'99 camry trans. fluid greyish...

checked

for

re-filling

Automatic trans-fluid which has either been in service for a long time and/or has been subject to extreme service will collect band and clutch friction-material worn off those parts and hold it in suspension, thus changing its color.

One of the indicators for the need of an auto-service is ATF color-change.

Jason

If they do actually use a flushing machine it will extract a great deal of the old fluid in a shorter time and with less effort than the alternative, which is draining / filling / running engine repeatedly until fluid is red. The filter in your trans is a simple screen and can be cleaned easily (unless full of metal pieces from trans failure). Its not as critical to service as the more common filter types that trap dirt in a matted woven fiber element. But you do have to remove the pan if you want to clean it.

Toyota MDT in MO

I have had a lot of people tell me, after seeing this on the web, that the 'power flush' method of changing tranny sauce is a good way to kill a tranny! I know of 2 cars this has happened to; tranny was working but the fluid was dark, after flushing the cars went 100~1000 miles and the tranny went bye-bye. I have also had a tech tell me the same thing, and to just drain and fill, drain and fill every 500 or so miles until the fluid starts to turn red again. Maybe MDT Tech can shed some more light?

You can do a lot of partial drains and fills for $150! Changing the trans fluid every 3k oil change would get nealy all in 3 or 4 changes. Cost would be $10-20. While older yotas used Dextron2/3 newer ones (not sure year of the switch) use a different fluid (Type T). Dextron is bright red - what color is the new stuff?

The complete flush is better than just opening the pan as far as the fluid is concerned because you then get all of it. If you flush it out you will find that there is more to replace than the 2.5 quarts that's in the pan. This is because you're getting all of the fluid in the torque converter and everything else.

Some people will tell you that this has actually been a negative experience for them and that they've had a perfectly good working transmission fail on them after this change. From what I've seen, this indeed happens on 2 situations: 1) improper fluid used 2) or improperly refilled Read your manual and make sure that the dealer uses the proper fluid. Also after they give you the car, check the fluid level yourself. You'd rather that it be a little too low than a little too high. If the fluid is too high, there's too much pressure and you'll damage your valve bodies on it.

I have mine done on my cars all the time. I typically have it done every 50,000 miles. The only problem I had was once when it was over filled.

The T-IV fluid is also bright red.

would

as

them

cars

I agree that overfilling the transmission is not a good thing , but with all due respect , it does not 'increase' the pressure and damage the valve body. The pressure is controlled by the pump and the volume of oil does not change this. Overfilling however , causes the fluid to foam and aerated fluid can lead to heating and 'low pressure' problems. KD

Since you are a Toyota tech and I'm only a long time shade tree mechanic, I have a question to run by you if you don't mind. I'm rebuilding a 96 Camry 2.2 , 110 k , which had a water pump fail and caused severe overheating. So hot the engine quit. After pulling the pan and getting a peek at the bearings , I decided to do a rebuild. Anti freeze had made it's journey to the oil pan. :-(

I pulled the head and straightedged and it had .012 warp. The warp caused the cams to run too tight....so , I thought I would try honing the end journals on both the intake and exhaust cams. I used a horizontal honing machine with an exandable hone and took material from the journal cap, creating an egg shaped journal which is now .003 above service limit...on the cap.The cams run free after this. I also had a friend cut the head .016 to clear up the warp. You're probably raising an eyebrow right now , or maybe both. LOL but my line of thinking , which may be all wet , goes like this..

Incidentally , this will be my own engine , I don't experiment like this on others.

My thinking : Since the cams ride on the lifters , springs, all force is exerted upward and the 'slop' is on the bottom of the journal. Now , since the middle journals are well within limits I figure this will stop any wobble that could occur. There are at least 2 lobes on a lifter at any given time so there is going to be constant pressure upward into the area I honed. I could have used shims and accomplished the same thing , but , this is how it worked out. My biggest concern was the loss of oil pressure. A Toyota tech who is well respected here told me that would not be a problem since the amount of oil that gets to the end of the cam (cam is hollow and oils journals)is limited by a restricted opening to keep too much oil from accumulating in the head. So , what is your thinking on this. I would certainly appreciate your thoughts....and PleasE , feel free to Insult , call me a Dummy or whatever , as long as you give me your honest opinion.

Thanks so much in advance.

Ken

Wobbling cams make for more valve noise ... depending on the degree wobble. This also makes setting the valve lash accurately more precarious. What about the cylinder block deck? How much warp there? Another thing about severe overheating is ... the aluminum will stretch and experience localized softening. This sometimes shows up as a valve seat coming loose in the head and then separating from the head while the engine is running. Picture THAT carnage.

This was a learning exercise because simply junking the head in favor of a good used one would have been a FAR more reliable repair.

--

   ~Philip.

I'm hoping I won't get any wobble , since I only took material from the top of the cap it's not too wide ...just too tall and the and the pressure from the valve springs , I'm hoping , will keep the cam running against the top. Also , the two center journals were not honed so these two will help stop any cam wobble (I hope )

I checked the deck of the block and it's straight. This is a cast iron block .

experience localized

Personally , I have never seen this happen , but , that could make a mess , for sure.

You're right , it is a learning exercise and I know that a rebuilt or even a used head would be more a more reliable repair. Not a real bad job to replace the head if it doesn't work.

Have you ever been working on an engine and wonder just how much you can get by with , but were afraid to try it ? That was the case here. I remember as a kid seeing my Dad patch up some of those old engines with some things that were almost unbelievable , but they worked. I really don't know how long though . :-)

Thanks for your response . I appreciate it.

Naw, he just *says* he's a Toyota tech. In all reality, he don't know Jack! Right, MDT? ;)

No, I'm fibbing. I've picked his brain a few times now and he's always pointed me to the right direction.

Hmmm. That's interesting.

A close personal friend of mine was a mechanic for a Toyota dealer. He was apparently very good at it. When a transmission of mine (this is a long time ago) was overfilled, it didn't want to upshift until the RPM were very high. It shifted quite harshly when it finally upshifted. Once the car, and consequently the transmission fluid, warmed up, it shifted normally.

From what he told me, it wouldn't upshift because there was too much pressure. High oil pressure is consistent with the oil being cold so his statement made sense to me. I consider myself open-minded though so please embellish your claim a bit more. How does the fluid foam when there's too much?

Points:

1) There are three kinds of pressure in an automatic transmission. (a)line pressure: Is similar to constant regulated oil pump pressure in your engine. This pressure will go much higher than normal set pressure when the transmission is shifted into Reverse.

(b)throttle valve pressure: This pressure varies up and down with the amount of throttle application. This pressure acts against springs on shift valves and on normal regulated line pressure so that shifts come later and become firmer with greater throttle settings.

(c)governor pressure: This pressure signal rises with transmission output shaft speed. This signal tells the transmission how fast the vehicle is traveling and thus prevents overspeed in lower gears. Rising speed = rising pressure signal.

** In many electronic transmissions, an ECU with pressure bleed solenoids or stepper motors have taken the place of items B and C.

What your mechanic said to you is true to the extent that higher oil pressures delay upshifts and do make the shifts firmer. But IF the line pressure regulator or the throttle pressure valve(s) are binding in their bores in the slightest way until the valve body expands enough to free them completely, then unusual shifting will occur.

Fluid can (does not have to) aerate when it has rotating parts immersed in it. How much over full for this to occur would depend on speed of the rotating parts and the volume of the transmission case. In any case, the oil pump intakes fluid from the very lowest point in the oil pan .... not off the top surface.

--

   ~Philip.

Once again, good information, Philip. Thanks.

Thanks for elaborating on this . When I responded to the post I was merely addressing what Viperkiller said about overfilling with fluid creating more pressure , not the effects of high pressure , and how pressure is regulated. You answered it better than I could. Thanks KD