Several questions GMC NEWB

[James Hewitt]

I recently purchased a 2013 Yukon XL SLT with 144K. I have good service records for the car back to purchase. Spent almost al of its life as a program car shuttling to and from the airport and businesses.

The one thing I have-not been able to find in any service record was Transmission flush or service
My mechanic said without a history of that he would prefer not to do the service for fear of the transmission going out after. He said he didnt want to disturb the settling and sediment that was likely in there. He said he would do it if I agree to sign a waiver.

Question 1... Should I do a flush and clean or let it ride as he suggested? The fluid no longer has a red tint, it is full, and bo sediment coming through the stick.

I am currently experiencing a rather abrupt and loud clank from the rear of the vehicle. This only occurs after a stop and go. Not when going from park to drive, but only from drive - stop- and then go. When I took off the rear pass wheel and checked I could hold the hub at 3 and 9 and turn clock or counterclockwise and get a turn of about an inch each way. I can see thew drive train turning as I do it.

Question 2... In the spirit of KISS where should I start looking? (Keep it Simple Stupid) Drive shaft slip, dreaded chevy clank, transmission, U joints? I have changed the front brakes and rotors thus far. It is was easier to work on than my Land Rover was.

When I removed the rear Pass tire I noticed if I held the hub at 12 ad 6 I could pull on the top or bottom and get a tiny but of play. I know on the front end that is bad.

Question 3... On the rear is a little pal okay?

I am getting a little bit of a rough idle here and there. Nothing crazy and nothing that has effected performance thus far. I cleaned the intake manifold, checked all wiring, tubes, and hoses. I see no apparent issues. I have had no codes at all.

Question 4... What would cause the occasion rough idle?

Thanks for the help. I love this truck so far. Plenty of room for the kids and all their toys.


James

 

[thompsoj22]

i recently bought a 08 yukon denali 1500xl with 125k miles. i purchased it based upon car fax service records. it had a trans flush at 50k and 80k it is a little overdue at this point but still bright red in color. as your mech stated id probably leave it alone. discolored fluid is likely clutch friction plate material and there isnt much you can do, the clutches in autotrans wear also especially in city/towing driving. The 6 speed trans isnt a smooth shift when you are floating in the middle of accellerating/decelerating and the "subtle clank" is normal driveline ****** "IMO". my new to me 6.2 is not a silky smooth idle by any means, i think it is simply the nature of the beast. Bottom line, drive it gently for 10k miles and see what fails on its own, dont "fix it til it breaks" i have been guilty of this far to often. Flush the front/rear diffs, drain and fill the transfer case and enjoy your new ride, it will give you an opportunity to repair it eventually.

 

[swathdiver]

I recently purchased a 2013 Yukon XL SLT with 144K. ...The fluid no longer has a red tint

I am currently experiencing a rather abrupt and loud clank from the rear of the vehicle. This only occurs after a stop and go.

I am getting a little bit of a rough idle here and there.

Welcome aboard. If it doesn't smell burnt, the transmission fluid, I would do a fluid exchange. Did mine at 117K for the first time.

Check your u-joints but the center section of your rear differential may need an overhaul.

You need a good scan tool to properly and quickly diagnose and work on these vehicles. Get yourself a Tech2. You can check your Fuel Trims and see if that rough idle is a vacuum leak. Check all the connections between the air filter and throttle body and the emissions hoses on top and on the sides of intake/valve covers.

A subscription to AllDataDIY will give you access to the shop manual or you can buy it off ebay in pdf form. The books cost a fortune.