91 f350 7.3 idi turbo crew cab - new owner - odd vibration when driving

[davlun]

Hello,

New owner in the idi engine/truck and could use some help from some experienced wrenches on the idi:

The Bad:
Hard to describe, but if you imagine that point in time right between accelerating and decelerating, coasting or floating right between those points in time, there is a distinct vibration that is easily felt throughout the truck. It starts about 58 mph and above. If you take your foot of the gas, it goes away, it you give it some gas, enough to start increasing your speed, it goes away. If you try to just run along keeping it at 60 by up and down on the pedal, you get the vibration.

A garage mechanic was kind enough to put a tester on it, it showed an issue with map or barro sensor and he said i needed to it fixed, but not immediate, I could continue drive home. I had stopped because the engine light had come on during a grade, but it turned off shortly after I noticed it. As he was finished doing the test, he cleared the codes. His scanner may showed an issue with the timing?? but not sure as he had cleared off before I could see.

The good I am told about the engine
- rebuilt engine and trans a couple years ago, about 40k average on each
- new tires, new ball joints and couple other things in the front end
- new batteries, alternator, radiator
- banks powerpak, factory installed
- mechanic said it was one of the nicer ones he had seen lately mechanically with the exception of brakes and exhaust

Some observations.
- lots of rattles and such in general on the interior
- there is a bit of clunking up in the engine are, drivers side, when entering parking lots, where there is a lot of angle changes in the ground, sound like something loose
- windshield is cracked horizontally, there is a rock chip visible, but i wondered if the car was flexing and that causes the crack to go across the window

Thanks to those who made it this far, did not know what was relevant so wanted to list a good summary.

David

 

[79jasper]

That "mechanic" was bullchittin you.
Only codes it can put out are for the transmission.
Also won't show anything about timing.
Check your u joints.
I bet the engine light came on because it got a little too hot, or bad temp sensor.
I bet you can solve the clunk by tightening the fender bolts. (Unless the ball joints aren't actually new)

Sent from my SM-G900R4 using Tapatalk

 

[davlun]

Interesting...

He had a scan tool plugged in to the port in the front, had to go get the right plug from the back of the garage.. ran tests. turn key on, off, start, etc... Maybe it was the wrong test.

As to your suggesting, I crawled under ujoints do not seem loose... but it is dark here right now and I am learning how to be my own mechanic. How should I evaluate them?

Thanks!

David

 

[davlun]

Almost forgot, I will check the fender. If that is the issues, should it wiggle if I try to give it a shake? I had read there was a stiffener, aluminum, bolted in there somewhere. I was thinking maybe as the car really was flexing when going through the stress of street, gutter, curb, ramp, incline in parking lot. I was worried that the windshield had cracked because it was flexing.

 

[Sycostang67]

There is an OBD port on these trucks, but there is nothing electrical on the motor that the scan tool would tell you about. There are only three sensors on these motors that I can think of, oil, water temp, and water in fuel. It does sound like you might have a drive shaft vibration though.

 

[davlun]

Thanks for the info, the 'mechanic' was the 24/7 type off the interstate so little chance I would have gone there anyway. I have a binder full of receipts, couple diff owners have kept it up. I do not see any notes on u-joints in the receipts, so it may have been a long time since they were changed.

I did see that the drive shaft was either rebalanced or purchased new from a third party, found a sticker on it that is definitely not ford part. It has seen some years judging by appearance, but that can be deceiving.

With the 7.3, do I need to get any special u-joints?

 

[OLDBULL8]

Just remember, these trucks (91) are 23 yrs. old and there are/is damn few mechanics anywhere that know about these diesel engines or even the mechanics of these trucks. If he is 60 yrs. old or more, he may know something.

There is no good manuals for these trucks, except the original Ford manuals. Chilton is useless, Haynes has a diesel Tech manual #10330 has some info, but only about 40 pages.

If the drive shaft has a center support, the bearing may be shot, check the U-joints. Front axle or a TTB, ball joints, king pins, sway bar bushings, wheel spindle bearings, spring bushings, all that stuff can give you the noise your hearing.

Put the truck info in your sig including the type of tranny, auto or manual.

 

[GOOSE]

I have nearly the same truck and the drivetrain is getting a little "loose" if you would say. I would look at the traans/engine mounts just for general preventative maintenance. The U-joints and carrier bearing are a prime suspect as is the rear pinion yoke. My U-joint has side to side play within the yoke telling me that the yoke needs replacing. I am going to look for a newer axle, obs era, they have a lengthened pinion yoke area, Fords upgrade to this common problem.

The guys are right, scanning this truck will get you very little info. Mine doesn't even have a port as it is a 5 speed. Everything on the engine is mechanical. You need a timing meter to time the pump, the injectors need to be removed to be pop tested and matched. The genuine Ford manual and the pages on this site are your best source for information with these old rigs. Good luck and keep us posted.

 

[rattleonby]

Sounds like ya got a nice truck! Now as for your issues....

A: The clunking/snapping/binding sound you hear (if given your front end is tight) on severe angle dips and entrances into driveways and such is relatively normal.
The suspects are usually the radius arm bushings IF your truck is a 4X2 which i dont know. If its a 4X4 i would check your leaf spring bushings in the front.

B: The other suspect noise is usually the front crossmember under the engine binding and flexing between the framerails which is usually remedied by welding the crossmember to the framerails which as we all know is a royal P.I.T.A! Personally i live with the noise because im not picky with a 92'.

C: The driveline vibration your experinencing is more than likely your driveshaft vibrating at a certain speed just like mine does. Now this can still be an issue even IF your u-joints and carrier bearing/bushing are all tight and/or replaced. Youll just have to get picky with shimming the carrier bearing housing until the vibration is much less or if not totally resolved. My CCDRW truck has the driveline vibration from about 35-45 only. Its really all about what you can live with!

Hope i helped shed some insight....merlin

 

[davlun]

So, an update.

First, I gave up trying to diagnose the u joints. I did not see any play but I am definitely learning and youtube only gets you so far. Pep boys gave me a free inspection, they said i have a bad u joint, but also transmission mount, driver rear axle seal, rear wheel cylinders and a leak in the trans that caused the mount to go bad but trans feels good to me...

I had them put the wheels back on, and now the truck has a NEW rattle/vibration that shows itself even in neutral as long as the revs get up, wonder if they did something... and if so, how would I tell.

Anyway, going to get brakes and trans mount done first, then see where we sit.

Thanks for the advice so far, I really appreciate it.

 

[davlun]

changing priorities for just a bit. brake issue seems to not be a leaky wheel cylinder but more serious and shop advised me not to drive it.

will pause here on this one and open a thread on that separately.

David

 

[Agnem]

Rear axle seal leaks are not uncommon on these, and Ford has an upgraded bearing design with an additional oil slinger. They won't know this, and so their advice may not be very good either. Your shoes are probably saturated with oil, hence their recommendation for you to not drive it. You have a laundry list of things going, so it would be best to conquer and divide. Pick what problem you want to fix first and start with that. You should also consider just rebuilding the driveline rather then diagnosing it. It is cheap, easy and won't bother you again for many many years. Locate your local Dana/Spicer authorized shop who builds driveshafts from scratch, and get all your parts from them. If you can't find one locally, I would recommend Buds Spring shop in Lancaster PA.

 

[davlun]

Thanks for the advice, understood and received.

I have decided on all things safety first, working on getting brakes solved now. It is a bit disappointing on a new truck, but will get it going.

 

[79jasper]

On the rear axle seals, Timken and Scott seals have a better design.
It's a two piece "bearing seal."
The inner part stays stationary on the hub shaft vs spinning on the hub shaft.

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[davlun]

On the rear axle seals, Timken and Scott seals have a better design.
It's a two piece "bearing seal."
The inner part stays stationary on the hub shaft vs spinning on the hub shaft.

Thanks! I was reading in the forums somewhere that there was a better design with an improved oil thrower, wonder if this is what they were referring to.