Transmission Acts Up When Warm

[wheelsup]

144k, 1995 850 GLT (N/A) Auto

Been having transmission issues over the past couple years. Started a few years ago or so and has progressively gotten worse.

At 140,000 or so I added Lucas Transmission Stop Slip, that made the transmission buttery smooth and seemed to fix the issues. But they are now back, and worse.

I notice it now on extremely hot days (NC) and/or driving for 20-30 minutes. After driving at around 50mph and above, then coming to a stop, the car makes a hard downshift what seems to be 2nd to neutral. I hit the gas and it revs (slips) a bit, then catches.

Shifting up thru the gears is great, maybe a bit harder than in the past but still really nice for a car with 144k miles on it.

At 143,700 miles or so (few weeks ago) I did my first drain and fill using generic Dex III ATF. This seemed to reduce the dropping into neutral bit, or it could've just been cooler out.

About a week later, did another drain and fill.

Now it almost seems like it's dropping from 3rd to neutral, or maybe just happening at a higher speed in 2nd.

Taking it out to get some new tires today, the drive down went well. It was cooler today, transmission did well. No hard downshifts, no dropping into neutral or slippage.

Coming back about an hour later, after the car had been warmed up, it did it at every stop after accelerating above 50 mph or so.

I've tried popping it into neutral when decelerating, then park when stopped, then manually putting it into drive or even "L" (1st gear), but it still seems to slip when accelerating until it catches.

I'm thinking there are several contributing causes:

- A warm car, and/or hot weather (seems to do it more in hot weather)

- Shifting up into 4th or 5th gear, then back down thru it

I'm thinking hot transmission fluid is hurting the transmission. It seems to do well when cool, so I'm hoping it's still OK as far as continued life. But I'm thinking about adding an additional oil cooler for the transmission fluid. Any thoughts on this? Anyone done it? Think it will save it or should I just drive it till it dies? (might be soon, seems to be happening more often ).

-matt

[wheelsup]

Forgot to add, I get a lot of slamming when the car is warmed up when going from "D" to "R" or vice versa. When cold, it doesn't do it.

[Mete Goktepe]

Hello,

I want you to know that I have been going the same issues with my 95' 850 GLT (auto trans) which has 180,000 miles.I have been draining and refilling the fluid a several times. first you must know that the only proper fluid to use with these gearboxes are Dexron IIE other fluids will not fulfill the requirements of the gearbox and malfunctions will occur sooner or later. there are 3 different possibilities causing your problem. first one is the control unit located infront of the gearbox has one or more than one solenoids failing. these solenoids are responsible of shifting, and one is responsible of adjusting the system pressure. 3 solenoids are replaceable but the fourth one is not if the fourth one fails the control unit needs to replaced as an assembly. the second possibility is that transmission system pressure might be low in this case a remanufactured gearbox or a replacement (used or new) is the best choice 3rd possibility is that your gear position sensor is bad. in order to find out if the system pressure is low or not when the engine and transmission are in operating temperature control the lag when shifting between all the positions. from P to L and then back to L to P between any of these there should be a delay of max 1.1 seconds. if the delay is bigger it means that system has low pressure. also be sure that the fluid level is near or at the maximum level low fluid will cause lack of power or slipping. if you have more questions you can Pm me too.

I forgot to tell you that my transmission was finally replaced by a new one.