Feels like something slips, but only at part throttle

[Rocket Man]

I think I found my problem. I did the motor mount test today and I feel this same thud when the engine raises a couple inches on the drivers side.

So, guess new mounts are in the near future

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Well I guess it’s good that you found the problem but it kind of sucks that’s it’s not an easier fix. Are you going with the Hummer mount?

 

[gooffeyguy]

Well I guess it’s good that you found the problem but it kind of sucks that’s it’s not an easier fix. Are you going with the Hummer mount?

Yeah, I ordered the H3 mount from RA.

I'm rather relieved that it's a bad mount and not something else like a loose transfer case chain or something more complicated or expensive.



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[Rocket Man]

Yeah, I ordered the H3 mount from RA.

I'm rather relieved that it's a bad mount and not something else like a loose transfer case chain or something more complicated or expensive.



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Yeah i guess it could have been way worse.

 

[ivin74]

Yeah, I ordered the H3 mount from RA.

I'm rather relieved that it's a bad mount and not something else like a loose transfer case chain or something more complicated or expensive.



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Did the motor mount fix your issue?

 

[RuggedGMT400800]

Had similar symptoms on our ‘07 Denali. Replacing the transfer case helped and a new front differential took care of the rest. Also had the pinion bearing/seal on the rear differential replaced in the process.

It's the rear Pinon that causes this. Front diff nothing to do with it and trans case won't wind up like that otherwise it'd be loud grind or shriek... dealership replacing or pretending to replace unnecessary major components for a gullible, trusting, or foolish client. They replaced the 22$ 10 minute seal then charged many thousands for nonsense.. maybe just wiped the front diff and trans case down with a rage and put a few grand in pocket.

 

[91RS]

It's the rear Pinon that causes this. Front diff nothing to do with it and trans case won't wind up like that otherwise it'd be loud grind or shriek... dealership replacing or pretending to replace unnecessary major components for a gullible, trusting, or foolish client. They replaced the 22$ 10 minute seal then charged many thousands for nonsense.. maybe just wiped the front diff and trans case down with a rage and put a few grand in pocket.

Were you there? Unless you were there and have proof of that happening, you have no clue what you’re talking about.

 

[gooffeyguy]

Did the motor mount fix your issue?

Yes

 

[wjburken]

It's the rear Pinon that causes this. Front diff nothing to do with it and trans case won't wind up like that otherwise it'd be loud grind or shriek... dealership replacing or pretending to replace unnecessary major components for a gullible, trusting, or foolish client. They replaced the 22$ 10 minute seal then charged many thousands for nonsense.. maybe just wiped the front diff and trans case down with a rage and put a few grand in pocket.

Easy there big shooter! Might want to hold off on throwing out comments like this here. No dealer involved to take advantage of a foolish client. I do my own diagnosing and repairs and do not just throw parts at problems. Got that 2007 to 300K that way. I know for a fact this solved my problem. If you were able to fix your issue with a $22 seal, that’s great.

 

[RuggedGMT400800]

Neithe

Were you there? Unless you were there and have proof of that happening, you have no clue what you’re talking about.

Neither the transfer case nor the front diff causes the symptoms described.. however, the symptoms described is exactly spot on consistent with what a failed crush sleeve (reduces or eliminates pinon preload) and/or a backed off pinon nut/ improperly torqued Pinon nut.
What happens is when using go to accelerate you'll get a slip followed by a tailbump caused by the rear driveshaft starting to spin prior to engaging the ring gear due to aforementioned worn/damaged Pinon seal/crushsleeve and the play it creates. As it rotates and inertia drives it rearward back to where it normally belongs in proper permanent engagement..

Makes perfect sense to me.. I've replaced several dozen Pinon assemblies on gmt400 and gmt800 as well as have rebuilt many transfer cases as well. And have had my fair share of hundreds of hours with front diffs on the bench and in hand.. so no sir, needing to be there to watch someone who may have known better st the time or was in a vulnerable situation and in need of immediate repair without regard to sensible reasoning of the symptoms vs the proposed repair, fork over money unfairly suckered from him is not necessary for diagnosis. No disrespect intended.. Was more upset knowing thrbdealer took you for a couple grand than anything else, I didn't mean to come off with a bad demeanor and my appologies for doing so as I realize I was a little bothered when I wrote that, my mistake