Harsh shake at shut-down

[JD3020]

This is something my truck has done for a while, but never paid attention to it. Then the last couple days i've spent some time in a couple different SD 7.3's and i noticed they didn't do it, so now i'm thinking about my truck.

Problem is at shut-down my truck has a very harsh shake. It has a bit of a miss(i think) at an idle, and a shake to it, but its a 200k mile OBS so its nothing that really bothers me too much anymore. All injectors buzz fine, and up until recently it'd pass CCT with flying colors, now its failing #8. Had a bad fuel leak so today i replaced the fuel pump and it runs better. But still, when you turn it off it has a harsh shake, kinda hard to describe. Like it'll rock the truck.

I've read around some, and it seems common with failing DMF's, but i've got an auto. Otherwise i haven't really found much.

So what could be causing this?

 

[JD3020]

Did some more searching last night and still haven't found much on this, but could loose or worn-out engine mounts or the rear trans mount cause this?

 

[JD3020]

Anybody have an idea?

 

[bad12jr]

Check the torque converter bolts. Mine were loose not to long ago and were doing similar but it also had a resonance vibration in the drivetrain at certain engine load.

Sent from my x2 somewhere

 

[JD3020]

I have not checked mine but will once it quits raining. But the only driveline issue i have is a bad clunk when the converter locked, no real vibrations or anything.

 

[JD3020]

Bumping this back up. Basically parked the truck before Halloween and now it i only drive it if i have to, which isn't very often anyways. But i've been driving my '90 which compared to my 7.3 runs very smooth. Never realized it until i spent a week driving it then i hopped in the 7.3, shakey idle and really harsh at shut down. Getting ready to go out now and do some stuff to it and check the converter bolts. But i'm confident that they are tight.

So what else could be causing this?

 

[littleredstroker]

Motor mounts/ trans mounts

sent while trying not to blow PMRs

 

[JD3020]

May replace the trans mount as IDK if it got replaced during the trans rebuild last winter, and i think i can still get em cheap.

But how can i check the engine mounts?

 

[Jarrod B]

Sure the engine is not a cummins?


jkjk

 

[JD3020]

LOL LOL

Surprisingly our 1st gen 5.9 doesn't have the shake, but my 7.3 does. :morons:

 

[JD3020]

Small update.

Don't have a long pry bar here but i went ahead and did a quick check. Driverside i could only reach the oil cooler and couldn't get much leverage, but i couldn't get any sort of movement. Passenger side i could get good leverage on the manifold and can rock the engine up and down some, but not maybe. Maybe 1/4" in total movement. So i assume that should be solid like the driver side, correct?

On my way to my brothers to work on the 3020 so i'll grab a long bar and check it some more.


Also, may or may not be related, but when driving, converter locked, if i get on and off the throttle i feel and hear a clunk in the driveline. Seems to get worse at lower speeds, really bad down around 25mph or so. With the converter unlocked there seems to be no clunk. Just throwing that out there in case it could be related to the other issues.

 

[TyCorr]

Sounds like you've got loose bolts to get tightened.

 

[littleredstroker]

I WON!?!

sent while trying not to blow PMRs

 

[JD3020]

Went through it last night. Converter bolts are tight. Couldn't reach the top trans bolts but all the others were tight, except the lower driverside bolt. It was loose. Seems to have helped slightly, but last night was not a good night so i didn't really pay any attention to how the truck was acting.

 

[Wes Lewis]

Maybe the body mounts?

 

[JD3020]

Cab mounts are good, except the front core support mounts but the core support is about gone so they don't matter much. LOL

Only thing i can think of that could be left would be engine/trans mounts, or something on the engine itself.

 

[littleredstroker]

Maybe have a buddy shut it off a few times to see if you can look and specifically see what's shaking

sent while trying not to blow PMRs

 

[TyCorr]

Maybe have a buddy shut it off a few times to see if you can look and specifically see what's shaking

sent while trying not to blow PMRs

Yea. Most of.this stuff requires a little thought and some work to see. I'd listen and see where the noise is coming from. Under the hood, under the cab, etc. If need be, take the hood off get in and shut it off. The motor looks like it's about to jump out.the friggin engine bay. Hey, maybe my motor mounts are shot. Or get a wrench and check the damn converter bolts.

We can name places where loose connections could occur all day long but until he checks something, we're wasting time.

 

[JD3020]

Yea. Most of.this stuff requires a little thought and some work to see. I'd listen and see where the noise is coming from. Under the hood, under the cab, etc. If need be, take the hood off get in and shut it off. The motor looks like it's about to jump out.the friggin engine bay. Hey, maybe my motor mounts are shot. Or get a wrench and check the damn converter bolts.

We can name places where loose connections could occur all day long but until he checks something, we're wasting time.

I checked the bolts, they are tight.

 

[Bustedknuckles]

Have someone powerbrake it and watch under the hood to see if the engine torques up.