Torque converter going out

[rremesal]

Team, 

 

2018 Silverado with the 5.3 and 8L90 transmission. 

 

About 5 days ago, I started getting the torque converter shudder. Based on descriptions that I've read before, in having the same symptoms... The rumble strips. Even my wife felt then. 

 

What options do I have to fix this?

 

Thanks, 

Ric

[Snowcamo]

Complete rebuild including a new tq converter.  That's the best option. 

[newdude]

38 minutes ago, rremesal said:

Team, 

 

2018 Silverado with the 5.3 and 8L90 transmission. 

 

About 5 days ago, I started getting the torque converter shudder. Based on descriptions that I've read before, in having the same symptoms... The rumble strips. Even my wife felt then. 

 

What options do I have to fix this?

 

Thanks, 

Ric

 

 

Change the fluid first.  GM p/n 19417577.  The dealers can do this as the "8 speed shudder flush" procedure in TSB 18-NA-355.

 

Here's the TSB - 18-NA-355 1..17

Edited October 23, 2025 by newdude

[newdude]

34 minutes ago, Snowcamo said:

Complete rebuild including a new tq converter.  That's the best option. 

 

 

Fluid.  Chances are its original in OP's truck.  

[Snowcamo]

8 minutes ago, newdude said:

 

 

Fluid.  Chances are its original in OP's truck.  

 

Guys your awesome. I'm all for fluid changes.

 

But please note multiple users from before the new body style rotating fluid changes remove the grit in the system. That grit keeps the trans going. After that's gone failure...

 

I totally understand gm and the failed attempt to temp resolve the shudder. It's just a crap built trans, let's face it. Is what it is. Since mine was rebuilt the truck is a whole different animal.  Completely.  The shudder is just symptoms of underlying issues like a oil pump housing being gouged and loosing pressure amongst other issues. 

 

Peace.

 

 

[rremesal]

At about 30K miles, I dropped the pan and changed the filter and refilled with fluid. I understand this is only 25-30% of the fluid, but it isn't all factory fill.

 

What sucks is that I don't really abuse this truck. I have a boat...4500lbs total and I have done a couple of long distance trips with the boat, but I don't abuse the tranny. I've only had the boat for two years. 

 

Anyway, I am tempted to do the flush, but I'm afraid I'll spend $800 only to end up doing a rebuild regardless.

 

Tough choices ahead...

[rav3]

I'm curious, how many miles on it? Has it ever had fluid changed & thermostat bypass installed?

[rremesal]

113k miles

Pans dropped, filter changed and fluid refilled

I have not messed with the thermostat. However, the trans doesn't go above 185 or so under normal use. I don't tow much

[rav3]

Since it's an 8 speed, there was a Service bulletin that recommended changing the fluid to a better Mobile 1 ATF. Was this ever done?

[rremesal]

The TSB was never done... Never had this issue until now.

[rav3]

If it were me (and it's not) I'd do a complete flush adding the new recommend fluid. I don't think it would be good to mix it as in a drain & fill. That only gets about half of fluid. My thoughts.

[rremesal]

I'm of the same thought as snowcamo... The flush is an $800 bandaid for something that's going to go anyway. 

There is also the lifter situation hanging over my head... Another ticking time bomb. I've had the system off since shortly after I bought the truck new, but I don't know much longer that's going to hold. 

 

Seriously considering dumping this truck. I just put 4 new tires 3 weeks ago and the truck looks pretty mint for being 7 years old. 

 

Such is life.

[silveradosid]

pop out the fill plug and take a long qtip and swab the bottom of the pan, if it is covered in black crap pretty well tells you what you are going to have to do

[Snowcamo]

5 hours ago, rremesal said:

I'm of the same thought as snowcamo... The flush is an $800 bandaid for something that's going to go anyway. 

There is also the lifter situation hanging over my head... Another ticking time bomb. I've had the system off since shortly after I bought the truck new, but I don't know much longer that's going to hold. 

 

Seriously considering dumping this truck. I just put 4 new tires 3 weeks ago and the truck looks pretty mint for being 7 years old. 

 

Such is life.

Don't dump it. Wait, it gets better. The main reason I run GM is aftermarket parts support. These trucks are built to be rebuilt lol. Seriously once you start putting aftermarket parts on the truck really wakes up. 

 

I guess it really depends on if you plan to keep the truck or not.  

[newdude]

18 hours ago, rremesal said:

At about 30K miles, I dropped the pan and changed the filter and refilled with fluid. I understand this is only 25-30% of the fluid, but it isn't all factory fill.

 

What sucks is that I don't really abuse this truck. I have a boat...4500lbs total and I have done a couple of long distance trips with the boat, but I don't abuse the tranny. I've only had the boat for two years. 

 

Anyway, I am tempted to do the flush, but I'm afraid I'll spend $800 only to end up doing a rebuild regardless.

 

Tough choices ahead...

 

 

 

You have to get all the fluid out on these 8 speeds.  Can't just drop it once.  If you DIY it, just repeat the pan drop 3-4 times to get all the fluid out.

 

The original fluid in these was very hygroscopic (absorbed water).  The new fluid is not.  

 

Also.  Completely swapping the fluid out is A LOT cheaper than just throwing a transmission at it or rebuilding.  I'd rather roll the dice on $300 in the correct ATF for it and see if that fixes it first.  

 

 

Edited October 24, 2025 by newdude