960 Mk2 Yucky transmission fluid

[taiwan740]

Every six months or so since owning this car I've been replacing the ATF with fresh red Dexron 2 (Gulf) - I do this just by replacing what is in the sump and refilling it as opposed to anything more harsh because reasons, mostly due to being lazy and lack of suitable tools other than a 14mm socket.

What normally prompts me to replace the fluid is a very slight wobble feeling when changing up into second gear (no slippage once its engaged). Every time I replace the fluid, the stuff that comes out has no hint of red whatsoever and is black, perhaps you could describe it as yellow in a very small sample. Never red.

I imagine one of the clutch packs is worn out or possibly overheating burning the fluid and I'm due a replacement gearbox or a rebuild - am I right?

Of course I'm going to do nothing until it is stuck in 4th gear permanently, as there's no failure like catastrophic failure

Mileage is 205k, previous owner used it for towing horses but not that often, and its a AW transmission, the one with the lockout on 3rd and 4th I think. Gonna say its a AW70 because Cunningham's Law.

[Shroudedknight]

Originally Posted by taiwan740

Gonna say its a AW70 because Cunningham's Law.

It should be an AW 30/42 (or possibly an AW 30/40) rather than an AW 70

[Laird Scooby]

Try a slightly different method and definitely a different fluid!

https://www.ebay.co.uk/itm/Electric-...K/174146415941

Get yourself one of those, reverse the car onto some ramps (so the back is higher than the front) and switch off - make sure you take it for a run of about 5-6 miles first to get the ATF hot.

Remove the transmission dipstick, feed the suction tube from the pump down the dipstick tube as far as it will go, arrange the discharge tube into an empty 5L container (preferably clear, there's a reason for it being clear), connect the clips to the battery, switch on and once it starts pulling fluid through, go and have a coffee or whatever for 20 minutes or so.

Come back and if the pump is still pumping, let it finish. When it's finished, switch off, put the lid on the clear 5L container and estimate how much fluid came out. Then put it somewhere it can sit overnight to settle.

Refill the box through the dipstick tube in the normal way with about 0.5L less than your estimate with fresh :

https://www.ebay.co.uk/itm/Carlube-A...L/233257297843

Get the car back on the level, check the fluid level and top up to the COLD mark. Take it for a run and then recheck the level, topping up to the HOT mark.

Repeat every 3-4 weeks 3 or 4 times until the fluid remains clean then repeat at 6-12 month periods to ensure it stays clean.

What you've been doing is only changing enough of the fluid every 6 months to keep it dirty - the old fluid contaminates the new fluid so it overheats. Also the later AW30/40 boxes tend to be a bit more picky on fluid and Volvo (not to mention Aisin-Warner who make the boxes!) recommend a different fluid to Dexron II which is JWS3309 and Carlube ATF-U meets that spec. You can also use ATF-U as PAS fluid and hydraulic jack fluid too or mix it 50/50 with acetone (nail varnish remover), shake it up and use it as a penetrating fluid to beat all other penetrating fluids.

Also as it's a 960, replace 0.5L of your normal engine oil with ATF-U to cure ticky tappets, improve compression, reduce oil leaks and generally clean the engine internally. You can do this on other engines that don't have hydraulic tappets of course but obviously it won't make much difference to ticky tappets on them!

Nearly forgot - check the old fluid after it's settled overnight to ensure there's no coolant in it (it will be at the bottom if so) and see how much filth is in there.

[Volvoluke]

I have just used the method suggested above and it worked very well. I simply parked my car facing down a hill and siphoned it out

[taiwan740]

Thanks, I'll give that a go.

At the moment I'm changing the power steering fluid as well, and also adding ATF into the oil to stop hydraulic lifter noise, and ATF in the fuel to prevent the fuel pump from whining, as recommended by you guys.

Laird Scooby - do you own an ATF factory by chance?

[Laird Scooby]

Originally Posted by taiwan740

Thanks, I'll give that a go.

At the moment I'm changing the power steering fluid as well, and also adding ATF into the oil to stop hydraulic lifter noise, and ATF in the fuel to prevent the fuel pump from whining, as recommended by you guys.

Laird Scooby - do you own an ATF factory by chance?

I wish!

Just passing on things i've tried, tested and learned over the years.

[taiwan740]

Originally Posted by Laird Scooby

Get the car back on the level, check the fluid level and top up to the COLD mark.

I gather the fluid level should be checked with the engine running after running through the shifter? ( P -> R -> N -> D etc.)

[Laird Scooby]

Originally Posted by taiwan740

I gather the fluid level should be checked with the engine running after running through the shifter? ( P -> R -> N -> D etc.)

Pretty much, what i usually do is P>R>N>D>N>2>N>1>N>2>N>D>N>R>P, waiting a second or two to let the box change each time.