Auto Trans Service

[dave88]

I recently got an 85 4wd with a 3 speed auto. At first the kickdown didn't seem to work, but improved after driving it relatively hard for a week. It works but doesn't seem to stay down quite long enough. Anyway, it seems to drive and shift pretty good. But I know with a tranny like this if the tranny goes the car probably goes.

So I'm thinking I might want to do some preventative maintenance?

I'd like at least replace the fluid. I've heard horror stories of draining an old AT only to dislodge something and make the tranny worse. Is this a likely problem with these? Should I try to siphon fluid out the dipstick? Or maybe I should just leave it be?

[splatterdog]

Draining and filling is harmless. It should have a drain plug. I would drain and fill during engine oil changes until the fluid stays new looking.

If fresh fluid kills a trans, it had it coming. They for sure won't last without fluid maintenance. The naysayers are usually the ones that waited till the trans was acting up before changing fluid.

Make sure you check linkages too.

[Petros]

Good advice. Change the fluid, and check the linkage adjustment (off the throttle plate). Also I have had good luck with the trans additive designed for cleaning out the sludge from an autotrans. My daughters '86 CRX was slow to shift (shift at high rpms during normal driving), I put in some Seafoam trans additive, with new fluid, and it cleared the problem up. The valve bodies get sticky with old gunk and sludge, the additive cleans it out.

If your seals are good in the trans I would avoid the additives that have "seal conditioners" in them as well. These soften old hard seals, and if your seals are leaky worth a try. But if the seals are good I would not want to soften them if they do not need it, it will shorten the seal life. So look for the additive that will clean out the valve body without the seal conditioner in it, unless you want to soften your seals.

There stories I hear of fresh fluid in an old trans "causing" a trans failure are just folk lore and shade tree mechanic advice. If the trans is good, new fluid will not cause it to fail. If it was going to fail, changing the fluid will not cause or stop it from failing. Splatterdog got that one exactly correct.

[splatterdog]

Here's a good additive. http://www.lubegard.com/~/C-112/LUBEGAR ... Protectant Do not use any of their friction modified automatic additives. That's for fussy modern tranny's.

Good stuff from them in general IMHO. Fixed a few noisy/jerky Ford power steering systems with their flush and protect pack.

[takza]

Here is what I would do....

http://www.tercel4wd.com/forums/viewtopic.php?f=7&t=63

[animeracing]

Good preventative maintenance would be buying a case of your preferred ATF (synthetic is good) and a AT filter kit, then draining the tranny, dropping the pan, changing the filter out (or just cleaning it if the OE one is in good shape and better quality than what you bought), add new gasket and bolt on the pan, fill tranny to spec, (checking fluid level once warm after driving too), then change out the fluid once or twice more in the next few weeks/months to completely swap out all the old fluid for the new.

I wouldn't suggest a pressure flush for an all-at-once fluid change. That's where you CAN get some real problems, especially depending on who's doing it and how well they really know what they're doing. There is some truth to the grit and particles in old ATF getting drained out and then a worn tranny starts slipping story, but if you change out the fluid sooner rather than later, you won't have that problem.

[splatterdog]

Tranny flush is kind of a wrong description in most cases. Most good machines(like mine) are exchangers. They are passive and the trans does all the pumping thru the cooler lines.

[dave88]

Thanks for the great tips guys.

Is there any danger in doing the method takza describes in his link. Letting the engine idle in park, and draining the fluid at the radiator?

[splatterdog]

The biggest problem is filling the trans as fast as it pushes the old fluid out the cooler hose. I prefer the trans oil pump to not suck any air. Have a friend on the ignition key while you get messy.

[4wdchico]

Thanks for the great tips guys.

Is there any danger in doing the method takza describes in his link. Letting the engine idle in park, and draining the fluid at the radiator?

Yes. Don't do it. If you set up a tank, several feet in the air, to gravity feed the return line of the tranny cooler with fresh ATF while allowing the tranny to pump the old fluid out the other cooler line, that would be OK, or at least a bit better. That would be exchanging the fluid, not running the tranny low.

The low tech option, & a whole lot simpler/cleaner, is just to set up an overnight siphon thru the tranny fill/dipstick tube into a big bucket. Then just replace the same amount as drained with fresh ATF. Do that a few times over several months of driving and your tranny will be nice and clean inside.

Whenever possible, I make sure that any engine/trans/diff/transfer case of mine has a magnetic drain plug. A magnet will catch fine ferrous particles that no filter can catch.

[splatterdog]

4wdchico- wouldn't draining and filling be easier than a tube siphon?

Drain,fill, repeat as necessary for the low tech method. You will dilute all the old out eventually. Do as many times as it takes over a week or two until it stays new looking. Then just drain and fill at every other oil change. If you pull the pan, putting a magnet on the bottom in a safe place is a good idea. Even putting one on the outside can help.

Back in the day before trans flushers were around,I did several cooler hose flushes(takza style) without incident. The biggest problem was the potential for a big mess.

You could always come to Mn. and have me flush it. My machine does an 18 quart exchange.

[4wdchico]

4wdchico- wouldn't draining and filling be easier than a tube siphon?

Drain,fill, repeat as necessary for the low tech method. You will dilute all the old out eventually. Do as many times as it takes over a week or two until it stays new looking. Then just drain and fill at every other oil change. If you pull the pan, putting a magnet on the bottom in a safe place is a good idea. Even putting one on the outside can help.

Back in the day before trans flushers were around,I did several cooler hose flushes(takza style) without incident. The biggest problem was the potential for a big mess.

You could always come to Mn. and have me flush it. My machine does an 18 quart exchange.

Lots of folks are pretty adverse to doing the drain the tranny pan drain thing, not sure why. That and a lot of tranny pans have no drain plugs. So I often suggest to folks that they can also do the overnight ATF siphon. I also run the paper filter & magnet inline filter on any auto tranny of mine. The C6 in my '85 F250 diesel, my only auto trans at the moment, has had a bunch of siphon drains over the years as it has no pan plug. That and a new inline filter/magnet every year & it is very happy. I pulled the pan and changed the filter a few years back and the old filter was perfectly clean.

[splatterdog]

I always wonder why domestics don't have trans drain plugs. Seen some on newer fords and chevs but a couple years later they disappeared(less parts=more profit). The Japs put drain plugs on everything! I have a fluid evacuator for the ones that don't. Makes pulling the pan much less messy. No more "tranny splashes" for me.

Did you know that your C6 torque converter likely has a drain plug too? All my C6's had them. Actuall every old Ford I owned had them. I'm not surprised it's still a happy trans. They are very tough. But also take the most horsepower of any 3 speed to operate.

[4wdchico]

I always wonder why domestics don't have trans drain plugs. Seen some on newer fords and chevs but a couple years later they disappeared(less parts=more profit). The Japs put drain plugs on everything! I have a fluid evacuator for the ones that don't. Makes pulling the pan much less messy. No more "tranny splashes" for me.

Did you know that your C6 torque converter likely has a drain plug too? All my C6's had them. Actuall every old Ford I owned had them. I'm not surprised it's still a happy trans. They are very tough. But also take the most horsepower of any 3 speed to operate.

Yes, I have heard about the power loss. There are a several boutique tranny shops that specialize in the C6 and they pretty much all claim that they can reduce the frictional/pumping power losses dramatically by putting a bunch of roller bearing thrust washers in and a few other mods. If it ever fails, long odds on that, I guess that I will go the update route.

Honestly, I never gave the draining of the TC much thought. Guess that I figured that I was over killing the tranny maintenance enough.