-always check trans fluid with car running
first post - i’ve been lurking for some time now, but finally decided to make an account. sup guys!

i have a 98 LS400 - 210,000mi and a cam seal went on me. driver side bad, passenger starting to go
the engine also simultaneously developed a knock when warm (i’m thinking from the lack of oil pressure) at one point it was “pissing” oil straight onto the exhaust manifold.
Love the car, got it in August 2020 right before the market blew up. so i decide to keep it and replace the motor, hearing about the difficulty replacing cam seals on the VVTi engines, plus the knock

turns out it was much easier to arrange for a JDM engine to be shipped to my house. the USDM Lexus version proved to be hard to find and the miles were much higher.

With some knowledge of motor pulls and basic repairs, i went full on go mode to get the daily back. There isnt much info i can find, so
Here is a little info on what you need to swap over! (pictures to follow once i figure out how)

-First thing was removing the JDM wiring harness; cant use it as it enters the firewall through the “left” or driver’s side

- i went ahead and drained the fluids. oil & coolant. both were surprisingly fresh. the timing belt was marked to have been done recently on my JDM motor, so i opted to not change it. upon visual inspection it was indeed brand new

-my coil packs were different, the plug-in shape specifically, so i swapped them over (along with my recently changed spark plugs)

- the fan bracket needs to be swapped. JDM has only a belt driven pulley with holes. USDM uses a studded pulley that the fan bolts to with a sheath type cover sandwiched in for the belt to ride on

JDM top - USDM bottom


-the JDM thermostat housing was lacking the small coolant line on the bottom, so i planned to use my USDM front/rear thermostat housing

- the rear coolant passage needs to be swapped also, as the fittings are on opposite sides and the lines will not match in the chassis for the heater core

- exhaust manifold flanges are different. i’m not sure if the catalytic convertors can just be 180°’d here, but the flanges on the JDM motor were not in the same orientation as my USDM. so those got swapped over

JDM cast manifold top - USDM bottom flange different orientations!

- dont think it’s necessary, but since i had mine cleaned i used the USDM intake assembly, upper and lower half with fresh gaskets. this made it easier when reinstalling vacuum lines - nothing new to bolt up or swap just replace what you took off



- motor mounts need to be USDM - or at least the bracket!! the JDM Celsior motor mount brackets have a slight angle to them. so the position would be offset to the rear and it would most definitely foul the firewall. new motor mounts anyways

torque everything to spec. it is not that hard and will save you headache/questions should you run into any issues.

my ONLY issue after the swap is now my transmission is acting up -when i come to a stop, go to take off in D or R, or let off the gas when coasting at any speed, the transmission comes out of gear on its own (like into NEUTRAL) and will then go back to drive gear when any throttle is applied at all even the slightest bit. If i come to a stop it will sometimes go in and out a few times before resting back in gear.
again if i apply throttle it stays/goes back into gear.

- i used Toyota T-IV
- i torqued the convertor correctly and followed spec when installing
- trans works PERFECT when cruising/downshifting to accelerate and all gears can be selected manually

issue SOLVED - forgot the basics of high school auto mechanics class - ALWAYS check trans fluid with the car running.
I was afraid to overfill, but was checking while car off and warmed up. it was too high, so i drained some out.
justtt checked while running after suggested here….it was just barely touching the dipstick. put my last quart in, got it up to the photo and its already better. Going to park it till the rest of the fluid i need gets delivered 👍

still need more but im sure this was this issue

Hopefully this helps someone who wants to use the JDM vvti motor, and maybe someone can help with my transmission! thx @LeX2K

 

Maybe dumb question but are you sure the fluid level is correct? Any CEL? What happens if you manually put the gear selector is a lower gear will the trans still go into neutral on throttle lift?

 

pretty sure, i will check again tomorrow. i drove about 20 miles so far to make sure it was all cycled through and a true reading on the dipstick. i think it was at the “o” on HOT
no CEL but i’ll run a scanner.
and i tested this, it holds gear strong no issues except when stopped it will still pop out

 

i was checking while car was off and warm. rookie mistake, thanks for checking me. pretty sure this is fixed

 

Oops. Correct way is check with engine running after driving for at least 15 minutes the fluid needs to be hot. Glad it was only a silly mistake.

 

thanks for sharing your thoughts here and the intricacies of a JDM motor compared to ours stateside. i've had my fair share of JDM motor equivalent swaps and yes you generally just swap the long block and reuse all the US-spec stuff.

glad you have the trans sorted! good call on LeX2K, as even i didn't know the car needed to be running when checking the ATF once at operating temps! something new!

 

glad to, i have been so grateful for forums and threads with this car so im hoping to help others. this swap was a fairly fun and easy weekend job granted you have a complete USDM motor.
well there ya go im not alone haha!

 

i usually just swap in the same amount of ATF that was drained, so i never needed to know you check the levels with the car running. i assumed no ATF leaks which is not realistic.
that means my LS was probably low on fluid as well with that lack of knowledge...doh!