MY fluid in my auto is light brown I was wondering if I should change the filter and fluid? If I do should I drain the convertor too? I think they hold most the fluid. I also heard changing fluid can damage tranny (YIKES) What should I do? Car still shifts good but worried about browning fluid and filter being never changed a bad thing!
Auto Tranny Question? Change brown fluid?
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Brown fluid is a sign of things going bad inside your trans. the fluid turns brown because its been overheated. At the very least, you should drain everything and change fluid, filter and give everything the once over. Put an aftermarket trans cooler on that thing before you burn it up.
Changing the fluid will not f up your trans, not changing is probably what got you were you are.
Changing the fluid will not f up your trans, not changing is probably what got you were you are.
Mustang John
Founding Member
Changing fluid is "most always" a great idea... BUT, if the fluid is really fried, you may change the fluid, and the car may finally take a dump...
The clutches continually shed material. After a certain point, they will slip a bit, especially with old crappy fluid. That induces heat. Once the the clutches get really varnished up from the fluid overheating, you change the fluid to some nice slippery thicker fluid, you may have troubles...
Brown, may just be old and fine to change. If it smells burnt and is dark, you may notice troubles after a fluid change. If it does, then it was bound to happen eventually. But, you may have sped up the demise with the change.
We certainly get a few cars in from the local lubestops that came in with fried fluid, they changed it, and it would hardly pull out of the place.
If it comes in with really burnt fluid and still moves ok, we tell people to eek out the last days of it, and save for a build.
This not to tell you not to change the fluid. But, to warn you what could happen if it's really toasted.
Ahhh okay. MY fluid is about the color of new oil inside a car. Very light brown. I Put some slick 50 in there to help it out so ill go ahead and do a fluid change. Its worth a shot.
Thanks for all the info. Can everything be drained without dropping tranny? Ill take a guess ya need to remove the cover under car and there should be a drain plug on convertor. Once drained out do I need to put fluid in convertor or just in tranny dipstick area?
Thanks man!
Thanks for all the info. Can everything be drained without dropping tranny? Ill take a guess ya need to remove the cover under car and there should be a drain plug on convertor. Once drained out do I need to put fluid in convertor or just in tranny dipstick area?
Thanks man!
Mustang John
Founding Member
AODs shouldn't have a drain on the converter. Drop the pan carefully, so you don't take a bath, and swap the filter and replace the gasket. Fill through the dipstick tube. You won't get what's in the converter though.
If it's just brown and not nasty smelling, it's probably just old and not burnt.
Not a fan of the slick 50 or any of the misc additives for the most part. They usually just swell seals and do things that aren't needed. Good old straight ATF.
We do use two things that free sticky valves or are a friction modifiers for certain apps made by LubeGuard, red protectant or black friction modifier. We don't use them unless we have to.
If it's just brown and not nasty smelling, it's probably just old and not burnt.
Not a fan of the slick 50 or any of the misc additives for the most part. They usually just swell seals and do things that aren't needed. Good old straight ATF.
We do use two things that free sticky valves or are a friction modifiers for certain apps made by LubeGuard, red protectant or black friction modifier. We don't use them unless we have to.
Ahhh okay so im taking a guess here that convertors are self oiled and do not use the same fluid line as from tranny? Guys at Autozone told me when I was doing my rear main and dropping tranny as long as I didnt pull drain plug on convertor id be okay as to not have to put a crapload of fluid in. There not tranny guys though so hehe.
So the only fluid I need to change is pan fluid(good thing) lol.
Yeah it doesnt have a nasty smell no real smell at all. Thanks for the help! I was alittle scarred there lol.
So the only fluid I need to change is pan fluid(good thing) lol.
Yeah it doesnt have a nasty smell no real smell at all. Thanks for the help! I was alittle scarred there lol.
Mustang John
Founding Member
No, the converter shares fluid from the trans. You will still have some old nasty fluid in there after your change unless you drop the trans and drain the converter. 
Only certain converters have drain plugs. The AOD is not one of them.
Only certain converters have drain plugs. The AOD is not one of them.
hmmm,
Well that does suck becuase then it would still have that nasty old tranny fluid in there. They need a flush machine like the oil flush lol. So they could flush the old out without having to drop tranny!
Would make it easier! Not draining out of the converter would mix old with new and I cant see how that would help. Changing the filter would help of course but the old tranny fluid full of particles would just over power then new fluid...
Never easy lol.
Well that does suck becuase then it would still have that nasty old tranny fluid in there. They need a flush machine like the oil flush lol. So they could flush the old out without having to drop tranny!
Would make it easier! Not draining out of the converter would mix old with new and I cant see how that would help. Changing the filter would help of course but the old tranny fluid full of particles would just over power then new fluid...
Never easy lol.
Mustang John
Founding Member
They do have the trans flush systems like you mentioned for the oil... I don't feel that they'd do any better if at all, they just basically eliminate the need to drop the pan. They just add new fluid into the old till it runs clean looking.
Still leaves a lot of old fluid mixed in with new fluid. They do at least flush it out of the cooler too. Maybe worth a looking into I spose.
We just drop the pan and swap fluid and filter and accept some of the old stuff staying in there as a sad fact of life.
Still leaves a lot of old fluid mixed in with new fluid. They do at least flush it out of the cooler too. Maybe worth a looking into I spose.
We just drop the pan and swap fluid and filter and accept some of the old stuff staying in there as a sad fact of life.
Drain
AOD converters (should say most converters) do have a drain plug. You remove the cover plate on the front lower side of the bell housing that you would remove to gain access to the converter attach. hardware. You can remove a small plug thru the flex plate to drain the converter. The plug is located next to one of the converter attach (bolt or stud and nut) points. Just bump starter till plug is on the bottom remove and drain.
The converter fills from trans pump so it would be wise to bump it around after it is drained so the drain plug is facing the Lt side of the engine at the top of the access plate opening and pre-lube converter for the initial start. (3/4 to 1 quart is good pre-lube).
I strongly advocate aux trans cooler spliced into the in radiator cooler. Your brown fluid demostrates why cooling is important and it will help trans handle great power and last longer which makes the $30 bucks well spent.
The fluid should go into the aux cooler first and then through the radiator tank cooler before returning to the trans, if you live in cold temps to prevent over cooling the fluid which is just as bad for the trans.
I agree with adding a drain plug or using a pan with one to ease service because if it is a pain to do it gets done less often! AMSOIL race fluid (although a tad pricey) provides nice firm shifts and has all the bene's of being fully synthetic.
AOD converters (should say most converters) do have a drain plug. You remove the cover plate on the front lower side of the bell housing that you would remove to gain access to the converter attach. hardware. You can remove a small plug thru the flex plate to drain the converter. The plug is located next to one of the converter attach (bolt or stud and nut) points. Just bump starter till plug is on the bottom remove and drain.
The converter fills from trans pump so it would be wise to bump it around after it is drained so the drain plug is facing the Lt side of the engine at the top of the access plate opening and pre-lube converter for the initial start. (3/4 to 1 quart is good pre-lube).
I strongly advocate aux trans cooler spliced into the in radiator cooler. Your brown fluid demostrates why cooling is important and it will help trans handle great power and last longer which makes the $30 bucks well spent.
The fluid should go into the aux cooler first and then through the radiator tank cooler before returning to the trans, if you live in cold temps to prevent over cooling the fluid which is just as bad for the trans.
I agree with adding a drain plug or using a pan with one to ease service because if it is a pain to do it gets done less often! AMSOIL race fluid (although a tad pricey) provides nice firm shifts and has all the bene's of being fully synthetic.
Getting the trans profesionally flushed is a must. Just droping the pan does not do it. Some like to do the flush and then drop the pan and replace the filter. Even better. The fluid should be pink/cherry red afterwards. An aftermarket cooler is also a must. It will make it shift better, and last longer.
a good tranny flush will get all the old fluid out and replace with all new fluid. some shops will cut the flush off whenever they're tired of waiting for it, or not keep flushing till its clean.
i've been told its a bad idea to just drop the pan on an auto if the fluid is brown and shot, because new dextron/mercon/ you get the picture is basically a 5 weight motor oil with many additives and detergents. these break down dirt that is in your trans valve body etc. and when your fluid is brown its an indication of possible build up in there. when its broken down, it could clog the filter or valve body etc. dont know how much truth there is behind all that, but it kinda makes sense.
also been told changing some is better then none. so i've heard both sides. take it for what you will, just thought i'd share.
i've been told its a bad idea to just drop the pan on an auto if the fluid is brown and shot, because new dextron/mercon/ you get the picture is basically a 5 weight motor oil with many additives and detergents. these break down dirt that is in your trans valve body etc. and when your fluid is brown its an indication of possible build up in there. when its broken down, it could clog the filter or valve body etc. dont know how much truth there is behind all that, but it kinda makes sense.
also been told changing some is better then none. so i've heard both sides. take it for what you will, just thought i'd share.
The Shape
Founding Member
Don't know how much good it does, but last time I serviced mine I stuck a magnet in the bottom of the pan to hopefully catch any metal shavings floating around.
With engines, the motor oil provides lubrication, and the coolant dissipates heat. On automatic transmissions, the ATF has to serve both duties. It lubricates AND it dissipates heat. The additive packages that go into modern ATF break down over time, especially if the fluid is over-heated.
When I bought my 89 LX earlier this year, it had 69K miles. The car was in great shape, but it was obvious that the trans fluid had never been changed. It was brown and had a slight burnt smell to it. I dropped the pan and replaced the filter.
If you do this yourself, make sure you have a grinder to grind off the old pan gasket. Mine was the original one, and was totally stuck to the pan.
You also want to make sure that the transmission service kit you get has the small, square, cork gasket that goes on the filter. When I was at the parts store, I picked up a transmission pan magnet and put it in my pan to catch any metal particles.
After doing the pan-down service on the transmission, I did a transmission flush (we have the machine at my shop.) I had to flush about 28-30 quarts through the transmission before the fluid came out looking and smelling clean.
I couldn't believe how much better my AOD shifted after this service.
Sam in Denver
When I bought my 89 LX earlier this year, it had 69K miles. The car was in great shape, but it was obvious that the trans fluid had never been changed. It was brown and had a slight burnt smell to it. I dropped the pan and replaced the filter.
If you do this yourself, make sure you have a grinder to grind off the old pan gasket. Mine was the original one, and was totally stuck to the pan.
You also want to make sure that the transmission service kit you get has the small, square, cork gasket that goes on the filter. When I was at the parts store, I picked up a transmission pan magnet and put it in my pan to catch any metal particles.
After doing the pan-down service on the transmission, I did a transmission flush (we have the machine at my shop.) I had to flush about 28-30 quarts through the transmission before the fluid came out looking and smelling clean.
I couldn't believe how much better my AOD shifted after this service.
Sam in Denver
Mustang John
Founding Member
I must have been mentally elsewhere in my post, I've even drained these converters in the car and I still said that...
I'd have to say though, that if you're going to get it all out, I'd do the fluid flush and then still do a pan drop, drain the converter and do the filter while there. Flushes don't totally do it, and pan drops don't totally do it either. Do both and it's as good as it can be. Flushing first will blow stuff out of the cooler getting it cleaned out and then do the pan drop to get the material in the pan.
Still, only do the change if the fluid doesn't smell burned or have a smoky smell. Dark or brown is less likely to be a problem, but black and/or burnt smelling is a bad sign, and unfortunately you should probably leave it till it quits working right.
I'd have to say though, that if you're going to get it all out, I'd do the fluid flush and then still do a pan drop, drain the converter and do the filter while there. Flushes don't totally do it, and pan drops don't totally do it either. Do both and it's as good as it can be. Flushing first will blow stuff out of the cooler getting it cleaned out and then do the pan drop to get the material in the pan.
Still, only do the change if the fluid doesn't smell burned or have a smoky smell. Dark or brown is less likely to be a problem, but black and/or burnt smelling is a bad sign, and unfortunately you should probably leave it till it quits working right.
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