Transmission Slip

I own a 1998 Oldsmobile Intrigue, also known as a P.O.S. I have owned the car since May and ever since I owned the vehicle after about 25 minutes of driving, the car develops a much harder shift when shifting into any gear. I took the car to both my general repair mechanic and a transmission specialty shop and both said that the car is fine and to ignore the hard shift. When I bought the car in May, it came with a re-built transmission. The hard shift has gone away, however, a much more concerning problem has arisen this past month. I did all of the obvious things, I checked the fluid, it’s fine, full and not discolored. Now, at highway speeds(55mph and over) when climbing a slight hill, the car feels like it comes out of gear (at the point when I fell it should be shifting into overdrive) and tries to shift (I assume it’s trying to downshift for more power going up a hill) but then slams back into gear. This whole sequence of events occurs in about a second. I feel a jarring feeling in the driver’s seat. It feels like the transmission wants to shift, but can’t, or that it’s slipping. The car shifts perfectly at low speeds, but any highway speed going up any sort of hill and I get the problem. I again took it to a transmission shop and they scanned it and said it was the valve body. I don’t know what this means. I added a half bottle of Trans-Tune by SeaFoam to the transmission and the problem went away for 2 weeks. What is causing this???How much will it cost to fix? Is the car reliable even though this problem exists? Will the transmission fail on me while I’m on the highway. I’ve done some research and some possibilities for this car seem to be the Pressure Control Solenoid or the torque convertor, although I was told the TC was replaced when the tranny was re-built. Why did the problem go away for 2 weeks after I added the trans-tune? I can’t afford another car, I am a poor college student. Any help/suggestions would be greatly appreciated. The car still shifts fine, at highway speeds I get that 'slip" though. Thanks!!!


Pouring additives into a transmission to try to resolve a problem is not usually a good idea. The only one I have seen endorsed by anyone on this site is Berryman’s, but I will not recommend anything like that right off the bat. There are others on this site more knowledgeable than I, including a transmission expert, so hopefully one of them will come along and weigh in on this subject.

Well, Mike. What you have there is what seems to be a Jekyll and Hyde transmission. Some of them seem to have long term reliability. Others have all sorts of problems and when they do, no on seems to know what to do about it - including GM. That’s not an expert assessment - I just have a vehicle with the same transmission in it and probably the same problems you have had.

First thing’s first. When you took it to your mechanic and to the transmission shop (both times) the car was probably scanned for error codes. Find out exactly what the error codes were and post them here in their exact format. They look like “P1234”

What do you know about the rebuild? Was it rebuilt at a local shop and is that the same one you have take the car to?

When it was doing the hard shifting was it the kind if thing where if you shut the car off - even briefly - and started it back up it might be normal again for a while? And did you ever notice a whining sound when you were getting started, like down in first and second gear?

When it is jerking on hills is the tachometer (if you have one) sort of shooting up and down about 3-400 RPMs? For the time being, when you hit a hill of any decent length and size either stomp the gas to get it to fully downshift or just move the shifter to the 3 position instead of leaving it in D. The problem is probably not that its trying to downshift or something, but probably that its bouncing in and out of torque converter lock up. Downshifting won’t completely avoid the problem, but it will help avoid it.

The above is a guess, so get the codes and post them.

Has anyone (like your own mechanic) checked out basic things like your fuel pressure, spark plugs & wires etc? You do have to rule out the possibility that this is an engine problem (such as a misfire). Report whatever you know about the car’s maintenance history and condition. Once again, having the codes will help.

Thanks for your input guys! I don’t have the answers as far as the specific codes go…but I’m sure I could get them for you. Maybe I could provide a little bit more detailed description of the problem…Again, it only occurs at speeds above 50mph, and the problem is most pervasive went going up any sort of incline at highway speeds. As I go up a hill, I can sense the engine begin to labor, the RPM’s drop down to about 1400, my speed begins to decrease (obviously)…if I keep my foot steady on the pedal or try to accelerate even just a little, it feels like the transmission comes out of gear momentarily…likes it’s trying to shift into OD but then rapidly and kind of violently goes back into gear. One one occasion I had this problem occur while I was going down a steep hill on the interstate with my completely off the accelerator…the whole car jerked for a few seconds…like it was going in and out of gear…the RPM’s flucuated rapidly between 1300-1800 RPM, but that was the only time it has happened going down a hill…any incline seems to trigger the problem.
I bought the car from my mechanic…which may have been a mistake. It came with lots of goodies…new pads and rotors, barely used tires, new power steering pump, new water pump, replaced the rear main seals on the engine, and…a re-built tranny. The transmission work was outsourced to a friend of my mechanic who specializes in doing transmission work. I called him (the tranny guy) when I started getting the slip and he insisted that it could not have been anything he had worked…and of course…the six month warranty on the work was up. he said that he just fixed what was wrong with the transmission and then sent the transmission to my mechanic to have it installed on my car. He said he doesn’t remember what he fixed on it. He wished me the best…but that was about it. He mentioned it could be that I need a new shift kit and that it “sounds like a locking type problem…not the transmission per say”.
I will admit that I have never even considered this could be an engine problem…in my gut I truly believe that it is transmission related…I can’t convince myself that an engine problem could jerk the car that much.
The car has never failed to get me anywhere…it’s just incredibly nerve-wracking to drive…when it slips it feels awful…and the feeling going up a big hill is terrible…knowing that it’s gonna slip at any moment.
Thanks again for all your help…maybe with your help I can go to my transmission shop with some ideas about what the problem could be. I’ve gone there and had both the owner and technician sit in the passenger seat while I drove around for a half hour and tried like hell to replicate the problem…and of course…she drove beautifully!!!
They tell me that they really can’t diagnose it until I can replicate the problem.

On a final note, someone mentioned a torque converter clutch that could be causing my symptoms…is there such a thing? Could it be causing my problem? How likely is it that this could be the culprit even though the TC was replaced during the re-build?

Oh, and about the whining…I do hear a very faint sound that the car always makes when accelerating…but I’m not sure I would classify it as a whine…it’s very faint…and in my humble opinion, it sounds more like an engine noise. Yes, you are exactly correct as far as stomping on the gas is concerned! As soon as I feel it slip, I take my foot off the gas and allow the car to downshift and then floor it to kick the RPM’s back up to about 2500-3000. That seems to alleviate the problem. I will give the 3rd gear option a try tonight on my way home from school, that sounds promising. When I experience the problem and glance down at the tach, it usually registers about 3000 RPM, like the car may be trying to downshift, but can’t. That’s all for now, I think I may have posted this reply out of order. I hope you guys can sort it out. Thanks again for all of your help!


1998 Oldsmobile…Any serious transmission repair will cost more than the car is worth…As long as it will drive, just drive it…Try locking out the overdrive and see if that doesn’t cure the funny shifting at 55…

Caddyman, how do I lock out the overdrive?


You can’t. This transmission is idiotic in its design in that respect. Actually the whole meaning of this is ambiguous in this case. Overdrive is just 4th gear. A lot of cars will have a way to turn off “overdrive” which will normally cut out the highest gear and turn off the torque converter clutch (TCC).

So yes, you have a TCC. All automatics do these days. When you’re at a cruising speed and don’t need any extra torque (power) this locks the engine & transmission together so that they are both spinning at the same speed. It saves gas.

This transmission, however, has no way to disable the TCC (stupid, stupid, stupid). It will lock up anywhere between 2nd and 4th gear. This is why downshifting on hills will help - you’re less likely to hit the “cruising” conditions that will have the TCC locking up. But it can still lock.

I do think that you are having a TCC lockup problem. (The codes might help when you get them). I say this because I live with one in an Olds with essentially the same drive train and your description sounds just like it. But you have to keep in mind that I can only guess about this.

I have a bad feeling about “tranny guy.” If tranny guy just rebuilt this thing then he should be taking your concern seriously and if he was a stand up sort of person would be taking care of it - its called standing by your work. If he’s at all a serious tranny guy then he has the right scanning equipment that he can hook up to your car, drive it around and actually do diagnosis. It sounds like both of these guys want to brush you off long enough for you to go away.

Anyway, still put a priority in asking about the error codes. But you can also ask your mechanic to do a few simple things (if he’s at all competent). One is to put the car on a scan tool and check out the operation of the throttle position sensor (TPS), the mass airflow sensor (MAF), and the MAP sensor. Even if he doesn’t see anything funny about the MAF behavior ask him to clean it. Also ask him to take a close look at the car’s main wiring harnesses, especially in the area around the accumulator for the A/C system.

I’m almost certain that this transmission is the 4T65E. There is some chance that it is a 4T60E but I’m pretty sure most of these were 65’s as of 1998. However, if it is a 4T60E, that transmission has a vacuum modulator that is a fairly common problem and is not expensive or difficult to replace. So ask your guy (or tranny guy) if its a 4T65 or 4T60. If its a 4T60 ask them to check the vacuum modulator.

So what happened when the transmission shop said the problem was the valve body?? Did they fix or replace the valve body?? It sounds like to me that the converter clutch is falling in and out of lockup. It most likely is in the valve body. A worn regulator valve causing low pressure in the converter clutch hydraulic circuit. You asked about locking out O/D, thats simple, just move your gear selector down to “D” position. It could also be labeled as “3”. If your gear selector is in overdrive position (The letter “D” with a circle around it) then the transmission will shift into overdrive. DO NOT attempt to disable the converter clutch. Doing this will overheat the transmission and damage it. Remember now, this transmission is NOT a rebuilt transmission. You said the tranny guy your mechanic friend used told you that he just fixed what was wrong with it, which is a waste. A transmission that old should have been rebuilt, not just repaired. You are probably looking at going back into this one. Dont take it back to your mechanic’s tranny guy friend. No telling what he will (Or wont) do this time.


Thanks guys, I am taking the car to a transmission specialty shop tomorrow (with an excellent reputation)and I will get back to you. I spoke with the shop today and they said that they do not believe (but aren’t 100% sure) that my transmission has a vacuum modulator, but they did say that the TCC could be the culprit. Also, they did NOT replace the valve body, which is an expensive fix, they simply scanned it and it kicked a code that indicated the valve body. One final question,

Will shifting from Drive to “3” at highway speeds do any damage to the transmission? Is it okay to shift into 3rd even if I am climbing a hill? Should I shift back into D after I get to the top of the hill? What’s to say that the transmission won’t slip in #rd the way it does in drive?


It wont damage the transmission.


Note that there isn’t a code that can tell you squat about the valve body. There may be a code that indicates a problem and the cause of that problem might ultimately be a valve body problem. As transman noted valve body wear in the bore for the solenoid that controls the TCC is a common problem on these transmissions, and that problem will set codes.

If you get the word that you need a new valve body, there is no point in doing this without a full rebuild. You might also ask them whether they are familiar with repair kits that are meant to address this problem - a company called Sonnax makes one. This might not be a smart thing to do, but I always like to know what all of my options are.

It is also the case that these transmissions (as you heard) have had chronic problems with the pressure control solenoid. That can contribute to TCC lockup problems. If any work gets done to the transmission make sure that you end up with a new and upgraded PCS. The part cost in negligible in comparison to the labor.