AW71 strange stuff

[HenrikGM]

I will explain this in english, but feel free to answer in swedish

I have recently installed a AW71 from a B230FT into my wifes 97 945, swapping out the M90.

Took some time to get everything in place , but it finally worked.

The gearbox is only 6000km old, comes from a old totalled car that got a new transmission 6000km before the accident.
When installing it i gave it new Castrol transmax dexronIII. inside the oil pan everything was like new, despite being sitting for 7-8 years.

Cars has been running fine for some 200km, nice firm shifts, everything feels ok. Oil was topped up to exactly between min and max level. It took approx 5,75liters. Converter was never off the gearbox.

Today my wife calls me explaining the car is nolonger moving. One a piece of straight road, the engine lost connection to the gearbox in a few seconds. No reactions in any gear.
We then towed it back some 10km(with the engine running).
Checked the oil, which now is very high level, 15mm above max hot level.
Leaving the car stopped for 5minutes restores the gear so i can drive it in any gear for approx 30seconds, then drive disapperars in a few seconds(not even pulling slightly)
This can be repeated many times.
If the car is started and left idling for 60seconds before engaging a gear, then there is no reaction at all in any gear.

Could it be so, that there is an issue with the converter so it empies itself without being refilled ? Thinking this half full converter could then explain why the oil level is high now?

Oil has been checked for water, no signs of it at all.

Any good ideas from the audience in the forum?

[mauser240]

First of all, the radiators do fail, and that will kill the box in minutes...

I assume you know how to check the oil but anyway, the box should be hot, the gearbox newly driven in all gears (including reverse) and all gear-selector modes. Then you check the oil while engine running and lever in "P-mode". Any other way to check the oil can only be considered a guideline.

To much oil will cause the oil to foam and the converter / box to slip.

[HenrikGM]

Car is not loosing any water, and taking an oil sample and heating it reveals no significant water content in the oil.

Foaming maybe.... Have drained off oil to be on the max when cold. No change.

Starting the car and engaging drive or reverse right after startup makes the car roll instantly. Giving it some throttle almost makes it spin the tires, but then after some 30 seconds all pull goes away in some 3-4 seconds. Like if the converter runs empty or something inside is slipping completely, like in letting go. Im sure its not even able to overcome turning the rear axle off the ground when this occurs.

If i give it 2minutes, i can repeat it again, but not immediately.

If the oil is foaming, then it is something that happends really fast. Is it the wrong oil?? Castrol Transmax DEXIII multivehicle.

There is no abnormal noises to notice anywere.

Should i start to check the different pressures? Or take a shot if something is blocking the oil strainer?

[mauser240]

If the converter runs empty, it will not fill itself back up by letting the car rest. Any DexronII or higher should do the work but I've heard many people recommending the Mobil ATF320 for the AW.

What does the hot oil check that I just described tell you? When the power is gone, is there ANY hearable "banging" selecting between R - N - D?

It probably won't hurt to remove the pan to see what it has eaten but this really sounds like an oil-related problem. Although I can not understand how the amount of oil could grow by itself (more than it does from heat). That would mean you have somthing else in pan that should not be there.

[HenrikGM]

Hi Martin.

Thanks for the support.

R-N-D shifting back and forth when the power is gone makes no noises at all. Not when the power is there, nor when it disappers.

Letting it idle in D for a few minutes and taking several dipstik checks reveals the volume is allover the place, from full to low. There is a variation of approx 4cm. I do know this sounds like i cant read a dipstick properly, but thats not the issue.

Secondly, if i start it after rest it has power if R/D/2/1 is selected right away. Power will then disapper rather abrubtly.
If i then start after rest, and let it idle for same period, power is not there when RD21 is selected.

It will in other words consistently disapper by idling for some 25-45 seconds regardless of gear, rpm, and seemingly also oil level.

I may be getting really noise sensitive as sideeffect of not understanding the issue, but maybe there is a slight whining when the power is gone. I cant tell if its just the cambelt i can hear or not(im starting to hear things!!)

Over many years i have learned to trust my gut feeling, and right now its telling me that somehow im loosing oil pressure in the gearbox. Still missing too many pieces to get the picture though...

[HenrikGM]

The AW71 oil level is supposed to be checked in idle. Now, if i do have a foaming problem(which i cant detect) causing me to be tricked with higher level than anticipated, then the issue may be the oil level is in reality too low, but masked by foaming....

Then it would be really usefull to know that oil level a std 945 with aw71 would read on level ground, just to get a ballpark figure to aim for cold. Anyone has this?

[jonas landin]

Maybe the filter has come loose??

[mauser240]

Hello

Add the amount of oil that you let out + half a litre or so, and try again. The box won't blow up instantly. It really sounds like you don't have enough oil.

When engine has been shut for some time and oil is cold, I would add oil up to 3 cm over the black plastic part and try to work it out from there.

I could have a look at my own but that's a lock-up and I'm not sure they have the same stick.

[mauser240]

So I checked my own and there's oil up to about 1 cm over the plastic part. -7 degrees.

As you understand, that can't be used as a reference if there is air in the system.

What is your stick reading, oil cold, engine shut?

EDIT: Is it possible that your AW71 is actually a AW71L and that the problem occured the first time it locked up?

[HenrikGM]

Thanks for the reading.

I have a stick reading approx 20mm down on the plastic part. engine not operating for 1,5hours, room temp 18degrees.

So thats a fair bit lower.

It was driving steady speed 90km/h at constant throttle for 2-3km when it occurred. I actually dont know if its a lockup transmission or not. How do i tell?

Edit; The Donor car had VIN 944816S, so according to the vin decoder it was a lockup converter. However, the transmission was replaced with a new item, but unfortunately the nameplate is useless.

[mauser240]

I don't remember how to identify the lock-up box but google will help, that I know. I someone spent the money on a new box, he / she probably woudnt leave out the lock-up.

Was it the first time cruising in that high speed? If it was, the oil needed to lock up the converter probably was the "last drop". The lock-up typically happens in just that speed. If cruising at "constant" speed, you won't even necessarily notice it. Drops the revs a couple 100 rpm.

[HenrikGM]

It wasent the first time at that speed, but maybe the first time is was cruising there.

The lockup AW71L apparently is recognised by only one plastic grille in the converterhousing(tjeck) and by having square "threads" welded onto the back, (also tjeck).

Tomorrow i will top it up to before, and add a bit more, and see if it ends at your static cold level. Maybe the whole issue is just oil level, allthough that will puzzle me a bit...

[HenrikGM]

Hrmm, the plot thickens...

Topped it up to 1cm above the plastic. Started the car, was pulling fine initially in all gears, then after some 40seconds it again lost drive completely. Leaving it resting will restore drive in a few minutes.

Oil level was now more steady, staying 1cm above at idle as well as stopped.

When the pull disappeard there was a distinct "dull whining" like if a highspeed pump is cavitating. It lasted some 10seconds, and then went away. It then came back after 2minutes of idling, approx 10seconds.

Think im going to drain the oil in a clean white container and let it settle to see how it looks, then check the oil strainer. I would be surprised if it allready clogged the filter though.

Any good things to check, ideas, etc, are much appreciated.

[mauser240]

I would try more oil first.

But. If you have a stable, high stick reading when power is lost, then it probably won't help.

Is the stick still reading the same with engine shut?

Whining noise sounds like pump runs out of oil. Maybe it's time to check the filter hasn't come lose, like somebody already suggested.

[HenrikGM]

gearbox level stays approx 1cm above plastic. In total i have added around 6,75 liters to the gearbox now, this should be way more than needed(The converter was not drained)

Have spent a good hour creating the special fitting needed to record line pressure.

Pressure is reading 4bars in idle. Rapidly drops to near zero when the drive dissapears. will do a bit more testing to record this behaviour.
Apparently the gearbox is loosing all oil pressure....