02' LT Transmission Doing Strange Things

[kennethtyler26]

I have a 5.3L 2002 LT Tahoe 4x4 (automatic). It has 232,000 miles.

I've babied this thing since 2006, all synthetic fluids and regular changes. I've changed nearly every part out on the engine, with the newest job being catalytic converts, water pump and fan clutch.

What's happening right now in Louisville, KY is that it's -4 degrees at night time and 14 degrees during the day. So I'm wondering if this has anything to do with cold weather.

Before it was cold, my Tahoe would do this thing where you had to put it into 1st or 2nd manually for it to shift into gear. If you put it into drive, it would rev up and not move. If you revved it up hard enough it would slam into first. I didn't like doing that so i just baby'ed it by getting up to speed in 2nd before putting it into drive. Once the truck went a few miles, it would shift properly. Not sure if it was warming up, or what.

Today, it was 14 degrees out and the truck sat outside overnight. The manual shift into 1st or 2nd wasn't working the way it normally would. Additionally, I started to hear a slight grinding noise in certain gears (mainly 3rd). At one point there was a strange sound at about 30mph, it sounded like a slow spinning fan blade and someone sticking a thin piece of metal into the fan. I think it was the top end of third when I heard this.

After accelerating onto the interstate, the best description I could give is that it seemed to be confused as to what gear to go into. The engine would rev but the truck wouldn't have power, and then halfway into accelerating it would grab and go.

The final weird thing is that I cruised for about 20 minutes on the interstate at 70 mph and it NEVER shifted into OD. I was locked in at about 3k rpm at 70 mph.

Once I got off the interstate and came to a stop, it accelerated fine after that. No noises, no weird shifts, etc.

Can anyone tell me what the heck is going on? I opted to not change the transmission fluid when this whole thing started because several mechanics said the new fluid could blow the seals and mess everything up. I have no idea what the problem might be, and if it's weather related or something more.

Thoughts?

 

[OR VietVet]

If you are running synthetic trans fluid, like you indicated early in the post, I don't think the fluid and filter change would hurt anything but it sounds like you are past that. I assume you have no CEL since you didn't say. Sounds like a valve body problem at first but with the noises I thing you have a roller clutch coming apart. With that many miles on it, it may be just time to bite the bullet and get it done. A trained trans tech needs to check it though. Now you need to decide that if it is in good shape and you have done all the engine work and have no probs there and it meets your needs, do you spring for the money if the trans is needed?

 

[TheAutumnWind]

I'm not sure how new fluid could blow seals. Sounds like they didn't want to be liable.

I would do a pan drop, and not a flush. Forced Transmission flushes is what causes problems. Worst case scenario you find a ton of material in the bottom of the pan and you know its gone.

 

[kennethtyler26]

Thanks for this information! You're right, I need to have a trans tech take a look.

Could a roller clutch coming apart still allow the transmission to run smoothly once warmed up? I'm curious why I was hearing strange noises and then suddenly it was gone after warming up.

Also, is there some kind of computer safety feature where OD is bypassed in cold temperatures?

My final question for you guys, being you are well versed in this, would be price ranges for a re-built transmission with labor. What's my high end / low end range to look for on something like that?

Thanks so much!

 

[OR VietVet]

Without knowing exactly what is wrong and not dropping the pan yet to see if has debris in it, it would be hard to say. The noise could be because of the cold causing something to work even slower than normal and therefore causing a list of slightly different problems. Right now all we are doing is guessing. We know of the miles, the fluid is hopefully full-you didn't say, what a shop is not willing to do-by the way-now days the trans flush equipment typically uses the trans pump to move the fluid thru the trans so is not forced but I am sure there is still some equipment out there that forces, what you experienced before and now in the extreme cold and that you are not comfortable driving it.

IMO I would never use anything but Jasper engines and trans for replacement. They build a superior product and have never had to take a Jasper product back out of a rig. They are not cheap but I like to do it once and do it right and be done with it. Again, IMO.

 

[kennethtyler26]

Thanks so much for the advice and help!

I've called a trusted mechanic who said he could put a rebuild in for $1,500 labor included. However, I have a family member who is a trans tech for diesel trucks. He apparently has done several GMC/Chevy trucks in the past and says he could do the re-build for me. He said cost on parts for him are like $350. Should I research cost on Jasper products and have him install that?

I think you're right - I'd rather do this once and not multiple times. Ha!

Thanks again.

 

[OR VietVet]

Guarantee the Jasper trans will be more. The relative that is trained and knows what he is doing should be a great idea. Make sure you get a new torque convertor and flush out the cooling system. Start out with synthetic fluid and stay there since you have the good luck with it. Can the relative also diagnose the problem?