This afternoon for the 2nd time, my A/T light has come on but quickly go off almost right away. I've been doing some researching and came up that I may need to do a tranny flush or just drain the oil in my tranny. I know not all of the oil doesn't get drained but again I read that a tranny flush does more harm than good. My 4Runner is a '91 with almost 340,000km on it, bought it from the original owner about 6 months ago, so I have no idea if he has ever changed the tranny fluid. Any help would be greatly appreciated.

Thanks,
Freddy


***My tranny doesn't slip, there's no harsh shifting...everything is smooth as butter.

 

http://www.gadgetonline.com/TransFlush.htm
http://www.amsoil.com/faqs/ATF_and_F...Procedures.pdf

 

Good info in the first link on why not to flush.

 

In my experience and from what I have been told/read if you flush your trans within the first 35-60k mile (depending on manufacture recomended intervals) you will be fine. If you have a lot of miles on your trans and flush it you actualy flush the clutch and other wear particals out with the fluid. Those particals are helping your trans grip the clutchs and what not. If you change it your trans will start to slip. I have made that mistake a few times in the past! Its a very expensive mistake!

 

No slipping, shifts smoothly, that's great. Which A/T light is coming on? My Runner has an A/T High Temp light and an OD light. Chances are the light flickering is one of two things, it's overheating or it has a solenoid going out. Could be as simple as a loose wire connector on one of the solenoids or overfilled fluid. These are easy fixes.

How about the fluid? Is it bright and pink and clean smelling, or brown and foul smelling? If brown, get it out of there ASAP and do the full flush. You can't hurt the tranny any more than it is already damaged! And, by the way, this is an Aisin transmission and a very strong and reliable unit if maintained. There are very few reasons NOT to flush it, and that's only if the transmission is on its last legs and there are particles in the fluid.

However, on the 3.slo, if you have a head gasket going, it will overheat the trans through the transmission cooler which is inside the radiator. Be sure to check that out too.

 

^ Yeah do what that guy said and then let us know the results.

These people are all probably wrong

http://www.trustmymechanic.com/transslip.html

http://www.gottransmissions.com/blog...ntenance/flush

http://www.aa1car.com/library/2004/bf100456.htm

Just google "transmission slips after flush" and read the stories.

He doesnt know if it has been maintained, as he stated he just bought it 6 months ago. Pretty much every automatic is a strong and reliable unit IF maintained, unfortunatly most people do not maintain thier vehicles the way that they are supposed to.

 

Sure, James, read these blogs and my post again ... and the common factor is that the fluid had metal in it. The damage to that transmission is already done, it's only a matter of when it's going to fail.

Ultimately it will come down to a judgement call, no doubt.

 

I apoligize, I dont mean to sound like a dick, I just have lots of experiences with cars that drove fine, get a trans flush at Jiffy Lube and get towed in because the transmission now slips. You are right though, it does come down to a judgement call and in the end it is not really our call to make as it is not our rig, we all will have our own strong opinions based on our own experiences and when it comes down to it, all we can do is supply the OP with info to make the call themselves.

 

The bad thing is, we (mechanics too) only hear about the people that have "bad" experiences when doing a tranny flush.

I have done flushes on two high mileage trannys and have not had a problem. So am I the exception or the rule?

 

Not like it really adds much to the discussion but I just flushed my AT with 250k miles last weekend. So far it is doing great.

 

Well the thing is, when you are a mechanic, things are differant then working on your own car, when you hear of transmissions going out after a flush and then one comes in that wants a flush, the way the auto industry is, when a technician see's the mileage and then pulls the stick and see's dark fluid, they just turn it away and refuse to touch it. I have turned away many cars that were modded and wanted work done to it, just for the fact that if anything goes wrong on that car from the mods, I "own" it and have to fix it for free and it comes down on me. That is one reason, I hate working in the automotive field and the flat rate pay structure.

 

You can do a tranny fluid change and filter change without powerflushing it. Although not all of the fluid gets out you end up getting a good percentage of new clean fluid. I prefer not to take the chances of power flushing especially since they don't change the filter. Also while the pan is down you can clean all the metal off the magnets in the pan so they can pick up some more metal pieces.

Of course it would help to know what light is coming on.

 

The light thats comes on is the A/T Oil Light, its red i believe. I checked the fluid its clear/pink...looks clean. Seems to be full too.

 

What type of driving were you doing when the light came on? Sitting in traffic or driving down the highway on flat ground? Towing or going up a steep hill? Like previously said, the trans cooler is in the radiator so if the cooling system is not cooling effectivly from a blown headgasket or low coolant, it will affect the trans fluid, also from what I understand is if the trans fluid is overfilled it will trip this light also. If the transmission has been recently replaced and the cooler wasnt properly flushed out it could be restricted.

 

I talked to my tranny guy about this with my last truck, which had 230000km on it. He said the tranny needs to be flushed at least a few times in it's life. I did mine just after that, put in synthetic fluid and it was working like a charm when I sold it at 270000km.