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1994 Cutlass Supreme Convertible 4T60E issues


Nas Escobar

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Well, I guess if it's not one thing it's another... I got the car running about 2 weeks ago, but didn't get to drive it until today and I noticed something extremely off... The last time I made a thread about my car, it had a LIM issue that took me about a year to fix, mostly because I didn't know what to expect. Well now that the car finally stopped surging, cutting off as it warms up, and stays level at around 900 - 1000 rpm when warming up and drops down to 700 when fully warm or when in gear, I'm now having a trans issue.

 

It seems that the transmission is having some sort of problem. What I notice is that going from park to reverse makes the car jump, the same when going from reverse to drive or neutral to drive. The jump is pretty bad. From the outside, the car looks as if it rolls back then goes back forward.

 

That's not the only thing that's wrong though... another thing I'm having as I drive it around is that the car changes gears from 1st to 2nd rather harsh, similar to a stick shift when someone makes a hard shift. It also makes a sound that I can't really describe, but it would be more of a minor bang, once again as if someone is doing a hard shift on a manual car. 2nd to 3rd is fine, but in 3rd gear, mostly around 45mph, the car makes a rather annoying humming sound. My friends and I joke around and call it the plane sound, since it kinda sounds like a plane or something of the sort, but the sound can be loud enough to get really annoying and want to get the car to switch to 4th gear.

 

Anyways, once 4th gear is in place, there's no issues... I used to have an issue where sometimes the car would act as if it was stuck in 3rd when cruising at 70mph but as of now, I can cruise at 60 at 2000 rpm flat.

 

Although the last statement is true, the car does seem to shift hard sometimes, but not sure if that's my alignment or the roads because I don't notice that all the time.

 

Anyways, my question is should I even mess with any sensors to see if it's a sensor issue, or am I royally screwed and have to shop around to get the tranny rebuilt?

 

As always all help is appreciated.

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I've owned the car for a year, never serviced the trans. I did have the passenger trans axle popped off when I had my alternator changed, but that was in June.

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So I would have to change the fluid anyways.

 

Hmm I will ponder that after I check the computer. I got the SES light on, I'm kinda hoping its a sensor to the trans and no the trans itself.

 

Quick question, is the way to fill up the trans through the dipstick, or is there another way to fill it up?

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Make sure all your engine mounts are tight too. If an intake job took you a year to complete it's possible the mounts were forgetten and never tightened up

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Dipstick tube is correct

So I would have to change the fluid anyways.

 

Hmm I will ponder that after I check the computer. I got the SES light on, I'm kinda hoping its a sensor to the trans and no the trans itself.

 

Quick question, is the way to fill up the trans through the dipstick, or is there another way to fill it up?

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Make sure all your engine mounts are tight too. If an intake job took you a year to complete it's possible the mounts were forgetten and never tightened up

 

It only took me a year because I bought the car with bad LIM gaskets, and I didn't know what it was until the car started acting worse. To be honest, the LIM job itself took me 3 days, but that's because my gasket kit didn't come with the o ring for the plenum to block contact. I had to hunt it down.

 

Besides the dogbone, where's the other 2 mounts?

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One on the engine side, one on the trans side, Get it on jack stands, pull front wheels, remove plastic splash shield and you cannot miss them. Block of wood between a jack and oil pan to slowly raise the engine enough to get them out, might have to loosen both but only remove the bolts from one at a time. The manual says to undo the steering shaft pinch bolt IIRC but I did not have to.

 

Would also change trans fluid and see if it helps then go from there. Trans pan drop fluid replacement is 6qt approx. Also make sure you trans filter comes with a small seal for the new filter, one time a kit didn't come with it for me.

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A bad vacuum modulator can make for harsh shifts, since if it's bad, line pressure is at maximum.

 

Might be worth making sure the vacuum hose isn't disconnected to the modulator. Modulators themselves cost less than $20.00. If your local parts guy can't find one for the T460E, one for a turbo-hydramatic 350 will work.

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if the line even looks questionable, replace it.

 

on the 90GP, the line still looked intact and i couldn't find any issues with it other than slight weathering, but i replaced it anyways and it fixed a few issues we were having(super rough and late 3-2 downshift).

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I'll put questioning the transmission on hold for right now. I had a shop check it out and tell me that the humming noise and possibly hard shifting is coming from a bad right front wheel bearing. Now I've never messed with wheel bearings, so is that actually possible that a bearing can cause the hard shifts?

 

A bad vacuum modulator can make for harsh shifts, since if it's bad, line pressure is at maximum.

 

Might be worth making sure the vacuum hose isn't disconnected to the modulator. Modulators themselves cost less than $20.00. If your local parts guy can't find one for the T460E, one for a turbo-hydramatic 350 will work.

 

I'll check this when there's sunlight. Where would I find this vacuum modulator?

 

Trans cooler lines are easy to forget to replace.

 

 

Is this the oil line that has a curvature that runs in front of a splash guard or something of the sort around the subframe? I know I have an oil leak somewhere but Idk what it is. I just know there's a lot of oil stains where a plastic piece that usually sits in front of the subframe is, and it usually looks like motor oil. It doesn't leak very often and it's something I want to address soon and it will get its own thread.

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Vacuum modulator is on the front side of the transmission underneath the airbox, held on by a bolted down tab. IIRC if you pull it and there is oil in it=replace.

 

Oil cooler line is under the engine sort of beneath the crankshaft pulley and it is made of metal and has a few "S" curves in it.

 

Trans cooler line run from the Radiator cap side of the radiator across the front of the engine and underneath to their hook ups, I`d look at the rubber sections that run across the bottom of the radiator.

 

Oil leak could be LIM gasket if it seems to be coming from the LIM valley behind the PS pump.

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Vacuum modulator is on the front side of the transmission underneath the airbox, held on by a bolted down tab. IIRC if you pull it and there is oil in it=replace.

 

Oil cooler line is under the engine sort of beneath the crankshaft pulley and it is made of metal and has a few "S" curves in it.

 

Trans cooler line run from the Radiator cap side of the radiator across the front of the engine and underneath to their hook ups, I`d look at the rubber sections that run across the bottom of the radiator.

 

Oil leak could be LIM gasket if it seems to be coming from the LIM valley behind the PS pump.

 

All right, I will check when I have a chance.

 

I believe that will be the one I'm talking about, but I've seen it before with drops of oil as if it was sweating it out. I know I add oil to this thing monthly and if it sits for a while, it leaks more oil from that location when I first start it.

 

I haven't seen red oil drop from my car, but I will check it regardless, maybe it leaks as well. I know sometimes I have to add more trans oil.

 

I already changed the LIM gasket and the UIM gasket last month. The PS pump itself is dirty and I should probably steam wash this engine or something, but nothing out the ordinary, my oil leak is on the driver's side.

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All right, I found the Vaccum modulator, but it looks dry. Would swapping it for the sake of swapping it be a good idea?

 

Also, my local parts store doesn't seem to carry a specific GM one, but rather a universal one. Would this be a good idea to use or not?

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How is the power output? Mine was terrible but not missing. Determined that one of the Coils was not firing. We found the problem while my friend was holding the #5 spark plug wire while the car was running and didn't feel a thing. Change all 3 coils at about a total of$80. Not easy to do for a 67 yr old . Had to remove the starter. The power problem and the Transmission problems disappeared. The milage improved to 16-17 MPG, In persuit of a solution to the Power problem I also changed the oxygen sensor, the fuel pressure regulator and the vac plastic hose to the fuel pressure regulator. The vac tube was obviously a problem. The oxygen sensor was also bad but I could have skipped the fuel regulator. Oh well parts are cheap. Mine is a 1993 3.4

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I fixed the trans issue, it turned out that somehow the vacuum modulator was disconnected. Anyways, the power is really good now, compared to what it once was, since it would cut off when cold.

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I have to keep replacing my trans modulator line as it doesn't want to stay on the dang thang. The fitting on the modulator needs to be at least an inch long so there is room to put a clamp on it. I replace my modulator with the one from autozone that showed up for the 3100 and 3.4 94 CS, same part number.

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So these things are known to pop off? Because I have never touched anything near the transmission and then all of a sudden, it's disconnected.

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Pretty much...as a general rule, any time I have harsh/weird shift issues with my Cutlass, one of the very first things I look at is the modulator--I've been through 3, including the original that was on the car when I bought it, in 4 years.

So these things are known to pop off? Because I have never touched anything near the transmission and then all of a sudden, it's disconnected.
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