Torque Converter
#2
10-14-2012, 11:16 PM
If a tranny is slipping, you might still have one or two gears that's ok. You may also be able to get up to speed and cruise on the freeway ok and, when given light gas, you accelerate without a problem. While changing gears you'll also probably get a rattling or banging from the clutch packs and/or drums not grabbing very well. This causes vibration and shaking anytime the affected gear is changed. A bad transmission is most often noticed while changing gears... That's key.
A bad torque converter, on the other hand, will affect all gears. Like a persistent slipping that won't ever go away (but in reality the torque converter just isn't locking in). If you step on the brake while in drive and rev, you'll also notice the engine revs up a long ways before starting to stall... Then while driving, just keeping the car going is a chore and you'll have higher RPMs. Gear shifting will be normal, though. What really sucks is when you have a combination of the two, but that's pretty rare.
A bad torque converter, on the other hand, will affect all gears. Like a persistent slipping that won't ever go away (but in reality the torque converter just isn't locking in). If you step on the brake while in drive and rev, you'll also notice the engine revs up a long ways before starting to stall... Then while driving, just keeping the car going is a chore and you'll have higher RPMs. Gear shifting will be normal, though. What really sucks is when you have a combination of the two, but that's pretty rare.
#3
10-15-2012, 12:10 AM
So with my blazer...It starts fine, goes into gear, but never goes above 25 MPH but no faster and it doesn't appear to be shifting from gear to gear correctly...So would you think its the Transmission or the Torque Converter?
#4
10-15-2012, 12:39 AM
Before you do anything else, check your transmission fluid. Transmissions won't shift without fluid.
One you do that, you can continue below:
If it still won't shift from 1st into 2nd, then I would lean more toward the transmission. If you give it a lot of gas and it still won't shift, then probably the transmission.
Try the torque converter test to make sure, though. Put the car in drive, stomp firmly on the brake, and rev it lightly for a second or two and make sure the car doesn't move. If the car engine starts to stall at 1800 RPMs or below, you're torque converter is probably good. This test basically makes sure that the torque converter is responding to fluid pressure and beginning to lock up (as it should).
The good news is that not shifting gear can also be as simple as a dirty valve body, which controls shifting gears, so I wouldn't necessarily worry about a rebuild until you get it to shift (if that is indeed the problem).
One you do that, you can continue below:
If it still won't shift from 1st into 2nd, then I would lean more toward the transmission. If you give it a lot of gas and it still won't shift, then probably the transmission.
Try the torque converter test to make sure, though. Put the car in drive, stomp firmly on the brake, and rev it lightly for a second or two and make sure the car doesn't move. If the car engine starts to stall at 1800 RPMs or below, you're torque converter is probably good. This test basically makes sure that the torque converter is responding to fluid pressure and beginning to lock up (as it should).
The good news is that not shifting gear can also be as simple as a dirty valve body, which controls shifting gears, so I wouldn't necessarily worry about a rebuild until you get it to shift (if that is indeed the problem).
#6
10-15-2012, 01:24 AM
Exactly. Here's a simplistic way to think about it. A torque converter is a donut with a hole in it which spins around a shaft in the center. The torque converter is attached to the engine, and the shaft is attached to the transmission, which is then attached to the wheels. When the engine spins faster, the "donut" shrinks, locking onto the shaft of the transmission and starting to generate force to the wheels. There's always a little bit of friction on the shaft, which is why when you let off the brake the car moves forward slowly. Give it gas, and the torque converter locks onto the shaft and transmits most of its energy to the wheels.
So if you hold back the wheels and rev a little, the engine should bog down at say, 1800 RPMS or less. If it doesn't, something is wrong with the torque converter. Just don't do it too many times or for more than a second or two, because the heat and friction can damage the torque converter, not to mention the poor engine.
BUT CHECK THE TRANNY FLUID FIRST. Lol, it's so important.
So if you hold back the wheels and rev a little, the engine should bog down at say, 1800 RPMS or less. If it doesn't, something is wrong with the torque converter. Just don't do it too many times or for more than a second or two, because the heat and friction can damage the torque converter, not to mention the poor engine.
BUT CHECK THE TRANNY FLUID FIRST. Lol, it's so important.
#7
10-15-2012, 08:52 AM
So I started it up this morning...Put it in Drive, Revved the motor and it didn't appear to bog down in anyway, it even tried to pull a little...and I checked the transmission fluid first thing and it appears fine...So would you say it's the Torque Converter?
#8
10-15-2012, 09:31 AM
Could be, but a bad 1st gear gives some of the same symptoms as a torque converter and since it "pulled a little," I'm hesitant to say that's the problem. You said you can't go above 25mph. Does it not leave first gear?
#9
10-15-2012, 09:33 AM
On another note I COMPLETELY forgot to mention is that torque converters going bad can also just lock up. That's also possible. If you still can't leave 1st, I'm probably leaning toward the transmission.