Clunk when almost stopped.

Donstar · November 27, 2019

On Sunday my wife and I ran several errands with the truck. We both heard and felt a distinct clunk when coming to a stop at an intersection. This occurred just about at every stop so Monday morning I made an appointment to have it repaired. My appointment was yesterday (Tuesday) but of course my truck quit clunking prior to my appointment. We all know that if they can't hear it or see it then ….. My question is what can cause an obvious mechanical flaw like this be intermittent. I understand how something like a small leak in a radiator will sometimes subside but this "clunk" sounds like a substantial malfunction. I know there are threads about transmission clunks but I'm asking for the Coles notes on the reasons for this being a sometimes occurrence. Thanks.

VdellaV · November 28, 2019

Pretty sure it could be a little slack on the Yokes of the Driveshaft.

You can check yourself by going under the truck and manually trying to turn the shaft to see if it has excessive play

CKNSLS · November 29, 2019

This "clunk" is a standard feature of your truck. There may or may not be fixes. It could be drive line, rear springs-but GM doesn't really have a permanent fix.

Donstar · November 29, 2019

13 hours ago, CKNSLS said:

This "clunk" is a standard feature of your truck. There may or may not be fixes. It could be drive line, rear springs-but GM doesn't really have a permanent fix.

I consider myself to have an average or better appreciation of most things mechanical. I can accept unexpected breakdowns but when they appear to go away on their own I get unsettled. "A little slack in the yokes" as an example is a good possibility but how could this be problematic for a day and then be fine for a week? I've had aches and pains go away as soon as I make an appointment to see a Doctor. However, the complexities of a pickup truck have not reached the level of the human brain! I do know there is a lot that I don't know. The fact that my dealer won't attempt, at this time, to fix the problem suggests that they know something. They believe me that I had a problem, but because the service advisor didn't hear it, he can't authorize a repair. Fortunately Doctors don't work like this!

CKNSLS · November 29, 2019

8 hours ago, Donstar said:

I consider myself to have an average or better appreciation of most things mechanical. I can accept unexpected breakdowns but when they appear to go away on their own I get unsettled. "A little slack in the yokes" as an example is a good possibility but how could this be problematic for a day and then be fine for a week? I've had aches and pains go away as soon as I make an appointment to see a Doctor. However, the complexities of a pickup truck have not reached the level of the human brain! I do know there is a lot that I don't know. The fact that my dealer won't attempt, at this time, to fix the problem suggests that they know something. They believe me that I had a problem, but because the service advisor didn't hear it, he can't authorize a repair. Fortunately Doctors don't work like this!

With all due respect-your dealer will not attempt a fix because there isn't one.

tbarn · November 30, 2019

It's not about authorizing a repair. If they drive and cannot duplicate the noise, what parts should they throw at it. And doctors DO work like that. "Hey doc, I didn't feel well last week, I feel fine know though what was wrong with me. ". How is he supposed to know. He will take your money though and send you on your way.

rocksolid1224 · November 30, 2019

remove driveshaft and apply a light coat of wheel bearing grease to plines, on front yoke and reinstall shaft

CKNSLS · December 1, 2019

On 11/29/2019 at 6:22 PM, rocksolid1224 said:

remove driveshaft and apply a light coat of wheel bearing grease to plines, on front yoke and reinstall shaft

Again-this is not a permanent fix as reported on various truck forums.

Donstar · December 2, 2019

On 11/29/2019 at 4:06 PM, tbarn said:

It's not about authorizing a repair. If they drive and cannot duplicate the noise, what parts should they throw at it. And doctors DO work like that. "Hey doc, I didn't feel well last week, I feel fine know though what was wrong with me. ". How is he supposed to know. He will take your money though and send you on your way.

Ideally this is the way it should work. I remember when I experienced water intrusion and they couldn't replicate. The fact that my foot was getting wet on rainy days had to be experienced by the service advisor. The second time I took it in they just took my word and replaced the shark fin. This is simply one example but pretty standard. I fully expect they'll check further into my clunking complaint when I experience it again. The Doctor analogy is a little different. Just because pain subsides doesn't mean the problem has disappeared. When I visit my Doctor with a concern he looks for the cause and has an explanation if no cause can be found.

6_2LTZ · December 2, 2019

Two trucks. Two same clunks. Some days are good. Some days are bad.

mnm99 · December 13, 2019

What transmission do you have? I bet it's an 8 speed. The downshift clunk is a known problem. It comes and goes. I had mine in the shop 4 times and they said either they didn't hear anything or it's normal. The 5th time I drove with them. The tech heard it and they ended up doing a flush and valve body replacement. 100+ miles it was fine, now it's back with the addition of a 5th gear clunk too. GM knows about it, but won't do anything about it.

http://gmauthority.com/blog/2019/09/lawsuit-alleges-gm-transmission-problems-known-since-2014/

Edited December 13, 2019 by mnm99

CKNSLS · December 13, 2019

42 minutes ago, mnm99 said:

What transmission do you have? I bet it's an 8 speed. The downshift clunk is a known problem. It comes and goes. I had mine in the shop 4 times and they said either they didn't hear anything or it's normal. The 5th time I drove with them. The tech heard it and they ended up doing a flush and valve body replacement. 100+ miles it was fine, now it's back with the addition of a 5th gear clunk too. GM knows about it, but won't do anything about it.

http://gmauthority.com/blog/2019/09/lawsuit-alleges-gm-transmission-problems-known-since-2014/

It's a known problem of the 6th speeds as well.

Donstar · December 13, 2019

1 hour ago, mnm99 said:

What transmission do you have?

54 minutes ago, CKNSLS said:

It's a known problem of the 6th speeds as well.

I have the 6 spd. It is currently behaving. I am sure it is waiting for an inconvenient time to resume clunking!

CKNSLS · December 13, 2019

9 minutes ago, Donstar said:

I have the 6 spd. It is currently behaving. I am sure it is waiting for an inconvenient time to resume clunking!

I have a 2018 LTZ-4WD Crew Cab w/the 6 speed and 5.3. This truck had an MSRP of $52,000.00 (although I didn't pay anywhere near that) you would think GM could make a better drive train. I call all the 6 speed trucks the "clunk-O-matic!"

Mozzer · December 14, 2019

Most likely shows up more when braking hard to an almost stop, I think the downshifting is playing catch up with the speed, might help in demonstrating to dealer.

2014, 5.3, 4x4, work truck