98 240SX transmission Problem

[Cassie]

I have a 98 240sx with an automatic transmission. I have had my car 10 years and it has 135k miles on it. A few months ago I began noticing an issue with my overdrive. When I am driving on the highway at about 75 mph, sometimes it feels like the transmission slips out of overdrive or becomes disengaged. The RPM's will go to about 4000 - 5000. It will slip out of overdrive for about 30 seconds and then go back in to overdrive. It only does this sometimes. Sometimes it may go a week before it does this - other times it might do it 2 days in a row. Of course, when I take it to the shop, they can not get the same response that I do and there are no transmission codes. Can anyone help with this???Thanks!!

[Goldeneagle]

Overdrive (4th gear), for the automatic transmission, usually will kick in around 80 mph or so. As long as the transmission shifts between the first three gears, do not worry about it.

While I still had an automatic transmission, I rarely felt the fourth gear kick in until I got up above 75 mph close to 80 mph

[fczero240]

^^^ not true, overdrive will kick in at any speed above 55 mph. if yours was only engaging at 75+ something was wrong with your transmission(you may be thinking of a torque converter clutch solenoid which can feel like another shift), as for OP chances are your shift solenoid for OD is going out, its not an expensive repair. if your mechanically inclined you can do it yourself for parts cost of around 50-75 dollars or a reputable transmission shop can do it for around 150-200

[cosmos2supra]

I have a problem with my 95 automatic, it started to grind all of the sudden. But it shifts though all the gears. Does urs have this problem.So what does happen is some solinoid goes bad, Does it grind like mine.