ISGT35R

Hi guys,
I recently changed my ISF tranny fluid and installed headers on the vehicle at the same time. It seems the tranny fluid is leaking from the housing I think. Once the fluid leak happens it drops on the headers when I do +110mph and causes allot of white smoke to come out of the engine compartment. Now the mechanic believes he might have overfilled the tranny and there is some excessive fluid coming out of the tranny breather? I told him just to fill the tranny until the oil reached the filler hole level. Could he be true that the tranny is overfilled? We did remove the tranny during header installation and the tranny was perfectly leak free. Any idea how many Litres do the ISF tranny take? I had to drain the fluid when I changed my tranny oil cooler hoses since they looked in a bad condition. I used Lexus WS oil by the way and did the normal IS procedure which was filling the tranny to the top, crank engine, put tranny on Drive for a while then Neutral then Reverse a couple of times so the fluid circulates in the system.

What do you guys think I should do to fix this? ISF tranny fluid amount?

JKweezy

sorry but i've read the owner's manual and it says that the tranny is a sealed unit and will never need a tranny flush... i don't know how there is hole to fill if it's a sealed unit...

thainsane

I have heard the same thing too. I don't think you don't ever have to do a tranny flush but the interval is longer then other vehicles. Also I think it prevents people from doing it themselfs which then the stealership goes and charges you a million dollars to do it.

ISGT35R

well i can take pics tomorrow and show you the drain and filler bolt on the ISF tranny! both use crush aluminum washers too for sealant! wouldnt the tranny loose fluid when someone replaces the tranny cooler hoses? then you need to fill the tranny up to compensate the lost fluid during hose installation? i did read on here about the F tranny being sealed, but in fact when removed the tranny cooler hoses the tranny lost fluid and we had to drain it all and fill here up with new fluid. went to the dealer and they took VIN number and said WS oil is what i need (same tranny fluid used in the LS460L).

digger08

iTrader: (1)

Yes - there is a breather/ vent tube - if the AT is over filled it will vent out of this tube due to excessive fluid pressure.

There is no cooler lines as our cars run coolant back to the AT and not vice versa.

There is a fill plug on the side of the transmission and also a drain plug on the bottom of the transmission.


This is known as an overflow transmission.

Checking the level or draining overfilled AT fluid

I gets a little complicated from here, but basically you idle the engine until you have reached the optimum temperature
Min 95 degrees
Max 108 degrees

Then using a Techstream/ Toyota scan tool or putting the car into a self diagnostic mode it will tell you when the temperature is reached. This is built into the shifter and display (using a cheat code to activate.... (up/down/Shift Park....etc)

While the car is still running remove the drain plug on the bottom of the AT pan and wait for the AT fluid to run off or trickle out slowly. Seal it back up and you are done.

Obviously there is way more steps to this - but it just gives you an idea.

The pan holds 3.7 L, Torque convertor 6.7L and valve body hold 4.7L - you can service this in small increments through the pan only, but will take several drains and it will be come a dilution service at best.

So can it be serviced...yes. Is it a thorough proper service...No.

WS fluid is considered "Fill for Life" fluid, but I would suspect track use and extreme heat would shorten this to a serviceable interval of about 100K.

ISGT35R

digger08 thanks for your reply! i am not 100% sure of your explaination and seems like a new procedure of tranny service to me. i dont have a techstream either for my ISF.

can you confirm what am going to do is right?

1- lift the car up on stands, fill the tranny fully from the refill side hole
2- let the engine idle till working temp is reached (maybe 5-10 mins)
3- open up the drain plug and let the fluid out completely until it trickles
4- close the drain plug

thats it? wouldnt draining the oil leave the tranny out of tranny fluid? on my honda i have two plugs on the tranny. one drain plug at the bottom and one filler plug at the top which should be filled to the hole level until it trickles and that was it! why does it seem am understanding it the other way around here in the ISF? so i fill here up then drain here? if thats true then the oil is picked up and filled in THAT sealed system poeple talk about and the left over unwanted fluid is left underneath in the tranny overfilled case/pan?

i thought that tranny pan must have oil in there so the tranny can pick from?

i'll take pics today and post them on here to illustrate the plugs locations

ISGT35R

am confused i have a tranny cooler stock connecting to my 8spd F tranny on the right side of the vehicle tranny. i replaced the 10 piece hoses on there. are you refering to an IS350 by any chance cause am confused?


Edit: i can see 3 plugs on my tranny (refill/drain/overflow pug). the overflow plug has the word "CHECK" engraved on the plug

digger08

iTrader: (1)

The AT is fluid temperature sensitive.... and the reason the plug is not flush on the bottom of the pan and is the reason I gave youthe Min/Max temperature ranges - this transmission and most Lexus models use overflow transmission technology now a days- Not at all like a Honda - do not try to make a comparison.
You do not have any AT cooler lines that contain ATF and are external ....to access and perform a (what is considered) normal AT fluid transfusion.

Yes our car is the very same technique that is used on all 2006 and Up IS series - just different capacities - the design is all very similar with fill plugs and drain plugs.

I would not be attempting even a fluid level check, if you are not comprehending this AT deisgn or have access to the exact fluid temperature.

Tell your mechanic to check on Alldata or Mitchell databases for the exact process's on this Transmission type. It will contain about 5 pages on just checking the fluid level.

If you can fill it from the AT cooler - its news to me and you are on your own on this one.

lobuxracer

iTrader: (2)

Yes you do have lines with ATF in them running to the radiator and to a separate air/oil cooler. The other 2IS have coolant running to a water/oil heat exchanger on the side of the gearbox. Not the F.



Everything else you say is accurate. The level setting procedure is ridiculously complex for something that should be really simple. The good news is, as hot as it has been in some parts, you won't need to start the engine at all to get the right temperature.

digger08

iTrader: (1)

Thanks for the clarity.

After some more careful reading.... the self diagnostic mode for AT temperature works in conjuction with the Techstream scan tool. Not as a separate entity.

Does it say anything about an AT thermostat control within these lines?

lobuxracer

iTrader: (2)

No thermostat, but that's why they use both oil/water and oil/air for the gearbox. The oil/water stabilizes the temperature (hotter if it needs it or cooler if it needs it compared to the cooling system). This is much the same as our engine oil/water cooler. It warms the oil when it's cold, and cools the oil when the oil temp exceeds the coolant temp. It should (in theory) make cold cycle shorter.

As long as you can keep the cooling system temperatures stable, life is very good with these systems. Adding a bigger transmission cooler for street duty probably isn't the best idea without some kind of thermal shunt for the oil/air portion. ATF does need to be warm to work efficiently.

ISGT35R

here are some pics:

refill plug i used to refill with fluid


drain plug i used to drain fluid


and the overflow plug that i didnt use honestly yet, but will do really soon. the word "CHECK" is engraved on it, so am sure its the overflow plug


the shop am dealing with doesnt have a techstream nor any manual for this car, so thats why i came to the forums asking for help.

am thinking in common sense right now, since the tranny breather was spurting fluid out of the breather then all i need to do is start engine reach tranny to working temp then open up the overflow plug and close once fluid trickles?

ISGT35R

is this a typo? or you mean the overflow plug? there are 3 plugs i see on my tranny. refill, drain and overflow plug. please confirm

ISGT35R

is that the cheat code? can you elaborate on it since am not sure if the up down is from the stick or the paddle shift? i understand i need the techstream in conjunction as you mentioned earlier, but am considering using my universal scanner which is CAN compatible and check if i can monitor tranny temps...thats possible right?

ISGT35R

ok you answered my question if they had to work in conjunction!