ATF and filter question

[GSP]

My 1009 shows 60k on the odo. I checked the atf yesterday and its barely showing on the dipstick. What little is on there is black and smells awful. Naturally i want to change it and the filter. A few people have said it may be a bad idea. Something about the friction material from the clutches being in the fluid. They're saying if i change it that it may start slipping. Any truth to this? And if so what should i do?

 

[Warthog]

When the new fluid is installed it flushes the system and can cause slippage. I have had it happen to me. If it is that bad plan for a rebuild in the future.

 

[Bob H]

Change the fluid & filter.
If it starts to slip it's because it needed to be rebuilt.
You didn't drive it with "its barely showing on the dipstick."
running them low on fluid is a real quick path to a rebuild.

 

[Coffey1]

I had a Chevy pickup the fluid was full did not look bad so trying to be proactive on my new old truck changed all fluids .
Drain transmission new filter refill never moved again.
Had to replace it.
It can happened drain it and get new transmission.

 

[TXFirefighter]

If the fluid is dark and burnt smelling it means the transmission has been over heated and worked hard.
Clutch material wears and is suspended in the fluid. As seals age and start to seep, this clutch material starts to pack into the sealing area and "plugs" the leak thus keeping the trans moving.
ATF is highly detergent. When you change the fluid and filter, the new fluid washes the old clutch material out of the seals and ........ Over haul time.
If transmissions are serviced properly, the new fluid additives help keep the seals pliable and in good shape. I advise my friends that IF they have over 60K miles on their vehicle without changing fluid before, then DON'T change it.

For you, I would suggest you just add what is needed to bring the fluid level to the correct level and leave the thing alone.

 

[cucvrus]

I have to agree you have reached the point of no return. Top off the fluid and run it like you stole it. It may last 5 years or then again it my last 5 minutes. It is defiantly living the golden years and I see an overhaul in the near future. And a word of advise if I may? DO NOT buy a used transmission and go through trouble of putting it in. Any take out transmission you buy is questionable. I do not take used transmissions out of these vehicles anymore and sell them. I sell them as cores and exchange units. I have had my share of used transmission problems. They never win any friendships. I have a few trucks that have been sitting for 7-10 years, they have low mileage but I would not just pull the transmission and put it in another CUCV. I had a new one from a GM military steel box that had no reverse when I installed it. That was it for old transmissions. Do as you wish. But I think if I were you. I would be saving some money for an overhaul on that transmission of yours and don't overwork it. That just compounds the problem. Good Luck. The TH400 is one of the best automatic transmissions in the world. It has been used for 50 years and holds up well under severe and high performance use.

 

[cbear]

I know nothing of the CUCV, but I am a big fan of the remote transmission filter kits, that use a spin on oil filter. The B&M 80277 is what I have used. A slightly easier option is a magnefine transmission filter, but subsequent filter changes aren't as easy. The in pan transmission filter is about 100 microns filtration, and a basic oil filter is about 20-30 microns depending on what filter you pick. This will do a lot to clean up the existing fluid, if you chose not to change it. Burnt fluid has lost some of it's lube properties, so I would do a drain and fill, but it's not my truck.

 

[Chaski]

I have to disagree with the advice to top off and run it. Sticking your head in the sand isn't going to increase your confidence to take the rig on a long trip. The transmission needs good flow to the pump. Low flow means low pressure on the clutches. Low pressure on the clutches means they slip and your transmission self destructs. Drop the pan, check for pan treasures replace the transmission filter and fill it back up if you don't find chunks of friction material. A gasket, filter and a few quarts of ATF are all you need. At least with a new filter you are giving the transmission a fighting chance.

 

[KsM715]

I used to think that old tale was " hog wash", till the last Jeep I bought ('99 TJ) I had the tranny flushed and sure enough it started slipping.

Drop the pan, change the filter and re-fill with fresh fluid but do not let someone talk you into flushing it out.

 

[MarcusOReallyus]

I used to think that old tale was " hog wash", till the last Jeep I bought ('99 TJ) I had the tranny flushed and sure enough it started slipping.

Drop the pan, change the filter and re-fill with fresh fluid but do not let someone talk you into flushing it out.

"Flushing" at a shop usually means a high-pressure flush with a machine made for that purpose. It can knock crud loose and plug passages. Bad stuff. Stay away from it.


On the other hand, replacing ALL the fluid can save a slipping trans. It can't hurt it. Speaking of Jeeps, I did this 25,000 miles ago with mine, and it's been fine since. The fluid looked like old motor oil, smelled burnt, and the trans was slipping like crazy every time it got good and warmed up. Not overheated, just well warmed (like an hour of driving). When I say slipping like crazy, I mean limping it to the nearest safe place to get off the road, hardly able to get moving. Most people would have written that transmission off.

To replace all the fluid, find the cooler line that comes FROM the transmission. Cut it at a convenient location. Stick a piece of rubber hose on it to direct the fluid down into a drain pan. Have soldier B standing by to start the engine, and soldier C watching the fluid going into the drain pan. Get yourself ready with a good funnel and a couple of gallons of trans fluid. Have soldier B start the engine while you start pouring fluid into the fill tube. Keep going until solder C says the fluid is coming out nice and clean. Have soldier B shut off the engine. Use a short piece of rubber hose and a couple of clamps to repair the cut in the cooler line (it's low pressure - it will hold just fine), and then make sure your fluid level is good.

Done.


It's cheaper than a rebuild. The worst it can do is trash the trans, and if it's trashed already, what have you got to lose? It's worked for a lot of people.

 

[Bob H]

The only flush systems I've seen do not use pressure, other than the transmissions pump.
The trans cooler lines get connected to it and as the old fluid pumps in, it pushes the new fluid into the return line, once clean fluid is observed pumping out, you shut off the car & reconnect the lines. Then I like to drop the pan & change the filter. Sure it costs more but all the fluid is changed this way.
I have never had a trans go because the fluid was changed, it just doesn't work that way.
Back 30 years ago when I did repair work on the side, my trans guy used to say "if everyone changed their fluid & filter annually, just about every trans rebuild shop would go out of business"