Slipping Tranny

I have a '96 SC Riv that I bought with 99k on it. It now has 104k. In the last week, there's been two incidences of severe slippage. My girlfriend told me she had a problem with it slipping and when I drove it the next day (and for the next few days) it was perfectly normal. Today I ran out to do some errands at lunch and after stopping at a stop sign, it suddenly started slipping like mad. Once I got it going it seemed to be ok, but every time from a stop, lots of slippage. It seemed that if I pulled it down into low and upshifted manually it was somewhat improved. Reverse is as normal, no change.

I did check the fluid level after she reported the problem and the level is fine. The fluid isn't fresh pink, but it doesn't smell totally fried. As I bought the car at 99k I have no idea is it was ever serviced. It might very well be the factory fluid in there.

I would think that once it started to slip from wear, it would just keep on slipping. But as it slips one time, then acts perfectly fine for the next few days is it more likely I'm experienced some problem in the valve body where it's hanging up on a check valve or something intermittently? Maybe wishful thinking?

Update:

Slipping again on the way home. Fluid smells worse today, so no more driving this car! On the highway setting the cruise the converter locked up fine and held a steady 1500 RPM's at 60 MPH.

It's almost impossible to detect shifts and starting out in drive it flashes to at least 3,000 RPM's just to get it rolling!

Get that fluid changed asap, Ken. May not solve your problem, but it might help. If it does, I'd change the fluid again soon, to get all the old out. You're probably right thinking it's never been changed. Good luck with this.

Thanks for the response, AA. That car will not be driven until the fluid is changed! I'm also very curious to see what's in the bottom of the pan.

AA wrote:

You're probably right thinking it's never been changed. Good luck with this.

lol, he should look at the SC oil too. if the tranny aint been serviced, I guarantee the SC hasn't been.

dreww wrote:

AA wrote:

You're probably right thinking it's never been changed. Good luck with this.

lol, he should look at the SC oil too. if the tranny aint been serviced, I guarantee the SC hasn't been.

Your probably right! I have the SC oil from the stealership. I'm looking forward to offering $5 to anyone that will take a good long sniff of the old stuff!

Heck Ken, it isn't THAT bad!

Luckily, the M90 will survive longer without proper maintenance. Change the oil, but you're probably okay.

1998 Riv wrote:

Heck Ken, it isn't THAT bad!

Dave-

I thought I read on here that it smelled like "condensed gorilla ass juice".

71gsx455-4spd wrote:

1998 Riv wrote:

Heck Ken, it isn't THAT bad!

Dave-

I thought I read on here that it smelled like "condensed gorilla ass juice".

Yeah, it's pretty nasty, just do whatever you need to do to prevent spilling it in the engine bay or on yourself. And make sure the SC is stone cold before removing the plug.

www.tripleedgeperformance.com/4T65E_Transmission_Info.php

Nice site, good info. I wonder tho if all that info applies to us 95 and 96 4T60E's?

What you are describing happened to me on two different '98s. Pulling it into 1st helps out. The problem both times was the PCS (pressure control solenoid).

Gotta stay on top of fluid changes in these things.

Derek-

Did you change out the solenoid? If so, did you do it yourself and how difficult was it? Can it b done with the tranny in the car?

I had a trans shop do it. Unfortunately in both cases we let it slip for so long (months) it ruined the clutches and they had to do a full rebuild. They said it could have been saved by fixing the solenoid early.

Shifting into 1st boosts the fluid pressure by a whole lot and covers the problem. Unfortunately pressure is still out of sorts and the lowered pressure will eventually do other damage (even though everything still seems to work).

I may be in luck (Maybe). I've got the 4T60E in my '96 Riv and it has an external vacuum modulator (no internal pressure solenoid). One bolt and it comes right out. Think I'll pick one up and give it a shot!

Well, as an update, I dropped the pan and did a filter and fluid change. The pan had some dark silt like stuff in the bottom in a pretty light film. No pieces of transmission. The fluid was shot, but it was probably the factory fluid. I also put a new vacuum modulator on it.

Net result? It's the same! Still slipping! (I wasn't that surprised, really)

I did notice the with the pan off there are three tubes that go into a manifold. The innermost tube, which also has a piece of rubber line spliced in the middle, was loose in this manifold. I did manage to push it back in, but the whole thing being loose bothered me. Anyone else ever see this?

I recall mine was like this. The tranny shop that rebuilt mine said they see it all the time and it wasn't a big deal as the filter holds it up, but they wired it to one of the other tubes to hold it in place anyway (common practice for them).

Hi Guys,
The line with the rubber hose is for lube oil to the differential. They do fit loose but it isn't critical because the lube is under high volume but low presure, just enough to keep the differential gears and bearings splash lubricated.
The transmission slipping in first only would likely be the forward band or low roller clutch. The Input clutch and sprag are probably OK because they are applied in reverse as well and reverse seems solid, right?
Another thing that this vintage of hydramatic did was to have a 2-3 shuttle valve stick in the valve body, but that usually felt like loss of engagement after a deceleration.
HTH
Tim McCluskey

tim63riv that is a heckuva 3rd post

tim63riv wrote:

The transmission slipping in first only would likely be the forward band or low roller clutch. The Input clutch and sprag are probably OK because they are applied in reverse as well and reverse seems solid, right?
Another thing that this vintage of hydramatic did was to have a 2-3 shuttle valve stick in the valve body, but that usually felt like loss of engagement after a deceleration.
HTH
Tim McCluskey

Thanks for the input Tim. Yes, reverse is solid. No problems. The way this transmission "gave notice" was just after a deceleration. I came to a stop sign an when I went to move forward, the slip was instantaneous. Could I have a sticking 2-3 shuttle valve, as you suggest? And if so, how would I go about repairing this problem? New valve body?

Thanks again!

Ken,
One way to try to free up any sticking valves in the 4T60-E is to disconnect the vacuum line from the modulator and plug the end coming from the engine so that there is no vacuum leak. By doing this, you "trick" the transmission into suppling full line pressure internally. This increase in line presure will cause harsh shifts, but that is what you are looking for. When the valves get hit with higher than normal pressure, they move faster and with much more force than normal. The speed and force of the valve movement can dislodge debris from the valve bore and flush it into the pan where the magnet or filter can trap it. (Side note here, NEVER remove the transmission magnet, it is there to keep steel and cast iron particles out of your transmission, especially the valve body! I know they can look nasty on a filter change, but clean them up the best you can and put it back in! Hydramatic put it there for a reason!)
Another possiblity is an issue with a shift solenoid. There are two shift solenoids used in the 4T60-E the 1-2 ("A" solenoid) and the 2-3 ("B" solenoid) When the solenoid is energized, i.e. turned on, it holds pressure, when it is de-energized, turned off, it releases pressure. Below is the normal shift solenoid status:
1st gear 1-2 on, 2-3 on, both holding pressure
2nd gear 1-2 off, 2-3 on, 1-2 releasing pressure, 2-3 holding pressure
3rd gear 1-2 off, 2-3 off, both releasing pressure
4th gear 1-2 on, 2-3 off, 1-2 holding pressure, 2-3 releasing pressure
Now let's say that your 2-3 solenoid has a piece of debris floating around that gets stuck in the solenoid occasionally, causing it to release pressure. So the ECM commands 1st gear as you come to a stop. As you go to accelerate, the shift solenoid status that is commanded is 1-2 on, 2-3 on, but hydralically the 2-3 is releasing pressure which is the same as 4th gear! The owner complaint is "slips" on acceleration when actually the the car is accelerating slowly because of it being in 4th gear!
Now if your car has burnt fluid, the damage may already be done. What the ideas that I shared do for you is give a somewhat better understanding of what oes on inside the 4T60-E. Disconnecting and plugging the vacuum modulator costs nothing, so it would be worth a try.
Good Luck and keep me posted!
Tim

OK, this is an old thread but I finally got the tranny scanned. It's throwing a P0758A code which I understand is the 2-3 shift solenoid. Is this solenoid accessible with the pan dropped? Or is it buried behind the side cover? In other words, easy fix or monumental task?

Thanks!

your tranny was doing the same thing mine was.... i just replaced mine today..hopefully its something easier for you man....good luck

To get at any soleniods you must drop the trans. Unfortunately the side cover is much deeper than the room in the engine bay will allow.

my transmission seems to be slipping very bad .It will go into reverse but slips and at high rpm.it will go forward but seems like only one gear,or "limp mode".but when I first drove the car it shifted fine for about 20 miles.i've looked for any solenoids,but cant find any, the trans lines go straight inside the tranny would the PCS be inside the trans or underneth somewheres?