I had to go on a mission of mercy tonight when my son's 240 wouldn't get him home from work. It's an auto/AW70 transmission and at first I thought that it was low fluid as it leaks a bit. I checked the level with the car not running and the gauge was dry so I dumped in 2 quarts and then ckecked again (it was a long day) and wamo....lots of fluid now. He has said that it was slipping badly when he tried to drive it but it seemed to be working so we headed for home. We didn't get very far when he pulled to the curb and said it was slipping again and so I drive it and sure enough it slips very badly when it goes into third. 1, 2 and R seemed to work Ok so I told him to try leaving it in 2 and keeping it to about 35. This worked and we made it the 12 miles home. The transmission has always been OK until now, but is this the death rattle? Is there any fault finding i can do or is this just get a new trany time? Any helpful advise would be highly appreciated.

Thanks,

Cliff

If I'm preaching to the choir, disregard this post.

When checking the transmission fluid level, it is absolutely important to check it with the engine running (at idle) and after having driven it at least for 5 minutes (for the cold side marks to be accurate).

If I were looking for a leak on an AW-70 transmission, I would expect that the most likely culprits would be:
1. Transmission cooler line to radiator, typically where both lines are clamped to the side of the engine.
2. Tailshaft bushing failing. When the bushing goes, it casues extra clearance/slop in the tailshaft oil seal and consequently looses fluid.
3. Transmission pan bolts loosening up and leaking fluid around the tranny pan gasket.

God bless,
Fitz Fitzgerald.
--
'87 Blue 240 Wagon, 258k miles.

Well it took nearly three quarts of DextronIII until it was finally showing the correct level when checked by the book. I am more used to manual boxes and I was not checking level correctly before, at temp, shift through all positions and running. At the proper level it drove fine on one long test drive. On a test drive later than day it slipped again going from 2 - 3 and would not engage. We drove it to a side street in second and stopped. When we restarted it shifted fine again. Son drove it all around town last night and it was good. Can this behavior be caused by old dirty fluid? Does this sound like a condition that a system flush could help?

Under the car the rear seal is leaking and the bushing has quite a bit of play. There do not seem to be any other significant leaks. The underside of the car wet round the tailshaft and the car will leave a few telltale drips, but no puddles so I am not sure how fast this is leaking.

I ordered the bushing and seal kit from FPG Groton last night and plan to replace the bushing and seals and then flush the system until I have good clean fluid.

Thanks to all for input and suggestions.


Cliff

Can this behavior be caused by old dirty fluid? Does this sound like a condition that a system flush could help?

I would assume that this condition is primarily caused by low fluid level, and then consequently air bubbles in the valve body and pistons. Given time, the air will work its way out of the system (usually within a few days at the most). However, I would strongly recommend a fluid flush if regular fluid changes have not been performed (4 quarts every 30,000 miles) or the transmission has been overheated or abused. You should notice a significant improvement in shifting with new transmission fluid.

Before changing the transmission fluid, you need to pull the transmission pan and clean out the sediment that is sitting in the bottom. The AW-70 transmission has a metal mesh filter screen which typically does not clog, but the worn clutch material does settle into the pan and collects on the pan magnets. (These magnets are undersized for the job and I advise adding another one or two before bolting the tranny pan back into place.) If you don't perform a pan cleaning, but flush the fluid anyways, the new fluid will start to look dark and dirty after about a week or two since the new ATF will start loosening up the sediment in the pan.

To remove the tranny pan, you will need a pair crescent wrenches with 12" handles (or longer) to loosen the dipstick tube. The rest is pretty simple, about 20 bolts holding the pan to the tranny. You don't need to replace the filter unless it looks visibly clogged or damaged, but you will need a new gasket for the transmission pan. You can order a complete kit (filter & pan gasket) from Napa for $20, or you can get just a pan gasket from Napa for $4 (they will have to order it and it takes about 3 days). The Napa pan gaskets are nice since they're made from rubber and can be reused if you have to take the pan off again soon. Budget yourself about 2 hours for a pan cleaning, and add another 3 if you're tackling the tailshaft bushing at the same time. You'll need to unbolt the transmission crossmember, tranny mount, and driveshaft to remove the tailshaft housing. Once the tailshaft housing is off, I'd advise a visit to a local machine shop and have them press out and install the tailshaft bushing for $10 if you don't have the tools at home.

One quick tip, when reassembling the tranny pan, put a dab of RTV on each of the bolt threads that hold the pan to the transmission. The transmission fluid, heat, and vibration can slowly loosen the pan bolts over time and a quick dab of RTV will hold them in place and prevent pan gasket leaks.

When flushing the transmission, disconnect one of the tranny cooler lines (that goes to the engine radiator) and flush out 2 quarts at a time. Buy aproximately 8 to 10 of the cheap $1 ATF quart bottles from your local AutoZone, etc, for your initial fush, and then flush in the quality ATF after that (about 5-8 quarts). Most people perfer to use Mobil 1 Synthetic since it does an excellent job in smooth shifting, reducing transmission heat, and clutch pack longevity.

God bless,
Fitz Fitzgerald.
--
'87 Blue 240 Wagon, 258k miles.
'88 Black 780, PRV-6, 148k miles.

As Kane said, recheck tranny fluid level and keep checking...Also check for a leaking tranny cooling line. A badly cracked or completely broken line could cause a fast leak. Can't think of anything else that might cause a fast leak. You really do need to locate any leaks ASAP.

If no leaks, definitely try a tranny flush before condemning the tranny.

Post back with anymore info.

G'luck,
Jim

--
90 244DL 255K - original engine/drivetrain :)

Have you rechecked the fluid? If there's a leak, that could be the reason why it slipped again.

-- Kane
--

While I would never deliberately mislead anyone, take into consideration that any information and advice provided was at no cost to you.

If you have no further leaks and your level is up where it belongs it is used tranny time or scrap the car. Rebuilds run in the 16-22 hundred dollar ballpark for a good rebuild. I have no doubt you can get it rebuilt cheaper but you will get what you pay for. Used trannys run around 350-500. If you pay someone to install it plan on spending about 4-5 hours labor at whatever the shop rate is that you go to. On a used box you had better plan on buying a few seals while it is out as well.

Mark