Motor mounts?

[c0a8l0v6i8n9]

Recently my truck vibrates you can feel it even if you touch the tires. When accelerating it vibrates for a second then stops. If I put it in neutral the vibration lessens. If I turn right the vibrations gets worse and left hand turns it goes away.

This seemed to happen one night I was reversing in 4HI and as the tires were spinning through the sand I heard a wack wack wack sound as if someone was hitting something with a hammer.

The other day it stopped vibrating I was going uphill and made a right out of a parking lot l. I heard that same hammer hit sound and it went away but has now returned.

I'm thinking motor mounts. Any suggestions?

[ErikSS]

If I turn right the vibrations gets worse and left hand turns it goes away.

That sounds like a left front wheel bearing problem to me. Jack it up, spin that wheel and listen. Also I grab the tire at the bottom and top and try to wiggle for play.

[c0a8l0v6i8n9]

I doubt it's the bearings they are about 5k miles old. It vibrates at about 1300 rpm the worse in gear or not in gear.

[Moots1288]

I doubt it's the bearings they are about 5k miles old. It vibrates at about 1300 rpm the worse in gear or not in gear.

doesn't matter how old they are. My moog wheel hub went on the way to tecore with about 2k on it.

[ErikSS]

Do you have G80?

Edit: Nevermind. I see your build sheet says no do not have G80. I was wondering if that's what you were feeling in reverse in sand but obviously not. Sorry! Wheel bearing is still what I would check first as the platform is known to be hard on them.

[c0a8l0v6i8n9]

If it was a wheel bearing why does it shake and vibrate in park

[Moots1288]

If it was a wheel bearing why does it shake and vibrate in park

how hard is the vibration?

[ErikSS]

If it was a wheel bearing why does it shake and vibrate in park

It wouldn't. So it vibrates while sitting still, but goes away when you turn left? Sorry man, I'm at a loss.

[c0a8l0v6i8n9]

The vibration is very noticeable

[The Roadie]

A 10 Hertz rotational vibration you can see by looking at the PCM, that's worse in DRIVE than PARK, is motor mounts.

The vibration you feel while driving may be the bearing, or more likely a borked CV shaft. CVs are cheaper than bearings.

[Trail X]

True, its possible that there are two vibrations working together to produce the symptoms.

Have you inspected your motor mounts? Check for fluid coming out of them, or one significantly deflated compared to the other. Does the engine seem to shake badly, as roadie said?

Does the shake/vibration seem to get worse at any specific speeds of travel? Have you inspected your front suspension for torn boots or other worn components?

[c0a8l0v6i8n9]

I'm going to try to check the mounts tomorrow. I didn't notice any fluid loss from the mounts. The CV on my passenger side is about 1000 miles old. Could it be a defective shaft?

The vibration is the first second of take off then it goes away. The moment I hit the gas it will vibrate then disappear and not return until I'm at a full stop.

[v7guy]

Calvin, this is pretty much the exact symptoms of the ole motor mounts being junk. Your description matches everything I've read while researching my bad motor mounts and it mirrors my experience when I suddenly got a vibration with the motor runnin. As Bill said, it all has to do with the natural vibrations of the motor and it's pretty damn specific in the rpm range. Quite the quirk of the ole I6.
I didn't see any leaky fluid on the mount when I replaced it until I pulled it out. When it was out and compared to the old mounts it was obvious that it was significantly degraded. no doubt at all, torn, leaky, and collapsed a good bit. Installed the bad mount looked fine. It's particularly important to note that you want OEM replacements. Everything else seems to make the vibrations worse or offer no improvement.


You'll also find that if you dig around enough a rock in the transmission mount can cause these exact symptoms. So it's the first thing to check. Even though it's cold as frack.

[c0a8l0v6i8n9]

Calvin, this is pretty much the exact symptoms of the ole motor mounts being junk. Your description matches everything I've read while researching my bad motor mounts and it mirrors my experience when I suddenly got a vibration with the motor runnin. As Bill said, it all has to do with the natural vibrations of the motor and it's pretty damn specific in the rpm range. Quite the quirk of the ole I6.
I didn't see any leaky fluid on the mount when I replaced it until I pulled it out. When it was out and compared to the old mounts it was obvious that it was significantly degraded. no doubt at all, torn, leaky, and collapsed a good bit. Installed the bad mount looked fine. It's particularly important to note that you want OEM replacements. Everything else seems to make the vibrations worse or offer no improvement.


You'll also find that if you dig around enough a rock in the transmission mount can cause these exact symptoms. So it's the first thing to check. Even though it's cold as frack.

Thanks Jason. I figured it was probably my mounts I will check for a rock in the tranny mount and hope that's the case but in my life nothing is that simple. The mounts will have to wait till spring.