L322 3.0 td6 gearbox problems

Hello all. I am new to the forum and looking for a bit of advice regarding the transmission in my newly acquired RR L322 3.0 TD6.

So the issue is if I pull away from a start using a fair bit of throttle and accelerate swiftly it pulls normally and changes up through the gears as it should. But if I pull off and drive normally the transmission seems to be slipping, the revs rise and stay up and the speed increase slowly abit like a cvt transmission.

I can hear it change gears but revs only drop a little. If you let off the throttle the revs drop to normal then Increase again as soon as you touch the throttle.

But once up to main road speeds about 50+ mph and I guess it's in top gear it drives fine and you can accelerate without any abnormal increase in revs.

I will add at this point that there is a receipt from 2k mile ago stating it's had a remanufactured torque converter and new frictions and seals. But there is no mention of any valve body work.

Could this just be down to a worn valve body?

Thanks in advance for any advice that is offered.

First step might be to check there is the correct amount of ATF in there. You have to follow the correct procedure to do this.

Thank you for taking the time to read and reply. I probably should of mentioned that I have already checked the transmission fluid. Had car up in air with transmission warmed. Fluid was 48c when I check. Engine running cycle from park to drive pausing in each for a few seconds. No fluid came out initially but when I tried to top it up it only a tiny bit before it ran out so I guess it was near enough.

MrMatt83 said:

Thank you for taking the time to read and reply. I probably should of mentioned that I have already checked the transmission fluid. Had car up in air with transmission warmed. Fluid was 48c when I check. Engine running cycle from park to drive pausing in each for a few seconds. No fluid came out initially but when I tried to top it up it only a tiny bit before it ran out so I guess it was near enough.

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OK, what mileage has the car done? The GM box rarely lasts much longer than 80/100K miles. I'm not an expert on that box but it sounds like the torque converter lock up clutch to me. The valve blocks are made of cheese. @Bemble is the man who would know.

It's now done 164.5k miles. According to the receipt the gearbox had new seals and friction plates and a remanufactured torque converter was fitted 2k mile ago. No mention on receipt of any valve body work being done.

I find it strange It's perfect when giving it large but not under normal pottering around conditions.

The torque converter utilises variable lock up which may account for it but I'm only guessing

Oh right ok thanks. Maybe the torque converter isn't much cop then. Thank you for your input it's much appreciated.

MrMatt83 said:

Oh right ok thanks. Maybe the torque converter isn't much cop then. Thank you for your input it's much appreciated.

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I did say I'm only guessing. Diagnostics might show something. Overhauling the box without fitting a Sonnax valve block is IMO a waste of time.

changing the torque converter without rebuilding the box and fitting new cooler lines and radiator is also a waste of time

Yes I agree it does seem a waste of time not to change oil cooler and check the valve body. The box seems to have had a partial rebuild as it's allegedly had new clutch friction plates and new seals as well as a remanufactured torque converter. But no mention of oil cooler or valve body on the receipt.

I guess I'm just trying to work out if I would get away with having the valve body tested and rebuilt and fitting a new oil cooler and filter.

if the cooler was full of bits of the gearbox before it was rebuilt those bits are probably now in the rebuilt box

So I'm guessing it could be screwed again already then. Might have to drop the sump and see how it looks. Check for dreaded metallic sludge.

Not sure what metals are in there, but next time you drain it, dip a magnet in the oil & see what sticks to it ?