4L80E GM Transmission/ fluid replace or use the old??


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Old 03-04-11, 05:50 AM
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4L80E GM Transmission/ fluid replace or use the old??

1991 Chevy needs new transmission internal/external wiring harness. OK I can do that. Question is that some "experts" have advised to reuse the old transmission fluid. Theory is that using new transmission fluid with its detergent action will exacerbate other problems lurking in the 150,000 mile transmission. I have changed the transmission fluid only once in 150,000 miles/me bad.

Soooooooooooo, please advise to change or not to change????

Its all fun.

Rebel
 
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Old 03-04-11, 07:56 AM
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Change it. We've gone round and round on this question several times. If you do a forum search you'll find one fairly recently with all the pertinent arguments. Bottom line, if the sludge is all that's holding it together and the fresh fluid frees is up, it wasn't long for this world in the first place.

FWIW, you have the same tranny that's in my wrecker; it's only on it's third tranny @ 590,000 miles. I expect to get 250,000 miles at least on the current unit, but I'm a stickler for fluid & filter changes.
 
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Old 03-05-11, 12:43 AM
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The Tow Guy: Transmission was not shifting and set code "VSS Circuit". I changed the VSS solenoids. Sporadically, the transmission would not shift until it hit a bump in the road, then, it would shift. ATF was leaking at the harness connector.

Thanx for the reply I will replace the harness and the ATF and keep on truckin'.

It all fun.

Thanx,
Rebel
 
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Old 03-05-11, 12:52 AM
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Change the filter while you're at it.
 
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Old 03-05-11, 04:46 AM
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Right, should have said that, too; for me that's automatic.
 
 

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