04 tb 4.2 rough jolt when start or turn off.

[04trailblazer1991]

Hey so my 04 tb 4.2 4wd is great but when start it or shut it down the engine has a rough jolt when powers up or down... when turn key to start or turn off a almost bang without the noise...
Im thinking change the stock motor mounts. . Just wasnt sure if im missing something.. thanks for any input

 

[Mooseman]

Do you also feel a shake while idling or stopped at a light? That is also a sure indicator that it's the mounts.

Be sure to get only ACDelco mounts as the majority of the aftermarket ones aren't hydraulic as per the originals.

 

[mrrsm]

Roger That... These are the ones you want... Dealership Prices are in the '$85.00 a Piece' range ...but you don't want to have to do this job more than once:



When time permits... After Chocking the Front Wheels to avoid having a roll-away condition on an incline, elevate and support the Rear End on Jack Stands and examine-rotate the Drive Shaft(s) checking for any loose connections at the Universal Joints. Use a separate Hydraulic Jack to gently lift the Transmission while looking for a Failed Transmission Mount as well.

If the Motor Mounts have failed, you also might be experiencing an "Eye Teeth Rattling' sensation whenever at idle. If you look closely at the Inner Fender areas adjacent to the Motor Mounts from underneath the engine area (Motor Turned OFF), if the Rubber Ball MM Side Walls or Rubber Ball Carcasses of the Mounts have dried out and cracked through, then the repeated motions of the High Mileage Engine moving from left to right and back again during the normal rise and fall of Engine RPM and Torque might have squeezed them hard enough to fail:



This action can cause the Gooey Black Fluid to jet out through weakened rubber walls and decorate the areas nearby with a mess that is very *sticky* to the touch. This will be very obvious on the Driver's Side of the Engine in particular, since there is nothing "Oily" coming out of that side of the Engine capable of causing this kind of *stickum* deposition to occur.

It would be very helpful if you could also shoot a Short Video or Two with the SUV Hood raised and close enough to the Engine Compartment using either a Tripod Mount for your Camera or perhaps have a Friend shut of the ignition switch just as you film the events for us to look and listen more closely to this event.

 

[04trailblazer1991]

I ordered a ANCHOR kit. With 2 hydro mounts and a trans mount. Well see how that works...
But yea driving or in drive just a little vibrations no much.

 

[Mooseman]

Anchor has been shown in the past to cause vibrations.

 

[04trailblazer1991]

2K MILES IN AND I LOVE MY 60$ ANCHOR MOTOR MOUNT KIT! COST LESS than 1 gm. Still hydro. DO NOT LISTEN TO THIS OEM ONLY CRAP! that only applies to electronics only these days. Get what you pay for..BUT 60$ WAS ALL I NEEDED TO PAY... soooo smoooth! Easy install . I also changed struts n springs upfront. Only paid 50 each for spring strut combo n theyr awesome! Love rockauto... only issue ever had was with the cheapest tie rod end links. 3$ each... well those were lil off size but for 3$ what did i expect there.lol. stuff dont have to be gm but use your head. Thanks everyone who helpd!

 

[04trailblazer1991]

Anchor has been shown in the past to cause vibrations.

Idk he must of had other issues..

 

[Mooseman]

OK, just sayin' the experience we've had here for years on aftermarket mounts. Maybe they finally made them right.

I agree that we shouldn't pay overinflated prices for OEM parts IF there are good alternatives. I'm all for saving money but for some parts, it's not worth the waste of money and TIME.

Case in point, I recently replaced the inner tie rods on my '07 TB with Mevotechs that I bought years ago for my '02 TB but didn't need at that time. A month later, they were both shot. Lost time and money on renting the DIY shop again to replace them, this time with ACDelco Pro, not wanting to do it again as I have lost faith in just about every aftermarket name brand. Paid a little more but I just had that little bit of extra assurance and even then, I'm still not 100% sure.

Just speaking from lots of experience. If you're happy with your choice, then I'm happy for you.

 

[mrrsm]

For anyone visiting this Thread looking for the "How Do I DO This Job?" information... THIS Video is very instructive. The VOP (Video Original Poster) included a contemporary Link to the Recommended Factory ACDelco OEM Motor Mount(s) here at a Better Price:

Amazon.com

As for this...

"DO NOT LISTEN TO THIS OEM ONLY CRAP!"

Since the OP did not replace these components with the ACDelco OEM Parts...it is impossible to "Prove a Negative". For others in this situation, it is a bit too early to look so askance at such well-intended advice, which is what he came here for in the first place.

In general, for ANY repairs involving so much additional and difficult labor, suggesting to choose GM or ACDelco OEM Parts over anything else is a "Recommended Standard of Care" at GMTN that is in line with many other's empirical experiences. In the OP's present situation, it's really too early to tell or make such an affirmative (-) evaluation to make a fair comparison.

Time will tell...

PS...

One other advantage of visiting Amazon to look at these ACDelco OEM Motor Mounts are the 151 Additional "Ready-To-Read" Evaluations from Purchasers who also provide their own additional Tips & Tricks for doing this R&R. :>)

One Last Important Reason for Changing Out Failed Motor Mounts:

Collapsed, Gel-Filled Motor Mounts invite excessive forces being imparted into the Flex-Plate-to-Torque Converter, such that the motions of the unrestrained Engine Block and Transmission can cause Cracks to form around the Bolt Patterns of the Crankshaft. One Manufacturer advises that NOT replacing Motor Mounts AND the Transmission Mount whenever installing a NEW Replacement Flex-Plate... Automatically Voids their Warranty:

Zoom in on THIS Image... And See for Yourself:

 

[04trailblazer1991]

I was and am a bit happy about the situation. I dont mean any disrespect and totally understand!

 

[04trailblazer1991]

This whole 800$ 200k trailblazer has been cheap rockauto parts and now 6 months later all has come together sooo beautifully. Now i just need a new trans or someone to help with put a corvette servo in mine asap for this 2 3 slow shift!

 

[Mooseman]

You can start another thread for that particular problem in the appropriate section if you want.

 

[04trailblazer1991]

O no we are all done here for a bit lol! Thanks and understood