Transmission Surging: 2001 XC70

JohnR · Post by **JohnR** » 15 Aug 2011, 18:55

I recently had the 'auto stop' turned off on my 2001 XC -- has 200,000km. After this program change whenever I ride along under a neutral to light throttle, the car surges up a couple of hundred rpm, then back again. It does this in both gear 4 and 5 -- I check by taking it out of drive and into manual mode. When in manual mode the surging does not take place.
This surging feels like the transmission is coming out of lock-up, and then back into it again.
Other than the transmission slamming from 2nd to 1st when it is hot from stop-go city traffic, the transmission appears to be just fine.
Any suggestions about what might be going on after this 'fix?'
Many thanks!

Post by **JRL** » 15 Aug 2011, 20:19

It's not fine if it's slamming into 1st
It's on the way out....sorry

Post by **jimmy57** » 15 Aug 2011, 22:35

Those are symptoms of valve body and linear solenoid problems. It is a gamble to put a valve body in but if the symptoms are new a valve body stands a pretty good chance of fixing it.
There are a lot of AW 55-50's in use, more in non-volvo applications. The auto trans repair industry has got a pretty good grip on these. There are a lot of them fixed with valve bodies. Valve body and solenoid issues will kill the gearbox due to low apply pressure on clutches.
I put a valve body in an S60 last week that I really figured was in vain. The slow shuddering engagement in D I was pretty sure was a clutch failure or at the least a leaking piston seal and a weakened clutch lining set. I replaced the valve body and it took care of all the ills of that transmission.

Post by **JRL** » 16 Aug 2011, 05:18

jimmy57 wrote:Those are symptoms of valve body and linear solenoid problems. It is a gamble to put a valve body in but if the symptoms are new a valve body stands a pretty good chance of fixing it.
There are a lot of AW 55-50's in use, more in non-volvo applications. The auto trans repair industry has got a pretty good grip on these. There are a lot of them fixed with valve bodies. Valve body and solenoid issues will kill the gearbox due to low apply pressure on clutches.
I put a valve body in an S60 last week that I really figured was in vain. The slow shuddering engagement in D I was pretty sure was a clutch failure or at the least a leaking piston seal and a weakened clutch lining set. I replaced the valve body and it took care of all the ills of that transmission.

With 140000 miles???

dbeckwith · Post by **dbeckwith** » 16 Aug 2011, 06:28

Jimmy57, were you able to change valve body without removing transmission? Would the process be similar with an 850? I would really like to see an illustrative tutorial on this

Post by **jimmy57** » 16 Aug 2011, 08:00

The 4 speed in the 850 is completely different gearbox and doesn't have the pressure regulator solenoids controlling the shifts.
The 4 speed doesn't have the same issues.

Post by **jimmy57** » 16 Aug 2011, 08:35

JRL wrote:
jimmy57 wrote:Those are symptoms of valve body and linear solenoid problems. It is a gamble to put a valve body in but if the symptoms are new a valve body stands a pretty good chance of fixing it.
There are a lot of AW 55-50's in use, more in non-volvo applications. The auto trans repair industry has got a pretty good grip on these. There are a lot of them fixed with valve bodies. Valve body and solenoid issues will kill the gearbox due to low apply pressure on clutches.
I put a valve body in an S60 last week that I really figured was in vain. The slow shuddering engagement in D I was pretty sure was a clutch failure or at the least a leaking piston seal and a weakened clutch lining set. I replaced the valve body and it took care of all the ills of that transmission.
With 140000 miles???

The S60 had just a little below that milage. It was getting a valve body with a gearbox overhaul or a valve body. I air tested all the brakes and clutches and all were sealed. If I had found leaks in clutches and brakes from air tests then I would pulled the transmission and gone on with a teardown. The pressure tests I did first looked like bad seals due to very slow pressure build on the forward clutch. The 5 speed doesn't turn on a valve to apply oil pressure for that clutch, it changes pulse width on a linear solenoid and the pressure goes up so bad bore in the linear solenoid builds pressure slowly and can look like internal trans leakage. There are a couple of spool valve bores in the valve body that tend to wear and those binding can cause 3-2 and 2-1 harsh downshift.

Post by **JRL** » 16 Aug 2011, 10:20

Ok
But he said he JUST removed the stop neutral
To me that's about 130,000 miles of the tranny being pounded to death, clunk in, clunk out, etc
It's amazing it's still in one piece.

I think you were lucky
When my daughter's 2002 C70 tranny (5 speed) started to slip and I went to have it rebuilt, they said they couldn't, the case was too worn out!
And this was at only 80K miles

JohnR · Post by **JohnR** » 20 Aug 2011, 19:12

Thanks for the dialogue. I think the 'red herring' was the last comment about the transmission slamming from 2nd to 1st only when the transmission is really hot, and there has been a lot of stop and go in the city. But the 'real' problem for me is the surging of the car after the transmission module has been re-programmed to eliminate the auto stop. Is it the valve assembly which creates this surging, or is it the electonics -- one of the many modules?
Thanks!