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My 1999 LS400's transmission is ******ed. Any advice?
Hi,
I own a 1999 LS400 with ~118k miles on the clock. It sat for years before I got it, its a bit of a restoration project. Just the other day, I'm parking the car and I notice a trail and splatter of oil on the concrete.
So here's all I know:
The transmission fluid leaks, and fast. But it only leaks when the rear wheels are being driven.
The leak comes from the bell housing. There is a small hole which I assume is to allow trans fluid to exit and for a leak to be spotted.
The car did still drive, I got it the 25 miles home without issue (and I did check that I'd have enough fluid to make it).
When moving it in the driveway yesterday, It did seem to take longer to engage into drive/reverse. It didn't take off and coast like it usually would when taking the foot off the brakes.
My guess is that the torque converter is toast, but that is just my guess with what I've seen so far. As a 20 year old with no garage and limited hand tools, this seems like something out of my ability to repair. Any advice or ideas?
Help is much appreciated!
-EVAN Back in the day when it worked The fluid leaks from that hole between those bolts.
are you sure it's trans fluid and not engine oil? that hole is the access point for the torque converter and you have both the trans and block mating there. oil can come out of a failed rear main seal.
it might very well be fluid due to the long Park to Drive engagement. does it shift fine as well? i'm surprised at that low of a mileage the trans should still be fine. has anyone possibly overfilled it? what the fluid level now? check the trans dip stick.
I would first ensure that fluids are at the proper level, these trans can be picky if they don't have the right capacity. And you've confirmed its RED ATF fluid leaking correct?
Its not engine oil, I thought it might be but the red color to it said otherwise. The trans oil dipstick showed plenty when the leak started but now reads pretty low. Shifted fine when I drove it last.
It's odd that ATF leaks only when the rear wheels are driven. If you're losing ATF "fast", everything aft of the transmission should be real wet. You drove 25 miles with no operational issues so the unit is probably fine. Locate the leak and repair it. Pull the inspection cover and take a peek.
The slow engagement is most likely low fluid level due to the leak.
The transmission pan was soaked with the stuff. I'll try get the inspection cover off in a couple days (the black plate seen held in by those two bolts in my photo, right?)
The transmission pan was soaked with the stuff. I'll try get the inspection cover off in a couple days (the black plate seen held in by those two bolts in my photo, right?)
Yes. It's kind of hard to see anything once the cover is off but a mirror helps o see behind the converter.
The first step is locating the leak and not guess where it is. Sometimes a florescent dye is helpful. Pour it in, run it for a few minutes and use a black light to pinpoint the leak. The dye will glow yellow under UV light.
The images above is the same stuff. The left image is older packaging. You can get a UV LED pen light pretty cheap. This one came in an AC leak detection kit:
Hi guys, taking out the transmission and bringing it to a shop seems like my easiest way to deal with the issue.
I looked behind the cover and I can follow the trail of fluid under the flywheel and torque converter, but that's as far as I can see it before the bell housing curves up.
Any more thoughts or ideas before I begin the removal? The leak seems to be too far inside the transmission to find the source without removal.
Also do you think finding and fixing the leak sounds possible, with limited tools and no garage?
You're super sure? The engine isn't leaking oil from somewhere else that might be confusing you? Maybe the rear main seal idk.
I just say this because like, we want to be super confident about our diagnosis before we start pulling transmissions. I'd want to rule everything else out. You did confirm it's red transmission fluid that's leaking out? And not any other fluid type?
It's also super strange for this transmission to suddenly have a catastrophic oil leak. They're pretty bulletproof and this would be abnormal.
Pulling the transmission would allow you to examine both the transmission and the engine. You can probably have it out in a couple of hours. Put match marks on the drive shaft and flanges so that it goes back together in the same orientation.
The only problem is lube (engine oil or ATF) gets flung all over back there so it'll be hard to tell the origin of the leak.
Since the engine and trans are going to be separated, I would just replace the rear main seal on the engine, and replace the input shaft seal and pump gasket as a minimum. Input shaft seals can pop out of the pump; it's rare, but not zero. Inspect the pump bushing that the converter snout rides in.
Yeah I'm pretty sure. The fluid had a slight red hue, and it started leaking much faster when I topped off the fluid last week.
A mix of the car sitting for years and me regrettably beating on it a bit too hard one night should explain why a somewhat low mileage transmission is acting like this...
I've found a couple videos on Youtube on LS transmission removal and have a bit of skill in working on cars, so I'm not too worried about the work (but it would be the biggest job I've done).
I guess the only way to really find the leak is for the transmission to be taken apart (=$$$).
I'll look into getting the seals and gasket replaced as you said, thanks.
I don't have a clear understanding of transmission anatomy though, so I'll need to do a bit more research on the shaft and pump.
08-10-23, 05:05 AM
My 1999 LS400's transmission is ******ed. Any advice?
