AW 55-51SN XC70 D5 transmission slip

jimka · Post by **jimka** » 14 Apr 2022, 08:07

Hi all -

My 2003 XC70 D5 AWD euro3 with 340K KM has suffered with a really annoying transmission issue for 3years. It could be that's its just ready to die!

I just don't know when.....

Gear changes are perfect and smooth, no flaring, selection is fine including reverse and switching between P,R,N,D. Oil has been flushed (sensibly over the last 2 years and is a good colour - Volvo genuine) level checked whilst hot and is within the levels on stick.

The car will slip each gear (the rev's will stay at ~3000rpm until the speed catches up for the next gear change) all the way until ~55mph when the torque convertor finally locks. I can travel for endless miles (across Spain recently) with no issues if the speed stays up above 55mph with no slipping.

VIDA is giving no fault codes related to transmission.

Anything I can investigate without removing box? It could just be the clutch packs are worn but wondering if I'm overlooking something obvious?

Thanks

Jim

Post by **vtl** » 14 Apr 2022, 10:10

What do you mean exactly when saying "gear changes are perfect" and "slip each gear"? Since you mention ATF's good colo(u)r, it probably does not slip, as the slipping friction clutches make ATF very black in no matter of time.

jimka · Post by **jimka** » 14 Apr 2022, 11:16

as in, no knocks/jolts between gear changes, very smooth between gears - no flaring.

When you pull off for example the rev's will shoot up to 3,000rpm and sit there until the speedo catches up, it repeats all the way until the torque convertor locks up.

If you climb a mountain road it will be high revving but maintain the speed - obviously this is similar to a manual car with the clutch being ridden.

Post by **vtl** » 14 Apr 2022, 12:11

How the car accelerates? Sluggish or fine?

TC locks up starting in third gear.

Post by **vtl** » 14 Apr 2022, 12:16

Let me ask this question: is it your first car with automatic gearbox? =) Unlocked torque converter transfers only around 2/3 of torque available on crankshaft, since torque transfer media is fluid. This is normal. Until TC locks, engine speed has little relation to wheel speed, it is definitely not as linear as in cars equipped with manual transmission.

jimka · Post by **jimka** » 14 Apr 2022, 13:11

No, it's clearly not my first auto. This isn't just a sluggish box, if you floor it in 2nd it will go straight around to the red line and the speedometer will catch up some 10 seconds later - the RPM needle will basically be near the red-line.

I've been in other XC70's that don't do this. The rev's may be slightly higher to help create a smoother journey but not to this extreme.

The car will hold 3rd from 20mph to 60mph near the red line until it catches up for example. Once @55mph you physically feel the torque convertor lock in and it drives like a normal auto.

Aux are fine. DPF has been deleted and I've mapped it using V-DASH. It was doing this beforehand though.

Post by **vtl** » 14 Apr 2022, 13:16

So, unless you have transmission sump full of black soot (the frictions remnants) TC turbine wheel is bad?

Post by **firstv70volvo** » 14 Apr 2022, 14:17

vtl wrote: ↑14 Apr 2022, 13:16 So, unless you have transmission sump full of black soot (the frictions remnants) TC turbine wheel is bad?

This does sound like a torque converter problem, might be the stator one way clutch is bad. Wonder if a stall test could confirm this?

Like you said Vtl, if one or more of the clutches were slipping the fluid would be black and I would expect you'd see error codes and limp mode too. I'm surprised there's not a code for a big difference between the engine RPM (crank sensor) to transmission input shaft speed senor feedback. Maybe this difference is only checked when the torque converter is locked up. No way this transmission could last long if a clutch was slipping this badly.