: Tranny Prob, sheared pump shaft



Canuck97
11-13-06, 10:02 PM
I posted a similar thread in the Eldo/Seville forum by accident, and got no responses, so maybe some insight from the technically inclined....

Had a P1810 code on a 97 STS that wouldn't engage in any gear. Dropped the engine/transaxel out the bottom and removed the side cover and pump assembly. To my delight, I've found the problem... a sheared "oil pump driven shaft" (#2 for those with the manuals....). The shaft is approx 8 inches long and has "allen" type ends. It sheared deep on the TC side.

I can see the piece still there, and have tried repeatedly to "fish" it out with a magnent, but no luck yet. So before I spend a few more hours on this I just wanted to make sure it is doable to pull the end of the shaft out from the pump side of the tranny (ie, without pulling the tranny off the engine.

Input?

Canuck97
11-14-06, 10:21 PM
OK, i got to thinkin, my daughter said the steering wheel got 'hard to turn' at the light she was stopped at just prior to the tranny failing. Hmmm.... sounded like something loaded the engine up and reduced the idle RPM.....sure enough, took the pump apart and a few teeth were ripped off the gear between the primary and secondary pump. Anybody got a good place to get new pump gears for a 4T80E?

dkozloski
11-14-06, 10:58 PM
OK, i got to thinkin, my daughter said the steering wheel got 'hard to turn' at the light she was stopped at just prior to the tranny failing. Hmmm.... sounded like something loaded the engine up and reduced the idle RPM.....sure enough, took the pump apart and a few teeth were ripped off the gear between the primary and secondary pump. Anybody got a good place to get new pump gears for a 4T80E?
What are you going to do about the debris in the system downstream from the pump?

Canuck97
11-15-06, 12:56 PM
DK,
First a little clarrification, it's actually the gear between the two scavenge pump gears that lost a tooth and a half. The two main pumps actually look good. I've taken the upper valve body apart, and no FOD. I also found the tooth (plus the half tooth) in the scavenge pump. Hopefully this means no big pieces downstream, and the upper reservoir magnent has a decent amount of "fur" on it so hopefully most of the shavings are accounted for. With 160K miles on the car, I think I'll reassemble it in hopes of getting another 40K out of the tranny, and if it doesn't work out, I'll probably be better served replacing both the engine and tranny as a unit from a low mileage salvage ($2000-2500). I'm hesitant to put $1500 into rebuilding the tranny to just turn around and have to replace the engine in a year

chevelle
11-17-06, 03:05 PM
That is REALLY an odd failure for a 4T80E.

The scavenge pump you describe just pumps the oil from the bottom pan to the side cover so any debris isn't likely to go much further since the actual line pressure pump (with the variable vanes) is filtered on the inlet from the side cover. The question is why the scavenge pump shed a gear.....???? I must have picked up some debris from the bottom pan or something? Have you had the bottom pan off yet to check the pickup screens and/or pan for other debris. There may have been another failure that precipitated the scavenge pump failure.....

Canuck97
11-27-06, 12:38 PM
Chevelle,
I've had the bottom pan off and the the upper valve body apart. No fod other than the stuff in the scavenge pump itself. It looks to me like the middle gear just wore down to a point over the years that it was very weak, then shed a tooth which caused a chain reaction. The dealer gave me all three gears for under $30, so all that's left to do is put the side cover on, raise the transaxle/engine and start 'er up.