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Discussion Starter #1
I need to replace my transmission in an 07 Sienna. Trans fluid line blew off the radiator and I noticed the coolant had been leeching into transmission possibly leadin up to that as the radiator was breaking down. A couple days of use after I fixed the radiator and refilled fluids, the transmission started shifting funny, so now its only a matter of time before it self destructs.
- Can I yank the transmission without dropping the whole engine.
- Is it easier to remove it if the motor comes out with it.
- Is that torque converter at risk of coolant damage.
Thanks in advance for any input. All I know right now that isn’t self-evident is that the black bolt goes back in first. Thats it.
 

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2015 Sienna / 2018 RAV4
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Someone else did a home tranny swap. IIRC, they were able to drop it out the bottom with the engine in place.

I needed a rear main seal done on my '08 years back, and they did it with just dropping the transmission also.

Before you go to this extreme, why not try a shop with a flush machine. Tell them the situation and have then double up on the BG tranny solvents (or whatever system your shop uses). I'd also recommend dropping the pan and changing out that filter (YES, there really IS a block of Dacron filter inside that metal housing, and it can get pretty clogged up). You might be able to save it.
 

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Pull the dipstick and see if you got “strawberry milkshake”, if the ATF is that clean when it mixed with coolant. Or chocolate latte if the fluid is dirtier.

If coolant got into the transmission yeah it’s a goner. The converter needs to be replaced as well.

You can try a last ditch effort by a full flush of the fluid and see how much time it might buy you.

To pull you support the engine from top and drop the subframe. There might be YouTube videos on that.

Check the local Transtar or WIT parts warehouse if you have one near by. Or check with local ATRA shop if you plan to farm out the work. Check references.

 

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Discussion Starter #4
Thanks for the responses. I had gotten an opinion from my local transmission shop. They said that the clutch plates get irreversibly impregnated with the coolant, so while flushing can buy you time in less extreme situations, it still won’t save it long term.

Also I’m not the type to wait and wonder when I’ll get stranded in the middle of nowhere in a minivan.

So the question now is transmission type, a quick look online lists the U151E (fwd) as being used in v6 solaras, siennas, rav4s, avalons, highlanders, and the lexus rx and es, through a year range of 2004 to as late as 2013 in the highlander.

Are there significant differences in each vehicle application? Or can I pull a transmission from any of the above vehicles for use in the 07 Sienna.
 

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2015 Sienna / 2018 RAV4
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For 2007, Toyota switched from the heavy weight T-IV fluid to the lightweight WS. From what we've been able to tell, there is zero or very limited hardware differences between U151E or F autoboxes pre or post the fluid change. Reportedly the clamping rates of clutch packs was recalibrated via TCU software instead without changing clutch material or the valve body solenoids. But... ask questions.

So this can get a little dicey.... Could you just plug in a T-IV (2006) box to your WS programmed TCU? I'd get the fluid flushed out first. I've also read that any change requires 'pairing' of the TCU to the box. This is mentioned in some 6 speed and new 8 speed documentation, but I'm not sure if it applies to the 5 speed.
 

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Discussion Starter #6
If thats the case, sounds possible to carry over tcm from the donor vehicle, or get a junkyard tcm match to trans donor vehicle. I wonder if it would conflict with ecm though. If the only programming differences are in the data output to the trans, then it would work. If the tcm has to talk to the ecm for things like briefly defueling to lower torque during heavy shifting then there could be problemos.
 
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