assuming thats the thickness.

 

Have you rotated the flex plate around and inspected the gears all the way around? As well as checked the clearance all the way around? It is possible that there are some really damaged gears and/or that the flex plate is bent opening up or closing up the clearances depending on where the engine stops.

 

it could possibly be bent but that wouldnt explain why for a week with a brand new starter it was fine and then i shim it and its fine for awhile and when i take the shim out its fine again..because once it starts grinding again,it doesnt stop it will grind every time i turn the key untill i fix it.

 

Luck of the draw? I had a 3" section of teeth out on the flex plate in my Chevelle. It went fine for a long while before it hit that section and the starter just spun. That car started up without going through 1 revolution of the crankshaft as I suspect yours probably is as well.

 

every time i shim and un-shim the starter i have looked at the flywheel and i have seen no bad sections,and unless my truck is warm it takes about 10 seconds of cranking before it starts,and usually it grinds real bad for about 5 of those seconds then it will get a little better.

 

Something isn't right in there. No use speculating until you have verified that the flywheel is straight, round, and has all its teeth.