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The Debate about Overfilling a transmission? Which is true?

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Old 07-13-2005, 08:33 AM
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Originally Posted by LakevilleSSEi
Originally Posted by Rogue
I always put 1/2 quart EXTRA into the trans when filling. The 4t65E has a fluid starvation defect where its possible on a hard left turn for the trans not to have enough fluid where it needs to be. An extra 1/2 quart helps take care of this.
Sounds like what haro had going on at one point. Except I think his problem was with hard right hand turns?
Ummm I think left...remember the curb video? He was making a left when it slipped.
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Old 07-13-2005, 08:53 AM
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Originally Posted by BillBost37
Originally Posted by LakevilleSSEi
Originally Posted by Rogue
I always put 1/2 quart EXTRA into the trans when filling. The 4t65E has a fluid starvation defect where its possible on a hard left turn for the trans not to have enough fluid where it needs to be. An extra 1/2 quart helps take care of this.
Sounds like what haro had going on at one point. Except I think his problem was with hard right hand turns?
Ummm I think left...remember the curb video? He was making a left when it slipped.
yea it was a left hand turn
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Old 07-13-2005, 09:21 AM
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overfilling raises the fluid level to the level of the spinning components in the barrel. When you do that, you form bubbles. These bubbles can do all sorts of bad things, ranging from improper lubrication all the way town to destroying the pump... see, if you get bubbles in a vane type transmission pump, the bubbles cavitate against the pump wall, and can cause the metal to eventually fail...

aside from the other effects of having bubbles moving through your system, that'* considered to be the important one...
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Old 07-13-2005, 11:15 AM
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I just ran a google search on this, and the result is - Nobody has a clue....

Some sites said don't even think it, unless you want to buy your mechanic a new boat. Others said itwas fine. A couple even said it was a good thing.

My assumption - The engineers that designed this transmission are a heck of a lot smarter than me. I gotta trust them that the hashmarks on the dipstick, and the warning in the manual, are there for a reason.....
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Old 07-13-2005, 11:56 AM
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Originally Posted by MOS95B
I just ran a google search on this, and the result is - Nobody has a clue....

Some sites said don't even think it, unless you want to buy your mechanic a new boat. Others said itwas fine. A couple even said it was a good thing.

My assumption - The engineers that designed this transmission are a heck of a lot smarter than me. I gotta trust them that the hashmarks on the dipstick, and the warning in the manual, are there for a reason.....
my above comment is coming from a gm engineer who spent a few years working in transmissions... so you can trust the source overfilling is bad... very bad. How bad depends on how far the fill line is from the lowest point on the rotating components, which is why some people get away with it...
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Old 07-13-2005, 12:18 PM
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I didn't intend to throw doubt on anything pretty much anyone has said thus far in the thread.

My suspicion is that the info I found will vary by manufacturer. Like I said, GM paid what I assume to be pretty smart people probably a lot of money to design, test, and tell me how to use this transmission. I say trust them...
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Old 07-13-2005, 12:52 PM
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Originally Posted by mkaake
Originally Posted by MOS95B
I just ran a google search on this, and the result is - Nobody has a clue....

Some sites said don't even think it, unless you want to buy your mechanic a new boat. Others said itwas fine. A couple even said it was a good thing.

My assumption - The engineers that designed this transmission are a heck of a lot smarter than me. I gotta trust them that the hashmarks on the dipstick, and the warning in the manual, are there for a reason.....
my above comment is coming from a gm engineer who spent a few years working in transmissions... so you can trust the source overfilling is bad... very bad. How bad depends on how far the fill line is from the lowest point on the rotating components, which is why some people get away with it...
I agree...trust the engineer...except maybe Cough fiero cough
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Old 07-13-2005, 01:10 PM
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You can trust the engineer all you want, but I guarantee they did not engineer these transmissions to be autocrossed with and thats where the fluid deficit rears its ugly head most often however I have seen it happen on roads as well. Filling 1/2 quart over has been common practice in my car since I started modding it and with well over stock power and torque ratings my transmission is still holding strong with never a complaint.

I'm not saying its right for every transmission. I'm not saying its the right thing for YOUR transmission. What I AM saying is that from experience, and the advice of others who are pushing these transaxles (and motors) to the extreme limits that this is what they recommend, and so far it has worked in my car with no issues.
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Old 07-13-2005, 02:33 PM
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Rogue...I agree with you. The engineers have done very well for years of reliability and things like that.

Somehow the Fiero came to mind and I thought...what where they thinking...or maybe they weren't..lol
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