broken pump rotor
04-11-2010, 04:47 PM
#1
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broken pump rotor ok, 4l60e guys, what do you think happened?
pulled the trans for a rebuild-the 2-4 band was slipping. replaced the band, reverse input housing, all clutches and steels. already had a trans-go shift kit. had ecm tuned for firmer shifts. installed ebay stall converter.
about 1500 miles later, sitting in the drivethrough i heard a fast tapping noise, then lost all gears.
pulled the trans and found both pump rotor teeth broken. luckily the cover was not scored and it was a clean break, there is nothing in the filter and all pieces of the rotor are accounted for. what happened?
first i checked to see how far the hub notches engaged the rotor teeth-
they went about 2/3 into the hub and same on the teeth. so it wasnt putting force on the teeth, but was it not engaged far enough?
i checked the stock converter and it looks about the same.
second i checked crankshaft end play, not a problem.
if the converter slid out during install, wouldnt it have broken on startup, or when bolting the bellhousing on?
the only thing i can think of is too high line pressure? warped flexplate? can the t/conv be at fault? i really dont want to re-use it if it cound have been the converter. this pump has 132k miles on it, and had no problem before (at stock line pressures) so there must be a reason it broke.
pulled the trans for a rebuild-the 2-4 band was slipping. replaced the band, reverse input housing, all clutches and steels. already had a trans-go shift kit. had ecm tuned for firmer shifts. installed ebay stall converter.
about 1500 miles later, sitting in the drivethrough i heard a fast tapping noise, then lost all gears.
pulled the trans and found both pump rotor teeth broken. luckily the cover was not scored and it was a clean break, there is nothing in the filter and all pieces of the rotor are accounted for. what happened?
first i checked to see how far the hub notches engaged the rotor teeth-
they went about 2/3 into the hub and same on the teeth. so it wasnt putting force on the teeth, but was it not engaged far enough?
i checked the stock converter and it looks about the same.
second i checked crankshaft end play, not a problem.
if the converter slid out during install, wouldnt it have broken on startup, or when bolting the bellhousing on?
the only thing i can think of is too high line pressure? warped flexplate? can the t/conv be at fault? i really dont want to re-use it if it cound have been the converter. this pump has 132k miles on it, and had no problem before (at stock line pressures) so there must be a reason it broke.
04-11-2010, 05:13 PM
#2
look for slide marks on the gears where they were on top of the and slipped off that will tell you if the converter was miss installed. Also check your converter to flex plate clearance when reinstalling the trans and converter should be between 1/8 and 3/16 inch from conveter bolt pad to flex plate with converter completely slide back into the trans.
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Last edited by performabuilt; 04-11-2010 at 11:09 PM.
04-15-2010, 03:53 PM
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I broke my pump rotor 4 times before I went billet and had the torque converter hub replaced. So far no problems. I was asking all of these questions when it broke last time, but in the end we have no idea why it broke. The billet rotor is a lot more money than the cast one, but it is WELL worth it.
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04-21-2010, 09:35 AM
#8
I broke 2 rotors last year and am currently having transmission issues again. I went with a billet rotor after the 2nd failure. If you can manage to pinpoint why it broke, please post up here 
My first one broke after over a year and 300+ passes at the track and it's still a complete mystery to me.
My first one broke after over a year and 300+ passes at the track and it's still a complete mystery to me. 
04-22-2010, 08:46 PM
#10
Was the pocket depth of the pump body matched to the right slide and rotor? There are few different thicknesses.
What brand was the slide and rotor? I've never had good luck with anything but original AC Delco.
Other then that, converter depth and balance could cause it also.
What brand was the slide and rotor? I've never had good luck with anything but original AC Delco.
Other then that, converter depth and balance could cause it also.
