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Eddie, ASE Certified Technician
Category: Chevy
Satisfied Customers: 2998
Experience:  I have 20 years professional experience in advanced engine controls and transmission rebuilding.
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I have a 2004 Chevy Tahoe, about 190k miles, well

Customer Question

I have a 2004 Chevy Tahoe, about 190k miles, well maintained. I'm not very knowledgable about engines but I'll try my best to help describe my problem.
The truck cruises great and gears shift just fine, truck accelerates perfectly from 0.
When I am traveling around 40mph or more and let off the gas then press the gas pedal a little firm, like I want to give it sudden acceleration, the car will speed up but the engine makes a jolt or thud noise. Harder I push in gas pedal harder the jolt. If I just barely push in the gas pedal it will accelerate with no jolt. It kind of feels like when I really push in the gas it takes a second for the engine to respond and catches up and slips or jolts. Hard to explain but I can really feel it.
Submitted: 10 months ago.
Category: Chevy
Expert:  Eddie replied 10 months ago.

Hello, Eddie here and I will do my best to help. Have you seen a check engine light come on since you've noticed this problem any? Also, do the rpm's speed up and then when you get this jolt or thud noise, do the rpm's move down at the same time you hear this noise by chance?

Customer: replied 10 months ago.
No check engine light, I have not noticed the RPMs move at all.
Expert:  Eddie replied 10 months ago.

Alright, this in my opinion is likely either a transmission or engine mount, or possibly a U-joint, something shifting around causing slack in the driveline, will give you that thud. Now if the thud came after the rpm's goes up then "bang" the rpm's drop and you get that noise, then I'm going to say it's in the transmission internally, but you said there was no correlation between the RPM's dropping down and getting that thud right at the same time. So I believe it's in the driveline or transmission or engine mount. Try this, Put it in DRIVE, and with your foot on the brake, put it in R give it a little gas, then D give it a little more gas. See if you can make it do it then without even moving at all, that will tell us if the engine mounts are good or not, or if they are causing that thud noise.

Customer: replied 10 months ago.
Ok. I'll check it shortly. Seems like the truck shifts too well to be transmission but I wouldn't really know, I'm just hoping that's not the problem.
I know when I do put it in R I do get a thud noise. I'll do your test when I get a chance.
Expert:  Eddie replied 10 months ago.

Alright, let me know what happens there. thanks.

Expert:  Eddie replied 10 months ago.

Make sure the transmission fluid is full as well.

Customer: replied 10 months ago.
Fluid good. Only makes the jolt when I flip it to R
Expert:  Eddie replied 10 months ago.

So you can duplicate the noise just sitting still and moving it from D to R ?

Customer: replied 10 months ago.
It does sound like the noise but sometimes the noise is not as loud when I accelerate if I don't accelerate as hard.
Expert:  Eddie replied 10 months ago.

I follow you, Now in a perfect world, I would put the truck up on a lift, and get somebody in the truck to ride up in it and stall test it like your doing there, and look at the driveshaft and engine and transmission mounts, to see which one is making the noise, If it's a pingy metallic type noise, it's probably in the driveshaft or U joints, but if it's a thud, and you kind of feel it in your seat then I'm going to say it's probably an engine mount, and likely the driver's side, but the transmission mount can go to, as the transfer case puts more stress on the transmission mount. But in my opinion it is one of those things I've mentioned. Best case to find it, is take a flashlight and get it in the air and get someone in it to duplicate the noise while your looking and putting your hand on mounts and seeing what is moving and making the noise. Let me know if you have any further questions. Thanks.

Customer: replied 10 months ago.
I can feel it in my seat.
Is this something that could cause more problems?
Expert:  Eddie replied 10 months ago.

It likely won't cause more problems that it is causing right now because the rubber is worn out on the mount, but it really can't come apart as it has metal tabs which lock it in place, it's more of a nuisance than a safety concern in my opinion. If you plan on keeping the truck for a good while, I would likely get it fixed if it were mine. But it's nothing that has to be done right away.

Expert:  Eddie replied 10 months ago.

Please leave a positive rating if you feel I have helped. Let me know if you have any further questions. Thank you.