Transmission acting strange under any acceleration from 0 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 04-25-2008, 03:11 AM   #1
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Default Transmission acting strange under any acceleration from 0

1999 SLE
134.4K miles
OE transmission, but flushed every 30K miles

Twice now when I've been in the car, and not consecutively, the car felt like it neutral-dropped to D two times each time. Here'* a giant paragraph to clarify this.

Both times the car was relatively warmed up after about a half an hour or less of sitting in 80+ degree weather. Each time, the transmission seemingly neutral-dropped to D twice before smoothly driving and shifting just fine. The two times when it did that weren't one after the other, but both were just today. Basically, I put the car from P to D and let off the brake, tried tapping the gas, and the car instead of moving did that before then moving.

I'm planning to use Seafoam Trans Tune for about 100 miles before getting a flush. I'd like to drop the pan, replace the filter, fill it up, and then take it to some place to get a flush. Is this the best way to go about it? I'm anticipating a trans filter question. I haven't changed it, and I'm not sure about the two previous owners.
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Old 04-25-2008, 11:06 AM   #2
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Default Maf

If your gutted air box has an aftermarket high flow oiled filter, take your MAF out and clean it.
There is a GM service bulletin on this for oils contaminating the Maf causing slippage. I'll try and look for the #.
Edit:
Its SB 04-07-03-013
Transmission slippage and damaged clutches. Oils contaminate the MAF and GPS signal may be low.
The file is in PDF format
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Old 04-25-2008, 12:30 PM   #3
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Sounds like you are describing the "bang" start:

Quote:
Neutrals at stops, Shudders on take off: One of the most common problems I have found after the milege gets over roughly 60K miles. The scenario.... You are driving in traffic for a while OR your car has sat for a while and is a cold startup. You put the car in Drive range and it wont move, or if driving you come up to a stop light and in heavy traffic and the light turns green and SUPRISE!!! You are holding up traffic with a car that wont go anywhere. The most common cause of this problem is a worn out inner surface of the Input clutch piston. I will post pics soon so you can better understand why it IS a real problem. Once the inner sealing area wears it can prevent the inner lip seal for the piston from sealing properly. You may find that revving th engine up will finally get the car to move and it will BANG into gear. This is because the pump in the transmission is working harder and moving more fluid thus allowing the added fluid to overcome the leak which prevented the clutch from either initially applying or staying applied. Another area of concern that causes this is a boost valve in the valve body, not near as common but it can cause this problem on a lessor scale. If a fluid/filter service has not been performed in a very long time then a very dirty or plugged up filter can add to problems as it because a major restriction. IF the filter is found to be very dirty on the inside, which can be verified by cutting open the filter, then there are other problems inside the transmission anyways and an overhaul is the only correct way to fix the problem.
(Above excerpted from: http://www.tripleedgeperformance.com...ssion_Info.php)

Another contributor to the bang start is GM'* known poorly designed 4T65E input clutch piston inner lip seal, corrected in aftermarket overhaul kits:
http://www.transtec.com/transtec_bulletin/tb9916.pdf

Both my 1998 and 2004 LeSabres do this "bang" start every now and then. The 2004 (at ~60k miles) maybe once every 2 or 3 months; the 1998 did it that often at 40k miles; now at 105k miles it does it once or twice a week.

All this said, the first thing to do is, as you guessed, pull the filter and cut it open (inspect for metal shavings/particles, etc; just routine exploratory measure, really). If the filter'* really gunked up and causing a restriction, maybe that'* all you need.

I did find that the additive LubeGard Red (entire 10oz bottle in the trans) seemed to "slow" the progression of this problem on the 1998, maybe due to either increased viscosity or swelling the seal? I've also heard that the new Dexron VI is higher viscosity than Dex III, so maybe that could help?

Good luck.
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Old 04-25-2008, 12:48 PM   #4
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Is this the part you're talking about?
http://intense-racing.com/Merchant2/...ategory_Code=T

Sorry to butt in here, but I'm having the exact same problem some times with my new-ish transmission.... Is it easy to replace? Do you have to drop the transmission to get to it, or can you just go through the fluid pan?
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Old 04-25-2008, 01:04 PM   #5
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No you won't be able to change that without dropping the trani and pulling it apart. :(
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Old 04-25-2008, 01:06 PM   #6
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petra,

That input piston is part of it; the inner seal I mentioned rests between the input clutch hub and the inner radius of that piston. The OEM inner seal has too small a lip to begin with, and with time the inner bore of the input piston wears; and voila, in an aged 4T65E it takes extra pump pressure to pressurize the input clutch piston. (Thus the "bang" start...and extra wear on the pump shaft, too, I'm coming to believe while researching this)

You cannot get to this through the pan. You have to remove the side cover, internal harness, pump, valvebody, case cover, 4th clutches, gearset/chains, driven sprocket support/4th clutch piston housing, and 2nd clutch housing before you can get to the input/3rd clutch assembly. You then have to completely disassemble the input/3rd clutch assembly to get to this piston and seal.

(I'm dismantling a 4T65E-HD right now, so this all first-hand)

Where'd you get your new-ish trans? Was it rebuilt? If so, which seal kit was used? (TransTec is the only brand I know of that acknowledges this issue with the input clutch piston inner lip seal)

EDIT: Bullet posted while I was being long-winded
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Old 04-25-2008, 02:38 PM   #7
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Holy moly, that'* a lot of information! I read it all, but I'm not sure about how to respond. The gutted airbox has a dry paper filter. Should be a Purolator or so. Speaking of which, I should probably replace it now anyway.

It was mentioned that some red stuff slows the progression of this problem. This worries me because of the word "progression." Does this mean the problem will worsen and eventually cause a failure? What'* the average mileage after the beginning of the problem? Is what I described a textbook shudder start issue?

Thank you all for your replies. I assure you I'll keep reading intensely, so you guys just keep posting. Due to us doing "stuff" mainly on the weekends, I won't feel comfortable putting in Seafoam Trans Tune just yet.

And lastly, I drove the car some more and did not experience the shuddering takeoff. Whoo! I'll keep you updated.
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Old 04-25-2008, 03:19 PM   #8
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Quote:
Originally Posted by radomirthegreat
It was mentioned that some red stuff slows the progression of this problem. This worries me because of the word "progression." Does this mean the problem will worsen and eventually cause a failure? What'* the average mileage after the beginning of the problem? Is what I described a textbook shudder start issue?
What you described sounds like the textbook "bang start."

I'll tell you what i mean by "progression." A few months after we bought the 1998 in 2001 (at 36k miles), it started doing this maybe 1 or 2 times a month. Within a year, it was weekly. There was a TSB on this that involved getting a PCM reprogram at the dealership (I suspect they upped line pressure); we did that in like 2003 at just under 60k miles. This took it back to happening once a month. After another maybe year and a half, by maybe 75-80k miles, it got back to weekly. That'* when I put in the LubeGard. That stopped it completely for about a year. Then it went back to monthly for a year. I upped line pressure again with the tuner almost a year ago (at say 95k miles). It went away again for 6 months. Then it was monthly for 3 months. Then weekly for 3 months. Now it'* getting to almost daily, and that'* why I'm rebuilding a spare tranny

The 2004 (about 60k miles) is at every 2 or 3 months currently. I intend to feed it some LubeGard soon and see what it does for that one.

So, to make a long rambling short, perhaps an additive will buy you a year, give or take. Upping line pressure may help, too...although I suspect that could lead to better operation now at the expense of full seal failure sooner.

So, how long you keeping this car? (Or more accurately, this trans?)
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Old 04-25-2008, 03:20 PM   #9
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Quote:
Originally Posted by agrazela
Where'd you get your new-ish trans? Was it rebuilt? If so, which seal kit was used? (TransTec is the only brand I know of that acknowledges this issue with the input clutch piston inner lip seal)
Sorry to steal your post, Radomir, if the mods would like to split this, that would be OK.

The tranny wasn't rebuilt. It'* a 2003 OEM with around 60k miles on it now...
And to tell you the truth, it'* only happened to me only about two or three times, but that was a few months ago and they happened around the same time, so idk...
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Old 04-25-2008, 04:14 PM   #10
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I'm all right with this being "stolen" since it'* still about transmission issues. We can all learn from it, so why not have it all in the same place?

As for how long I'm keeping the car, as long as it takes. I want to have this SLE for a long, long time, or at least until a better deal comes along. I may get the Intense PCM to up the pressure as well as doing a flush and using an additive. Is the red additive still recommended over any other trans additive?
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