4T80 torque convertor

[Daniel Evans]

long story short,

TCC solenoid replaced under warranty 89k.

failed again because of the oil seal at 129k

replace trans and convertor

convertor started slipping at 205k, shop is telling me this is common with this style of convertor.

I only drove it 3 miles when it started slipping, no service lights, drove to the shop 6 miles and had no issues.

How are these convertors different? and why did it go out so quick?

being tore apart now to inspect for trans damage, what are the odds? and what would you do?

[KHE]

If this is a 2003 SLS, I think they went back to the lock-up converter vs. the viscous coupled torque converter but I could be wrong. The viscous type lock-up had a silicone fluid in the lock-up circuit/clutches that would allow the torque converter to slip slightly (up to 200 RPM) so the driver could not tell when the torque converter locked up. This was done for the ultimate in smoothness that would be expected from a luxury car. If the seals in the lock-up circuit were worn, transmission fluid would contaminate the viscous fluid and the torque converter would slip and generate a LOT of heat which would eventually destroy the clutches in the torque converter.

I'm not sure why your replacement converter failed at 79,000 miles. How do you know it was slipping if there service engine light and codes were not set?

I had the issue with my wife's '97 STS a year ago. The P0741 code was setting intermittently for 6 years and we just kept driving the car. The intermittent P0741 code eventually turned constant and the trans began to whine when cold. Debris from the torque converter was plugging the scavenger screens. I had a decision to make for a 187,000 mile car... It was a southern car with no rust and my wife still liked the car so I installed a used transmission out of a '98 Concours myself for $350.00. If I would have caught it before the torque converter began generating debris, the local transmission shop (with an excellent reputation) could have fixed it for $1200.00. Once the converter began generating debris, the transmission was junk and the bill became much higher - approaching 2/3 the value of the car. That's why I found a low mileage used unit.

You need to evaluate the car at 205,000 miles - do you still like it? Is it rust free and in good shape? What could you purchase for the repair cost? What other repairs does it need? Take the repair cost plus the saleable value of the car as-is and what could you purchase?

[Daniel Evans]

thanks for the info. i had no codes, (yet) but when i accelerated I could tell i was losing power. the shift points were erratic at best.

at first i thought it was a vacuum leak but by feathering the accelerator i could get the car up to speed.

After letting the car sit i drove it to the trans shop that did the replacement with no problems and they told me the convertor was slipping.

they are inspecting the transmission now to see if further damage occurred.

I asked the same question why a convertor with 78k would go bad and he said they see it all the time on this style of convertor.

[rockfangd]

It is a common issue with these but thats low miles.

I have seen 100k ones have it.

my deville had 200k before it went. It warned me for about 1 year and still shifted perfect.

I am so used to the feeling I can always tell when the torque convertor is locked up or unlocked.

Do you do alot of stop and go? I am wondering if you have excessive lockup and releasing that it causes more wear on it.