Grinding Noise & ABS Light

[YukonAlex]

Hello All,
New to this forum after picking up a 2002 Yukon from my sister with 118K miles about a month ago. After owning an Envoy and using the TrailVoy forum with great info, I quickly signed up on this forum and been lurking around for some general maintenance information. Since i got the Yukon, I've fixed an A/C leak and replaced rear A/C blend door actuator (AC blows ice cold now, front and rear) changed the oil/filter, buffed & polished it, changed the front brake pads/rotors (they lasted 118K..wow) and just put in new iridium plugs (ACDelcos).

I was about to do the rear brakes yesterday when i was driving back home on the freeway yesterday and as i was coming on to the off-ramp going about 45-50 mph, I felt the vehicle suddenly "disengage" and decelerate and the ABS and Traction Control (TC) Light came on. I cruised to a stop and as i made a turn and began to accelerate at about 10mph, there was a horrible grinding noise from beneath the front half of the vehicle and i quickly stopped again. I checked under the vehicle and no apparent oil or other fluids were leaking. I was able to accelerate to about 10-12 mph before the grinding would start again. I did this for 2 miles and was able to get home and park in the garage and reinspected beneath the vehicle, still no leaking oil or other fluids.

After doing some research online including TahoeYukon Forum (TYF), Some of the possible causes I could reasonably come up were: bad front or rear wheel bearings/hub assembly, bad wheel speed sensor, rear parking brake, bad ABS (ECBM) module, or transmission failure. Later that night, I decided to complete the rear brakes since i had already purchased everything. The parking brakes were completely done. This morning I tried to test the vehicle again and found I could not even back out of the garage, as soon as i put it in Reverse, I got horrible grinding noise again, even without the vehicle moving.

This is leading me to believe that it may be more of a transmission failure. But i don't understand the ABS connection and there is no dash lights on other than the ABS light, nothing on the OBD scanner or transmission light? I would think if there was a transmission failure, there would be some warning indicator light, but no lights other than the ABS and TC lights. If someone could please help with some more insight as to the possible cause, I would greatly appreciate any help or ideas on what else to check.

My Yukon is an SLT, 5.3L, 2WD, non-XL and bought new from dealer by my sister who used it in the relatively mild climate of Southern Cal in the LA area. It was well taken care of and never used for towing or abused otherwise. Sorry for the the long first post, just wanted to include all the details i could about my current problem.

 

[afpj]

If it makes that noise while standing still just putting the transmission into gear, and you have 2 Wheel Dr., you may have guessed it right transmission. Have you looked at the quality of the tranny fluid?

 

[YukonAlex]

Thank you for the reply, yes, I'm fearing its a transmission problem. The grinding is also only when i select Reverse, no grinding when the Drive gear is selected. I have not checked the tranny fluid. My brother-in-law told me he recently had the rear diff. fluid changed along with the valve cover gasket. The vehicle was driven very little for the last 3 years because they got a new vehicle and basically stopped using the Yukon. A sticker on the window has the date of the last oil and mileage, it was 3 years ago and only driven about 300 miles until i started using it about a month ago, needless to say, i changed the oil. Not sure if this would degrade any other components to the point of causing transmission failure. He did tell me he had the tranny fluid change at one point but could not recall at what mileage.

Today i inspected the drive train more closely and saw the drive shaft appeared to have slid out a bit from the transmission. Any insight on what might cause the shaft to slide out that far?


I also noticed the Starter was covered with oil significantly which at first glance does not look like motor oil, but I'm not certain.

 

[afpj]

Tranny fluid level OK? There are some tranny experts to on this forum hopefully they can chime in. You might do search as I recall reading something similar sometime in the past (reverse issues). That pic is too dark on my phone but it may be normal yoke slip. Sorry, my knowledge on this has been exceeded. Please deposit another quarter to continue...
as for the oil on the starter, that may have been from the valve cover leak just left over as I had that before.wipe it down and keep an eye on it.if your brother in law used a cheap ass gasket for the valve cover, it may already be leaking. Don't ask how I know.

 

[livingez_123]

The driveshaft does slide in and out of the trans about 1/2-3/4" under normal driving. It sounds like the trans is toast. I would drop the pan and see if there is any metal chunks in the pan. You also say it only does it in reverse, again it leads me to the trans. You might try to jack up the rear of the rig and put it on jack stands, try to rotate the wheels and see if you hear any noise. It also wouldn't hurt to pull the rear diff cover off and change the fluid and see it its ok in there.

 

[YukonAlex]

i checked the transmission fluid level when cold only, and it was very high!, above the 'Warm' level when cold the level should be a lot lower then the 'warm' level. I will check again when warm and idling to verify if the level is indeed very high. Would too much tranny fluid cause the shaft to disengage? the shaft has come out about 2-3 inches as shown in the photo above. Is it possible there is some bearing in the diff or other component that failed to cause the shaft to slide out? I will open the diff. and tranny, but have to work this weekend so won't be tip following weekend.
Thanks for the replies.

 

[YukonAlex]

Transmission fluid level was fine when checked warm, while idling and car in Park. I've been doing more research here and other online sources and now suspect it is a bad sun gear shell which is apparently what causes the 2nd, 4th and reverse gears not to engage, or my case, grind. I verified this further after I lifted the rear end, started her up and was able to put the tranny in 1st, 3rd and Drive with out any issues, 2nd and reverse gears would grind when trying to engage.

I've never had such terrible luck, I've owned it for less than 2 months and drove it just over 300 miles and the transmission goes out? Apparently this is a known issue with GM transmissions and weak teeth on the sun gear shell. There is a heavy duty "Beast" sun shell I should look into. So, to rebuild with heavy duty sun shell gear or or get rebuilt transmission?

 

[livingez_123]

If your going to have it apart, I would rebuild the entire trans. Sonnex also has a very good sun shell on the market that is even better than the Beast.

 

[YukonAlex]

So I've decided to take the plunge and dropped the tranny this weekend, took me two long days by myself with a couple of trips in between to the store for a couple of tools (i.e. lots of extensions, transmission jack, etc.) and a few hours to spend with the Mrs. i know its longer than it should've been, but i like to take my time and make sure i don't break anything, like this plastic electrical connectors. Also, my cheap Harbor freight creeper gave out on me and really made it even more of a PITA jobs, guess its time for a quality upgrade.

Anyways, I've never removed a transmission before, let alone rebuild one, but thats exactly what i intend to attempt. Ive been watching hours of 4l60e rebuild videos and instructions and although at first it seemed like a suicide mission, the more i watched, the more i got confident i could pull it off.

Any comments, tips, advice, experience, pro or con, are welcome. Also, suggestions on which rebuild kit (alto vs borg warner, or others) also which sun gear shell (the beast vs sonnax vs oem hardened).

Also, i've been reading about most upgrade other components such as corvette servo and aluminum (and pin less) forward accumulator. Are these worthy upgrades? I'm really only interested in upgrading for heavy duty purposes instead of performance, but achieving both never hurts.

Thanks in advance for your inputs.

 

[livingez_123]

The biggest thing I can say is to make sure you clearance your clutch packs properly and to use plenty of lube when installing your piston seals. Make sure you don't cut or nick any of the rubber seals. use a good press tool for the clutch packs.