Q: Four-wheel drive GMC Denali with a 5.7 liter. It has lost reverse and makes a very loud grinding noise when put in any gear. 1999 GMC Yukon Denali

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Very loud grinding noise when put in any gear reverse does not work only 3rd and 4th gear work grinding noises only while in gear

My car has 150000 miles.
My car has an automatic transmission.

Hi there. The noise that you are hearing is something broken in your transmission. It sounds like the gears have damaged teeth on them and there are multiple clutches that are not applying. The transmission will need to be rebuilt or replaced. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your transmission grinding issue.

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Hi there - first task is to check for adequate fluid level and for burnt fluid. Should be red and semi-clear. If fluid is at the level, and looks OK, it’s quite likely you have lost the lo-reverse clutch pack, with possibly other damage. I would recommend a transmission inspection by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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