Replace valve body on A541?

Four years ago I bought a '95 Lexus ES300 that shifted very smoothly but had dark brown transmission fluid. I had the transmission
power-flushed on a T-Tech machine and immediately thereafter the shifts became harsh and slightly erratic. Somebody suggested that dirt dislodged by the flush had probably clogged/damaged the valve body.
Over the next 4 years I drained and filled the transmission a number of times, and each time shifts would get smoother for a few days. Last month I finally had it power flushed again, and this time there was a significant but temporary improvement.
Does this sound like a valve body problem? If so, how hard is it to replace (with a remanufactured unit)? Is this something that can be done in a few hours by a non-professional without specialized tools?
Thanks, Tripurari
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It could be your valve body, but it could be other things too such as a bad accumulator, etc. I would check your throttle pressure cable first along with a line presure test on the trans to see what is happening to the pressure during the stall tests and normal shifting. If it is out of spec, then an adjustment or replacement of the throttle presure cable could bring it back in line. You can easily do this yourself by buying a pressure gauge kit off Ebay for $35 (Page Autosupply).
As to replacing the valve body: Yes you can do it yourself, but you need to be mechanically experienced and meticulous because there are many parts and steps you need to go thru to get the valve body off and back on. It can be done, but it IS a challenge and will take you 6+ hrs the first time most likely. You will also need a ATSC trans manual for your transmission and need to spend several hours familiarizing yourself with the removal and installation procedures. As well, you need an accurate torque wrench that can do in-lbs. And of course, you should not mind having trans fluid all over you and your garage floor. :)
Unless you have balls and like a challenge, I would not recommend re-building the valve body yourself. I say this because I have done it and would not do it again. Why? There are all kinds of problems you can run into such as the trans service manual not being up to date on the latest changes, parts falling on the floor and getting damaged, stuck valve plugs, wrong re-assembly or messing parts up (and there are LOTS or parts!), stuck or bonded gaskets, etc. You can buy a reman'ed valve body from Phoenix hard parts for around $200 with a core return on your old one. They test it on a dedicated hydraulic VB tester to make sure it works properly. If you go that route, be sure to call them and ask them about the shift solenoids and whether they are also included. If not, I would recommend a new solenoid kit also from bulkparts online. While in there, you should also replace the o-rings and seal on the 3 large accumulators in case one of those has a blown ring.
cheers,
dave mc
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First of all,if there is sludge,dirt or any material at all that requires the trans to be flushed,you have much bigger problems than a valve body. The trans should never have a need to be flushed of material of any kind if your tranny is in good condition.It would have to be metal,clutch material,or a combination of both.When you change fluid and filter,thats pretty much how you get your first hint of what condition your trans is in.If there is lots of metal filings or clutch flakes or sludge(probably combination of both),then you are not far away from trans failure. davemac wrote:

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davemac wrote:

Thanks, Dave. The pressure cable seems to be fine, I'll try the pressure gauge kit. Is the pressure likely to be knocked off spec. by a power flush?

Are any of the parts hard to remove? Do the tubes come off easily? I have a Toyota factory manual but not the ATSC manual.

Heh!
Wouldn't dream of rebuilding the valve body myself.

Thanks a lot for all the information. Other than the valve body and the accumulators, is anything else likely to be damaged by a transmission flush that would result in harsh shifting?
Regards, Tripurari
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Nothing comes to mind except for a sticky pressure regulator or other valve in the valve body,a blown thru check ball possibly, some gummed up filters within the valve body itself, the throttle pressure solenoid (if it applies to your trans). A harsh shift can also be caused by a delayed shift for whatever reason. You can do a road test and determine if it is shifting late fairly easily based on the specified road test in the factory diagnostics. One thing you may want to do before diving into the valve body stuff is to check/replace your trans filter screen in case that is blocked up a bit. Just order a replacement pan gasket and filter from bulkparts and try that first. That will allow you to take a look at the valve body underside first and gauge the difficulty of that job.

No, the parts are not hard to remove. The tubes come off by gently prying with a large screwdriver, being careful not to bend them. Just take your time, segregate the removed parts, store them on a piece of aluminum foil that you can close up to keep them clean. The factory manual may be ok since I think most of the ATSC manual is based on it from what I recall.

Like I said, it could be a delayed shift for whatever reason such as a fluid leak at one of the many seals within the transmission. Go thru the trans diagnostics chart and flow chart in the factory service manual to see if you can narrow it down. There is always a chance the fault may not lie solely within the valve body. You take your chances. :)
good luck,
dave mc
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I recommend that you do not power flush the transmission any more unless it has been done routinely every 3 or 4 years since the transmission is new, otherwise, you will have the problems that you are experiencing. If the automatic transmission fluid is very black, then the most you should do is drain and re-fill.
AFAIK, there are no OEM remanufactured valve bodies, only remanufactured transmissions.
I doubt if replacing just the valve body would eliminate the harsh and erratic shifting because the stuff that was dislodged by the power flush could be stuck anywhere inside the transmission. My guess is that a new valve body would cost in the neighborhood of $1,800 so that is a pretty expensive part to replace without guaranteed success.
I would not attempt replacing a valve body without a factory repair manual. I suggest that you look at the procedure and then you will have an idea of whether it is something you want to tackle.
--

Ray O
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Ray O wrote:

Five years ago I got different advice from this board. Everybody advised against drain & refill because the detergents in the new ATF would dislodge dirt that could stick somewhere. Power flush was preferred as it was likely to flush away the dislodged dirt. Then there were some people who advised doing nothing.
Regards, Tripurari
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When in doubt, stick to the factory recommended services. A look at the maintenance schedule in your owner's manual probably lists just a drain and refill for your automatic transmission and does not list power flush anywhere.
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Ray O wrote:

Sound advice, except that the previous owner didn't do the needful. The manual doesn't say anything about recovering from brown/burnt ATF. In any case the old advice I got didn't work out so I'll try your suggestion on my next car.
Regards, Tripurari
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If the ATF is brown or burnt, then the best thing to do is just a drain and refill, which happens to coincide with the factory recommendations. I took a look at the procedure for replacing the valve body, and it does not look that difficult, although you should plan on spending quite a bit of time on the task. Good luck!
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snipped-for-privacy@cnds.jhu.edu wrote:

are you using the correct fluid? some cars are picky. i know hondas are. are toyotas?
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mike wrote:

I use the specified Dexron III, though not the expensive Lexus brand. I use Mobil 1 synthetic ATF.
Thanks, Tripurari
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That's why I'd always change the strainer and wipe the pan of all the metal shavings that would otherwise circulate with the flush with a Fram ATF kit, for about $20 every 24-30K miles.
snipped-for-privacy@cnds.jhu.edu wrote:

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snipped-for-privacy@hotmail.com wrote:

I have done this once, though after the first power flush. As always it made the shifts smoother for a few days.
Regards, Tripurari
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I am among those who do not like the idea of a power flush. IMO periodic replacement of the strainer atf fluid and wiping clean the pan is the best maintenance for the tranny aside from not horsing a tranny known for sluggish line pressure that cause soft shifts and accelerated clutch/brake band wear.
If spraying compressed air can't rid the metal shavings from the pan, why do dealers suggest their flush machine can get them out of the system and from the magnets?
Like others said, the power flush probably got some shavings/particles somewhere they don't belong. The most likely places are the valve body pistons and shift solenods, but we can only provide a guess here.
Replacement with a rebuilt valve body will work only if you dont' have other problems with the tranny. But a main line pressure test may be able to tell you a few things.
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snipped-for-privacy@hotmail.com wrote:

===============Any metal particles in the pan should be trapped and held by the permanent magnets
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(The magnetic particles are iron/steel and indicate gear wear; the non-magnetic are copper based and indicate bushing wear.)
Yeah, the machine won't wipe the magnets or the pan is the problem. And magnets are less effective when already coated. BTW it would be interesting to drop the pan and see what's left in the pan especially after the first flush.
IMO, dropping the pan, changing (not cleaning) the strainer, and wiping the pan and magnets is the proper way to clean off these magnetic and non-magnetic particles. "Flushing" is more appropriately called "fluid exchange", and is more economically accomplished with regular drain and refill.
Daniel wrote:

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