YIKES! 97 F250 SHAKES! motorheads help me plz!

[Boondocker]

My 97 F250 PSD has taken to shaking like crap off and on. I suspect that it may be an issue of how the motor is (or isnt) mounted to the frame. Does this make sense and what should I look at to find the problem?

[Boondocker]

The reason I am inclined to think it may be the mounting rather than the running gear (for lack of better terms) is that the shakes seem to be linked to RPM rather than movement per se. It is more common up hill and under load. Down hill even towing the vibration-shaking goes away. If you slow way down and let the shaking stop, you can sometimes speed back up (if you avoid RPMs over 2500) without it shaking.

What other details are needed to diagnosis this?

[war eagle]

Some additional information that might help...
Is the truck 4 wheel drive?
Any recent changes such as: front end alignment, new shocks, new tires, or tire rotation?
How many miles on the truck?

Steve

[Boondocker]

Originally Posted by war eagle

Some additional information that might help...
Is the truck 4 wheel drive?
Any recent changes such as: front end alignment, new shocks, new tires, or tire rotation?
How many miles on the truck?

Steve

2 wheel drive, no recent changes, about 200K miles. Standard transmission

[easyride]

Sometimes a Ujoint will act like that,jack up one rear wheel,and see if you have play in the drive shaft,if is 4x4 jack up one of the front and try the same thing. Dave

[Boondocker]

Originally Posted by easyride

Sometimes a Ujoint will act like that

I'm not sure why that would be, the vibration remains constant (relative to RPM) and is not a clunk when engaged. What am I missing?

[Aviator]

Check your engine mounts, it sounds like one my be cracked or broken.

[tpi]

If you hold the brake firmly and let out the clutch slowly (1st gear) does the engine lift excessively on the left side? That would be typical of bad engine mount-as that mount takes most of the torque. The other mount or the rear mount at transmission could also be broken.

[Boondocker]

Originally Posted by Aviator

Check your engine mounts, it sounds like one my be cracked or broken.

How does one do that?

[clancy_boy]

Check for a possible clogged fuel injector - a rough running diesel can feel like the truck is shaking apart. I had a shot #8 cylinder injector - fuel economy went way down - sluggish starts - idled OK but at highway speeds I had a loss of performance. All three O-rings were burned through (?) and the injector was burnt. I change my fuel filters at 15-20K mile intervals. The fuel pump went out too. I had 150K miles on the truck. This is a 7.3PSD - I would not change the vehicle for a new one, "FLO" is a great truck.

[HiHoAgRV]

Originally Posted by Boondocker

I'm not sure why that would be, the vibration remains constant (relative to RPM) and is not a clunk when engaged. What am I missing?

I'm not convinced a ujoint IS the problem, but they are easy to eliminate...
Slack is one problem and can be found by wigglin, but look real close for rust on each cup seal...I had one cup full of needle bearings go dry, jam up and vibrate. The rusty dust coming from the cup seal was the giveaway.

One thing for sure...an ignored vibration has never fixed it's self for me...its always a clue that something is just gonna get worse...

[Boondocker]

Originally Posted by clancy_boy

Check for a possible clogged fuel injector .

OK, not to be an obvious dunce, but how does one check for a clogged fuel injector?

[Jim & Susan]

When's the last time you had yer running gear balanced?

Seriously, my work truck (provided by the company, I do NOT own this truck) is a '98 E250 van, a bona fide piece of junk because of poor maintenance. Vibrates very badly around 45 to 50 MPH. The problems IS the tires. The tires are cheap "foreign made" tires that the company won't replace because they have too much tread left on them. Corporate idiots.

I personally own a '97 & '98 F150 that will vibrate very badly if the front brake disks warp (happened a couple of times thru the years). Any reason to believe that the rotors are warped?

I would think you could have the motor mounts inspected at a shop for little or nothing.

Interesting thread. I'll be following along.

Jim

[r carl]

Originally Posted by Boondocker

How does one do that?

Be in first gear with clutch in, emergency brake on, and with the heal of your right foot push the brake pedal down hard and with your toe press the throttle a little and with your left foot let up on the clutch until it puts a load on the engine, the drivers side of the engine will try to lift up. If the mount is broke it will lift up more than an inch. Some mounts nowdays are interlocking and wont let the engine come up far enough for the fan to hit the shroud.

[PLDodd]

Does it seem to be speed related? Most older Ford trucks need a steering damper or the original replaced (if equipped, if not you can buy an aftermarket add on kit) Typically when the steering gearbox has alot of wear the front end will shake violently at high speed after hitting a bump in the road. usually it will not go away until you slow down or stop. Combine worn tires, worn out or loose steering gearbox and worn out or no steering damper that is what you get. You can usually adjust the gearbox (just a little, too much will make the steering tight & not return to center, about 1/2 turn to 1 turn should do) replace or add a steering damper, get the front wheels balanced if the tires are in good shape and that should do it.

[war eagle]

Agree with PLDodd, it seems that the "shimmy" or "death wobble" as it is often called is often from a combination of wear related issues in the front end of the truck. The cure for my 2003 2 wheel drive F250 was a front end alignment that included an adjustment of the steering box. I also replaced the radius arm bushings. The Ford Truck Enthusiast forums are a great source of info on the subject though much of the information there relates to 4 wheel drive trucks so mine data carefully for your 2 wheel drive truck.

Steve

[68 TWind]

Rodney,
I'm like Vernon and not convinced it is a u-joint. That said, the easy checks are u-joints and engine mounts. I had a bad vibration in a Suburban one and the center carrier bearing on the drive shaft was bad. Took me a while to figure that one out. Might be someting else to check.

Good luck.

Bruce

[Boondocker]

Does anyone have suggestions for finding help in Albuquerque? I want to get this fixed but I cant afford to just throw money at this one thing at a time and hope something fixes the problem. What garages are the safest bet?

[nmbosa]

Ditto what War Eagle said. Ford Truck Enthusiasts site can be very helfpul, and if one of those guys are near you, they might even come over and help you with it.

[TomW]

Originally Posted by Boondocker

How does one [check motor mounts]?

Go down to the local auto-chain-parts store with your camera, and ask to see a set of new motor mounts. Make note of how the upper & lower plates are segregated by the big piece of rubber. Then locate your truck's motor mounts, and compare them to your pictures.

FWIW, one day, oh let's say 12 years ago, I noticed the sound of an exhaust leak on the Mighty Burb. On the rack at the muffler shop, the RH muffler's inlet pipe was found to be loose. After the pipe was welded, I asked the technician how that might have happened, and he asked me if I had checked my motor mounts lately. Sure enough, the passenger side motor mount was totally smushed. The lack-of-tight-attachment had allowed the motor to twist the pipe out of the muffler.

Oddly, though, I never felt any vibration before replacing the mount nor did I think there was less vibration after the new mount was installed.

Tom