1990 740 transmission problem

I have a problem with my auto gearbox and was wondering if anybody had a
similiar problem and how it was resolved, the gears change ok but seems to
rev high before changing, its as if kickdown is on all the time, when
reversing I have to rev to about 4000rpm and even then it only goes back
slowly, on the open road it accelerates ok but still revs high and is
difficult to keep at a constant speed , thought it might be the clutch but
if I kickdown it accelerates no problem even on a hill..thanks in
advance.....

 

The *best* case scenerio is you are dangerously low on transmission
fluid. Don't drive it until you get it diagnosed.

 

I've checked the fluid level all,ok.......

 

That means that you will probably need to look for a used
transmission, but have it checked first at a shop you trust. You might
get lucky...

 

Given the effort to swap one in, I would be more inclined to rebuild the
original one or have someone rebuild it, or get a used one and rebuild
that. Unless you're doing the work yourself or find a known good low
miles used one, it isn't really cost effective to pay someone to install
an unknown junkyard tranny.

 

This is the AW-31, right? The odds are pretty good with those,
especially if you get one from a wreck with reasonable mileage. It's
always been my understanding that rebuild jobs, unless done by an actual
factory-trained refurb outfit (not a transmission shop), often don't go
well. So I'm going to go with "get a used or certified rebuilt
transmission."

 

AW-71.

They do tend to be fairly dependable, so long as you don't crack the
heat exchanger in the radiator and run water through the tranny.

 

Right, AW-71. I've been away from these cars for a while, now. My
only remaining Volvo is my first car, a '67 122S that sits moldering in
my garage...anyway, a used transmission from a reputable salvage yard
that can tell you it was shifting ok and the radiator wasn't shot, given
a pan drop and clean, filter change and as much new fluid as possible,
is probably a good bet.

 

I had a similar effect in a 244 with AW-70, twice. The cable which
transmits the accelerator signal from throttle to the gearbox was sticky.
Accelerating would pull on that cable just OK but the spring which should
move back to idle position couldn't make it.

Open the bonnet, locate the throttle, note the cable going to your
accelerator pedal and the other going down to the gearbox. Turn the wheel
mounted to the throttle (same as accelerating), let it flip back and watch
the connection to the gearbox: it should follow immediately. If it doesn't
replace that cable (~200 EUR at the shop 10 years ago).

Bye,
Vitus

 

That's the kickdown cable. Unusually you can fix it by squirting some
lubricant down inside the sheath.

 

I'm sure we all thought of the kickdown cable immediately, but most
of us dismissed it as the culprit because of the behavior in reverse.
Did your car do that as well...?

 

Has the oil level been checked properly and is it the right oil?Make sure
the cable on the tranny is loose as can be then tighten to desired effect
..It worked for me .I did the cable by the book and it was a problem ,doing
it slowly up till it was right worked well .I was advised by a Volvo
mechanic to do it this way .

 

I have a '91 740 wagon and had to get my trranny rebuilt for about $ 1000.
I was told that 740s are "known" to have weak trannys although I had not
heard that before or since.

 

The ZF 4HP22 automatic transmission is known to be problematic, the
AW-70/71 is pretty solid. You can tell by looking at the shifter, the ZF
will have PRND321 and the AW will have PRND21 with a button on the side
to lock out the overdrive. All turbo models had the AW.