1999 S70 T5 Auto tranny "engaging/disengaging" on freeway

leonardthefast · Post by **leonardthefast** » 11 Jun 2014, 10:06

Hi folks, Leonard here, new member located in Northern California. Have a 1999 S70 T5 with 147500 miles on the clock; and yesterday on the freeway, the tranny started "cutting out" between 45 - 70 mph. Would downshift when accelerator was fully depressed as usual and not seem to "cut out" until the car returned to a steady cruising speed between 45 - 70 mph. Thank you in advance. Leonard
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Post by **abscate** » 11 Jun 2014, 11:32

By "cut out " do you mean the engine revs like unloaded , while the car feels like it's coasting?

Ugh.

leonardthefast · Post by **leonardthefast** » 11 Jun 2014, 13:30

Nope, actually it's more like the tranny 'disengages/engages' and the tachometer shows neither increase nor decrease in revs.

Post by **j-dawg** » 11 Jun 2014, 13:34

do you feel the car bucking or jerking slightly?

any information on what transmission fluid is in there, when it was last changed, &c?

Post by **Ozark Lee** » 11 Jun 2014, 13:48

One other thing to check is your brake switch. The torque converter lockup will disengage when the brake switch is actuated but that will normally result in a jump of a couple of hundred RPM on the tachometer. It does give a sensation that the transmission is down-shifting though.

If you can get someone to follow you it is easy to tell when the switch is going bad - the brake lights will flicker.

...Lee

leonardthefast · Post by **leonardthefast** » 11 Jun 2014, 14:41

j-dawg wrote:do you feel the car bucking or jerking slightly?

any information on what transmission fluid is in there, when it was last changed, &c?

Yes to the 1st question. I don't know when the oil was changed as I recently bought the car. Within the last 4 weeks.
Leonard

leonardthefast · Post by **leonardthefast** » 11 Jun 2014, 15:10

Ozark Lee wrote:One other thing to check is your brake switch. The torque converter lockup will disengage when the brake switch is actuated but that will normally result in a jump of a couple of hundred RPM on the tachometer. It does give a sensation that the transmission is down-shifting though.

If you can get someone to follow you it is easy to tell when the switch is going bad - the brake lights will flicker.

...Lee

Oh, do you happen to know if there is a a/t fluid filter and is it as hard to change on the FWD mod as the AWD? I'm also going to replace tranny fluid, any suggestions? Thak you.L.

Post by **Ozark Lee** » 11 Jun 2014, 16:06

There is no filter to change. I would avoid having the transmission "Flushed" by machine. It tends to cause leaks. Most of us do a series of drain and fills. Drain out what you can and refill the transmission. After a couple of hundred miles do it again. After three or four iterations the fluid looks new.

Another popular method is the "Modified Flush" which is detailed in the repair database. What you do there is remove the transmission fluid return hose from the radiator, start the car, and then quit after a quart or so has been pumped out and fill the same amount back into the transmission. Continue the process until the fluid looks nice and clean.

Transmission driveshaft bevel gear new modified transmission flush method

...Lee

leonardthefast · Post by **leonardthefast** » 11 Jun 2014, 16:24

Thank you very much.
Leonard