neanderthl

Hey guys I have had my 92 sc400 for a little while now, and now I am having a drivetrain issue. It started as trouble getting the tranny to downshift when I stepped on the throttle. Sometimes it would happen and other times no. As the problem got worse, it would eventually never shift down after it had upshifted from accelerating from a stop. I couldn't even get it to change to a lower gear even if i slid the gearshift to a lower gear manually.

Finally, on a road trip, the car started to slow. When I got on the throttle, it behaved as if it were in neutral. The engine would rev, but no power to the wheels. So that is the story now. I can start the car, put it in gear, and nothing. Sometimes the car will lean forward a little, like it is trying to move (or move a tiny bit backwards, if it is in reverse), and make a little sound from the tranny. Sort of like something is partially engaged, or trying to engage.

I have good experience with manual trans, but i've never messed with an automatic

I am some experience with auto mechanics, but I'm no expert

Any advice would be greatly appreciated

neanderthl

I have done basic mechanics on average cars, a ton of work on my rx-7 (but the rotary engine is a totally different story), and built my electric car. Unfortunately, this gives me no experience with automatic tranny or torque converters or anything that makes them work.
So your guys' experience will be greatly appreciated

neanderthl

bump Anyone have any ideas to help me out?

lemmiewink

I would check fluid, and torque converter. I'm no expert either, but from what I have read. Automatics upshift and downshift using transmission fluid and electric solenoids. I would change/check fluid before doin electrical troubleshooting though.

The torque converter also uses fluid to transfer rotating mechanical motion from your engine to your transmission. If there is little fluid to transfer the motion, it feels like a clutch is slipping in a manual transmisson.

Also there might just be something wrong with the insides of your torque converter physically.

Change/check the fluid would be the first thing I would do.

This is all speculation though, and no first hand experience.

neanderthl

Thanks Ok so I had the tranny fluid flushed and replaced a couple of weeks before the car quit. I checked the fluid level, and the level is good, the color is good, and no metallic stuff in it, but Ive yet to drain the fluid to check for metal. Is that the next step?
does the desription of my prob sound like a destroyed torque converter?

Also the idea of an electric solenoid failing seems possible What sort of electric parts failing could cause this?

neanderthl

Any ideas? Should I just yank the motor and have a look? Is it better to drain the fluid first to look for metal? are their any obvious sensors or solenoids to check before pulling everything apart?

CLRH2O

What ever happened for you with this situation? I've recently had the same problem. I tried swapping in a brand new Torque Converter - which fixed nothing. Next I'm wondering if it's the shift Solenoids... but am leery to think that since it's ALL GEARS in ALL POSITIONS. So how could every single one of my shift solenoids have died all at once. it seems like that would have been impossible.

SChema

iTrader: (2)

Automatics can be a pain when things go wrong. The shifting mechanism includes the solenoids and the valve body with a series of check valves and spool valves that relies on transmission fluid pressure to shift into gears. Contained inside are a series of bands and clutch packs that engage certain gears. It sounds like your transmission is slipping quite badly, which will require a complete overhaul or you could find a used one to replace it with.

Checking the fluid is a good start though, at least that will rule out one of the cheaper solutions. Make sure you put the proper fluid type in as well, the wrong type could also cause these symptoms.

CLRH2O

Rotor - if you can drop by my thread and check out what's happened, what's been done so far and where I'm at now asking for more info please do.

Couple of quickie answers/points though. I only use Toyota Type-IV trans fluid. And the car now has a brand new Torque Converter in it but the problems still persist.

Worst part though about this is all happened instantly and on a two oner 153k miles trans. It's been babied as well. Every single gear forward and reverse just went out in one day. From solid to blam nothing in a 24 hour period. My car also still has NO CELS so it's reporting everything as being hunky dorey! Check everything here:

https://www.clublexus.com/forums/per...antly-die.html

If this is your field I'd GREATLY like some input if you have the time

CLRH2O

The thing that's gutting me right now is I'm currently unemployed (ugh) and a rebuild is averaging $1400 to $1600+ EVERYWHERE I've called so I'm trying to expend ALL possibilities before going into even more Credt Card debt.