user456101

I have a 2000 Accord SE AT i4 (4-cyl) 180k miles. It is my daughters car and I don't want to waste any of her money as she is paying for it, so I am resisting just changing things without being as sure as possible. From a stop, especially when going up hill, there is an annoying amount of vibration in the dash that seems to get more pronounced as the engine revs higher and then peaks as the engine gets to about 2800 rpms. After shifting into the next gear, the vibration goes down but then begins to climb again with the climbing revs. When the car is in park/neutral at 2800 rpms the problem isn't there. Some vibration of course but much less vibration. Also, at highway speed it runs very smooth (the rpms are about 2200 at 60mph so maybe not a good test). If you think it might be an engine mount, I am curious which one you think it is. There are 4 on this model (front, back, right (actually the AT mount) and left (locations are from the drivers perspective). The mounts visually look fine, nothing broken and no significant cracks, but they all might be 16 years old now so... Is it more likely to be the transmission mount because the vibration seems to only happen when the transmission is engaged/the car is moving? Suggestions on how to test the mounts - remove for closer inspection or? If you say CV axle, would all of the symptoms I mentioned be explained by CV axles? If so,which one is it more likely to be right or left, or is it both? I looked at both and visually both look fine- the boots are in good shape at least. There are no funny sounds upon turning sharply either, and again, the vibration goes down, while accelerating, when the car shifts gears, so it seems less likely to my small brain that it is CV axles but then again I don't know much. I've spent a lot of time trying to logically figure this one out as you can tell and I would be grateful for some experienced advice before proceeding

MAD_MIKE

Have you checked for any stored codes?
When was the last time the car had a tuneup? Filters/plugs/wires/cap+rotor/valves adjusted/etc?
With 180Kmiles has the EGR system ever been cleaned?

Don't blame the trans mount. Left and right mounts support the engine/transmission. Front mount is a 'stopper' or limiter, it prevents excessive movement. Rear mount is the one that controls the application of torque from the power/drivetrain to the chassis.
With the car fully warmed up, open the hood and place the car in gear. Note movement, same when placing into reverse. Engine should load against the mounts but should not rotate excessively.

If you suspect the axles, or even wheel bearings, raise the left or right wheel off the ground, safely supported. With the opposite wheel on the ground. Turn the engine on, place in gear and allow the wheel to get up to speed. Be careful, as with one wheel on the ground the indicated speed on the speedometer is only half of what the one free wheel is actually spinning. Do not spin the free wheel faster than 30MPH indicated(60MPH actual), and gently bring the wheel to a stop. Don't abruptly stop it. Do the same for the other side. Any loud noises will be indicative of a failing wheel bearing or axle joint issue.