New Lumina owner - tranny leak

[rubenyc]

Hey guys,

 

My name is Ruben, I'm from Holland. I've been reading this forum for the past week and a half since I bought a '91 Lumina sedan with the 3.1. Got it from the first owner, who basically only used it in funeral processions since new (almost anything American will work for those here). It has approx. 75,000 miles, looks neat and feels like new.

 

The thing is, when I bought the car it had been stored (indoors) for over 2 years because they had bought newer Luminas for their business. When inspecting it I did notice a small puddle of transmission fluid on the floor, but I didn't give it much thought, thinking a gasket might have dried out and it would stop leaking when it got some exercise again.

 

Now I've put about 150 miles on it and I'm still losing tranny fluid (I keep adding it). It also hangs on to first gear pretty long, and drops from 3rd to 4th very quickly with a sort of slight thump. This gets better as it warms up. Otherwise it shifts up and down smoothly. (BTW, I read that these '91s are supposed to have a 3-speed, but mine definitely has a 4-speed with OD...!)

 

It also stumbles for a second when accelerating from a standstill. I read in another topic that this might have something to do with the TPS (don't know what that is, to be honest).

 

Anyway, with all these things in mind, what do you guys think could be the problem with my tranny? The car is going into the shop next week for new fluid and a filter, I could let them diagnose it but it might help if I had some advance knowledge of it... ;-)

 

Thanks.

[TeeJay3800]

TPS stands for Throttle Position Sensor.

 

'91 Lumina 3.1's came with either the 3-speed for 4-speed transmissions.

 

Your leak is most likely caused by a bad pan gasket. The kit from GM comes with a new gasket, filter, etc. IIRC.

 

Also, every 3.1/4T60 car I've driven seems to hang on to first gear longer than what would seem necessary. I would recommend adding an adjustable vacuum modulator which helps you control shift feel, and on my car it helped the transmission upshift sooner at light throttle.

[rubenyc]

Crawling under the car today the pan did seem to be what's leaking. Tightened the bolts where possible, but of course that didn't solve much. It's going to the mechanic's on Wednesday (fluid/filter, and as it turns out, a gasket ) so I guess I'll leave the car alone till then since it really doesn't seem to hold on to its fluid very long...

 

I'll wait to see how it shifts when it's been freshened up, I'll keep your tip about the vacuum modulator in mind in case it still bothers me. Thanks!

[DaveFromColorado]

I would also recomend a full tune up too, spark plugs, spark plug wires, PCV valve, fuel filter, air filter, and an oil change.

 

--Dave.

[3pt1lumina]

I adjusted the vacuum modulator on my 90 Lumina (3.1/4T60) and it made a huge difference and now the car shifts normally.

[TeeJay3800]

A modulator can actually help the transmission shift BETTER than normal. It helped mine shift much quicker and firmer in normal driving, and WOT shifts are VERY fast and precise.

[THe_DeTAiL3R]

Yeah gasket is a common problem, but really only an issue if it's CORK. Just make sure it they put on some sort of rubber gasket, not cork, and you'll be fine.

[GP1138]

It could also possibly be the Transmission Axle Seals. If it seems to be coming from between the wheels and the transmission, that's your problem. I've done this myself, it's not too awful hard.

[rubenyc]

It's definitely the pan, when I add fluid I can see the drops. I'll make sure they put on a proper gasket. ;-)

 

The vacuum modulator sounds good. However, believe it or not, the car seems to shift better now than it did a few dozen miles ago. A friend of mine's Ford used to shift horribly, and it was solved by disconnecting the battery for a while, which apparently reprogrammed it. I figured maybe that's what's happening with my car, since it was stored with a flat battery before I bought it, and it will shift better as I drive it...?

 

Anyway, the sort of gradual thump when it shifts from 3rd to 4th is still there, but it's less fierce and at least it uses 3rd now. I'm hoping it will go away altogether as soon as the tranny's been serviced. I'm not using the car till then, it scares me now to drive it if I haven't added any fluid for the last hour...

 

Dave: thanks for the tip. I did change the engine oil and filter today, I'll get to the rest next week.

[Regal_GS_1989]

The vacuum modulator sounds good. However, believe it or not, the car seems to shift better now than it did a few dozen miles ago. A friend of mine's Ford used to shift horribly, and it was solved by disconnecting the battery for a while, which apparently reprogrammed it. I figured maybe that's what's happening with my car, since it was stored with a flat battery before I bought it, and it will shift better as I drive it...?

 

The battery going going dead, or being disconnected will have no effect on the way the transmission shifts. Your transmission is not electronicly controlled. The shift points are determined by a TV cable, and the firmness is controlled by the vaccum modulator. With an adjustable vaccuum modulator, you are able to control the firmness of the shifts by increasing or decreasing the ammount of vacuum. The more vaccum, the softer the shift, the less vaccuum, the firmer the shift.

[rubenyc]

The battery going going dead, or being disconnected will have no effect on the way the transmission shifts. Your transmission is not electronicly controlled. The shift points are determined by a TV cable, and the firmness is controlled by the vaccum modulator. With an adjustable vaccuum modulator, you are able to control the firmness of the shifts by increasing or decreasing the ammount of vacuum. The more vaccum, the softer the shift, the less vaccuum, the firmer the shift.

 

I know how general things work on my car, but this shows how knowledgable I really am when it comes to these things. :-P Thanks for the explanation.

 

I'll let you know what happens with the shifting after the car is serviced this Wednesday.

[White93z34]

i've seen situations where cars will sit for awhile and the trans will act weird for awhile, till they start to get used more.

[rubenyc]

Well had the work on the tranny done yesterday, new fluid, filter and pan gasket - black rubberish, not cork. It seems fine now, no more leaking (as far as I can tell at this point), shifts smooth.

 

The only thing I've noticed is that the torque converter whines sometimes, ever so slightly. It seems to do it only on left turns under moderate to heavy acceleration. The trans doesn't slip, or the car doesn't stumble or hesitate, it just makes the noise. Goes away when the revs drop/when the car shifts up. The fluid was at mid-level on the dipstick. I added a little bit, didn't seem to help it.

 

Anyone familiar with this? I mentioned it to my mechanic and he listened to the noise, says it's nothing to worry about...

[Crazy K]

it is probably caused by the fluid sloshing in the transmsion, which allows a little air the get sucked into the filter and throught the tranny. Some member like to run their transmission a little higher than the mark, by about 1/2 a quart. (about 1/2 a liter)

 

it helps prevent the problem.

[rubenyc]

Thanks Crazy K, I'll try running it with a little more fluid.