Overdrive left off, black tranny fluid question

[williamprowse]

1987 Toyota horizon 22ft 22-re EFI

The previous owner told me that the overdrive must be turned off while driving in town, and when on the highway, you turn it on. I found out that it should have been on all the time, unless there is a special circumstance. 

So I drove with the overdrive off for about 3000 miles. Did turn it on here and there for highway, but not all the time.

Now the fluid is black. I drain and filled twice and filled it up without over filling it. Still black. Improved color, but surely still black. have used shop pump to take out as much as possible. Also ran for 10 seconds to get as much fluid out as possible.

It shifts smoothly and works well from what I can tell. No issues there besides the black fluid.

Should I be concerned? Any comments would be greatly appreciated! 

[linda s]

Have no idea why the fluid is black but it has nothing to do with overdrive being off. Possible the heat generated by being on all the time could have dissolved some seals and takes more than a couple of changes to clear out all the gunk. I never use overdrive and in 60,000 miles my fluid has never turned black. Change my fluid at least every 2 years and at the most it's slightly browner but still very red. The constant shifting back and forth when overdrive is on can cause heat build up in the tranny and do damage

Linda S

[WME]

Unless there is a LARGE external transmission cooler on you rig, you will overheat the fluid when you use the OD. That can turn it black/dark brown

The OD was designed for use with a 3000lb pickup and not a 6000lb high drag RV. Most of us NEVER use OD.

[Maineah]

If it's working OK don't play with it you may end up killing it but yes a bigger cooller won't hurt.

[Derek up North]

It doesn't sound like you're dropped your pan and cleaned out any sludge that might be in it. This would probably go a long way to getting your ATF back to a good colour.

[williamprowse]

Was at work all day and this is new account because forgot password to old account on here.

Thanks for advice! Good to know. I was thinking that pulling a full loaded rv (I have a huge battery bank, much to big for it, and two propane tanks. I live in it full time) could cause the fluid to change. I also did some pretty steep climbs (slowly) with it loaded. I am amazed these little guys can do what they do. 

Maybe a flush will do it. I will keep overdrive on from now on. Have been checking fluid often, so hopefully will avoid future problems. I hope! Lol

[Maineah]

The problem with high mileage trans fluid and fresh fluid it has a tendency to dissolve the stuff that's on the clutch plates and with high mileage that's the only thing that is protecting them. Then all that gunk ends up in the valve body and what's left of the clutch plates are worn off. In theory it should be changed every 30K and with the MH it is considered severe service.  If it has been changed regularly you can continue to do so until it quits moving but if it’s never been touched with lots of miles you’re asking for trouble.

[williamprowse]

Wow good to know! Very good to know. I had no idea!

[WME]

If you installed a full depth external filter you might get away with a full flush. But the stock Toyota filter is just a bug catcher and big stuff ends up the valve body..

[Maineah]

The only transmission that had a real filter was Chrysler they would plug up then the vehicle would stop moving. A good filter will stop more stuff but it won't prevent clutch damage (by the way that is an all clutch trans it has no bands) from all new fresh fluid.  They are tough transmissions and with a little care will last 150K+ but the care should have started at about 30K.

[DanAatTheCape]

If I had black tranny fluid I would be concerned.   My toy (93 winnie warrior) specs dexron II which is red.   Tranny fluid is a hydraulic fluid which will break down if overheated - can't recall the temp range but I seem to recall that a little over 300 is when things get critical. 

 

If I had your machine I would drop the tranny pan, change the "filter" (it is really just a screen)  and look for magnets to see if they collected any metal particles - expect to see some "dust" on them.  

 

TO change ALL the fluid can be done 3 ways   1) remove a hose going into the tranny cooler (bottom of radiator - or external cooler if you have one), run the engine measuring what comes out - say pint by pint and adding the same amounts as you go.  I think this is a 10 qt system - you will need 3 to 4 gallons to do it. 

2) use an engine flush procedure ( I would NOT do that - these procedures can break lose minute bits of gunk which can clog the small orifices and that will require a tranny shop/ overhaul)

3) Change the fluid in the pan (about 2 qts).  Drive the unit and replace the 2 qts (my unit has a drain plug on pan).  Repeat until you go through 3 gallons.  Every time you do it you will change less and less old fluid and more and more new fluid.  This is the least risk option.

 

If you do not have an external tranny cooler you might consider - sounds to me you really overheated your tranny and that can get real expensive real quick.  The high load slow speed operation regime of these toys can cause serious problems. 

Some folks add a tranny temp gauge to the outside of their tranny so they can monitor the temps

 

 

[DanAatTheCape]

http://www.tciauto.com/tc/trans-life-expectancy/   found this googling ATF temperatures

if you google "atf temperature gauge"  you will find a lot of options.   Some can be installed with out intruding into the tranny 

 

[Maineah]

Trans fluid is clear it has a red dye, the black is old fluid and clutch bits all pans will have some metal in them (brass and aluminum) it's the silver stuff that you need to worry about if there is mud looking stuff in the pan it's clutch material and you should start saving money. If there is no air cooler you need one. You can change the fluid if you want but do it in steeps  a LITTLE bit at a time do not do a full flush or you will be walking in about a week. A temp gauge in a Toy Home will drive you nuts they will get hot and there is not a lot you can do about it except use a lower gear. Pretty much any  motor home needs the fluid to be changed every 30K it's not just Toyota all motor home transmissions take a beating. My Toy home when I bought it had 28K on it the fluid was brown I did a full flush because of the low mileage the new owners will do it again at 60K and I'm pretty sure it once again will be brown.