I'm about to renew the TX fluid on my 1990 LS.
(1) LexLS says to drain from the front cooler pipe, refill and repeat until clean. Would it not be quicker to drain the pan too, therefore replacing more fluid in one go? I intend to remove the pan anyway for inspection and to clean the filter. Which leads me onto my next question...
(2) Is it OK to apply a bead of red Hermetite to the (new) sump gasket? Is this stuff non-acidic? Alternatively, what sealant is recommended (and easily available in the UK) for autobox sumps?
Thanks in advance...

Yes you should drain/refill the pan first. So that old and new fluid don't get mixed.

thinking of doing this myself cleverdick , are you going to replace trans filter ? where did you get it + how much .and what fluid you do you intend to use .
as lexus fluid is crazy price ,I was going to use a good name dexron 3.
spoke to John lugo, trans specialists in manchester and they said all this about only using particular fluids was a load of B$%^&S . and as long as good qaulity fluid and regular changes were done everything should be OK . ?

i booked mine in for this next month

£50.. is that a good price??

Hi,
I've been reliably informed (and confirmed by the LexLS webmaster) that the filter is just a metal gauze which can be cleaned, so that is what I intend to do.
Concerning the fluid, I cannot stress strongly enough to ONLY use Toyota T-IV (which has superseded T-II). This comes up time and again on the forums - people have had horrendous problems as a result of using Dexron or Mercon fluids in the LS400 box. This transmission is very complex and delicate, and you could possibly write off the box by using the wrong fluid in it. It's not tolerant like an old Ford C3. Why take the risk?

Cheers Colin, but could you elaborate a little? After draining and refilling the sump, do you then remove the front cooler pipe and drain from there, or does it amount to the same thing? Which part(s) of the process do you repeat?
And what about the sump gasket sealant?
Sorry if I'm being pedantic, but I really would like to be 100% clear on this before I go ahead.
Thanks again,
Rich

yes although probably just a drain/refill rather than a complete flush? To replace all would cost more than that just for the fluid.

The fluid is drawn from the pan, through the internals of the transmission, through the external cooler and then back into the pan.

You want to do the pan first so that all fluid drawn up is fresh and because you disconnect the cooler line you stop any of the old fluid that was in the transmission from going back in and mixing with the new.

So yes after you do the drain/refill you disconnect the cooler, start the engine and let a litre out, stop the engine, put a fresh litre of fluid in through the dipstick tube and repeat untill the fluid coming out of the disconnected pipe is nice and clean.

Then check the fluid level is within the cold markings as a guide and then drive for at least 15 minutes and then check the level is within the hot marking. You shouldn't rely just on the cold markings as they are just a guide, the hot marking are the accurate ones.

To check the fluid level make sure the engine is running and move the gear selector through each position (pausing a couple of seconds between shifts) until back in Park and then check the dipstick (keeping the engine running).


Sorry I'm not sure about the gasket/sealant for the pan, may be worth searching through the forums on the US LOC site - many more LS, GS and SC owners in the US

Thanks Colin,
That's crystal clear now.
All I have to do now is to find some T-IV at an affordable price. Surprisingly, my local independent Lexus workshop suggested I buy some of their 'T-IV grade Dexron'! Now, even though I'm no expert, either it's the genuine stuff or it's not, and I hope you agree that I should hold out for the real thing at any cost!
Regards,
Rich

I changed mine a few months ago (just the pan) about 3 litre.If what you got in there seems clean just do that.I also changed the filter which is more like a screen than a filter, yes you could just clean it then spend the money on the correct Toyota fluid.

If you go to Toyota not Lexus you should get it cheaper £25.00 in my case,there is a big margin so haggle.

Dont forget to clean the magnets in the sump.

It appears that Lexus in UK do not do a gasket but will offer a tube of sealent which works fine.

jaggraveyard do the gasket in the USA

Hope this helps.