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PLDodd · 06-14-2010, 10:46 AM

The tip-off on engine mounts, like TomW's 'burb was the exhaust noise, not vibration. Broken engine mount will not make the steering shake uncontrollably, steering linkage, gearbox, etc.will. In the VA state inspection procedure we have to inspect all mounts (including transmission) If we find one broken, it's usually noticed by a thump or clunk noise or sensation when in gear & accelerating. Most folks don't even know they have a broken mount when they do!

bobfowler · 06-14-2010, 10:54 AM

I had a busted MM on a 1972 Ford full sized wagon (351 W and auto trans). Whenever I hit the gas, the left side of the engine would come up real hard and knock the car out of gear!

**GCinSC2** · 06-15-2010, 05:59 PM

Boondocker,

Do you know what flywheel and clutch is in your truck right now?

Your 1997 7.3L with a manual transmission was built by Ford with a Dual Mass Flywheel, DMF. Your original or service DMF has about 120 components in it including a double row ball bearing to seperate the secondary flywheel from the primary flywheel. If this bearing is worn and allowing the secondary F/W to orbit rather than stay concentric, it is a huge source of potential imbalance to an engine and the coming and going matches up fairly well.

If you would like to determine which F/W you have, remove the dust cover under the F/W it bolts to the transmission with about 4 small bolts. If you see springs in the engine side of the F/W, it is a DMF. The solid F/W is just that, solid.

If you have been converted to a solid flywheel optional aftermarket system, none of this applies, those flywheels are one piece cast iron.

If DMF equipped, start engine, select neutral, engage clutch (pedal up) increase engine rpm, feel for vibration(s).

I have also learned a lot about my trucks with an infrared non contact thermometer. By shooting the exhaust manifold right at the cylinder head connection you can see temp differences that might point to miss firing cylinders.

I think I can add to this list, but consider trying this first.

Good luck.

Boondocker · 07-17-2010, 02:34 PM

I took the truck into the ford dealer to see what they thought. They said I needed a new fly wheel and clutch. This seemed suspicious to me since I had replaced the clutch a couple years ago and didnt really think that was it. So being cautious, I asked around about the ford dealer- nobody had good things to say. I did find a local diesel shop with good recommendations. Their verdict: bad hubs and you are lucky the wheel didn't fall off.

While replacing the hubs they found the ball joints were bad and since the tires were pretty much buggered up they replaced the front tires as well. I sure hope that gets it because I cant afford to rebuild the truck one piece at a time.

MrBeast · 07-18-2010, 01:30 AM

Quote:

Originally Posted by Boondocker

I took the truck into the ford dealer to see what they thought. They said I needed a new fly wheel and clutch. This seemed suspicious to me since I had replaced the clutch a couple years ago and didnt really think that was it. So being cautious, I asked around about the ford dealer- nobody had good things to say. I did find a local diesel shop with good recommendations. Their verdict: bad hubs and you are lucky the wheel didn't fall off.

While replacing the hubs they found the ball joints were bad and since the tires were pretty much buggered up they replaced the front tires as well. I sure hope that gets it because I cant afford to rebuild the truck one piece at a time.

The Diagnosis they provided sounds spot on to me, and with 200K on your truck it was due anyways. The symptom you were experinceing is called "Death Wobble" or DW. It occurs when you have slack in your steering components this allows the tires to caster back and forth like a shoping cart with a bad wheel.

In your case if the slack was in the ball joints and hubs (which if it is a 4x4 it would have been kingpins) that will most definately cause DW.

Something you really need to keep in mind with that big 7.3 up in the front end is that motor is heavy, they put it in medium duty trucks as well as your full size ford. Because it is heavy it is very hard on your suspension components. The moral of the story is you should be getting under your truck with a grease gun atleast once a month and in doing so you will be suprized at how much better it treats you.

I own and opperate a towing company, on my wrecker I often have to grease it once every 2 weeks just to keep the truck happy if I am running it hard. It is a dirty job but the pay off is everything works like it is suposed to and im not having to spend 3 hours a side with a 20 lb sledge like many others trying to drive king pins out.

To be honest, I will never take my vehicle to a dealer for anything if I can help it, they charge more than most shops per hour, and they dont always have the best talent working for them because they are trying to charge the most while paying the least, and they enjoy the dealer status and the draw of unknowing customers to thier shop because they are the suposed experts.

You will find though that independant shops tend to be better because when they fix your vehicle thier reputation is on the line. Id rather deal with a shop that has 5-15 employees verses a dealer who has 100 because at a smaller shop people tend to be more accountable for the work they do, at a dealer through the relative obscurity of being part of a crowd people do not carry the same responsibility.

Boondocker · 07-18-2010, 02:49 PM

Ok, the front end work, while admittedly needed did not fix the issue. All was fine until I got to Albuquerque when the shaking set in with a vengeance.

The symptoms:

Severe shaking which is intermittent.
A low grade (barely perceptible but not normal) shake at idle
The shake has a wobbly feel to it.
Pushing in the clutch (going down highway) results in an immediate but short lived worsening of the shake.
- If you then (clutch still down) push down on the accelerator the shaking returns.

Does this sound like the fly wheel or something else? Oh yeah, the drive shaft was checked and the tie rods are supposedly in OK condition

I have to get this thing into a shop tomorrow and hopefully I can get to Phoenix in time on Wed.

Boondocker · 07-18-2010, 07:15 PM

Im wondering if it might be a burnt under valve cover harness, any thoughts?

I do remember when I had it worked on a couple years ago some of the glow plug related wiring had to be reworked- makes me wonder.

MrBeast · 07-18-2010, 10:29 PM

I am going to say your clutch is highly suspect, if your dual mass flywheel is coming apart it will do exactly what you are describing.

Glow plug wiring will only effect starting of the engine when it is cold.

You also may have an injection pump that is about to go out on you. Have you ever changed your pump? Do you notice any excessive smoke when you are in the throttle?

From what you are describing it sounds to me like either the IP or clutch/flywheel are suspect. but it sounds more like something in the clutch department

MrBeast · 07-18-2010, 10:30 PM

I will also mention that my clutch went out a few weeks ago, one thing you will notice is a lot of vibration, and also it will start grinding going into reverse, not always but usually it will. Mine did that before it finally let go.

**GCinSC2** · 07-19-2010, 06:05 AM

I don't know if you determined if you have a DMF or not, easy to do. Slide under truck remove sheet metal cover under flywheel, look for springs. Springs=DMF. If you see a solid cast iron F/W when you pull the cover, then all of this is for the next guy, not you.

If the vibration is coming from your Dual Mass Flywheel (DMF) you should be able to diagnosis the problem a bit further.

Engine running, parking brake applied, slowly bring up the RPM, feel for vibration. Repeat with different RPM ramp up, feel for vibration. You can also try pushing the clutch pedal (in neutral) at variour RPM ranges to see if it affects the vibration.

This is only looking at the engine and DMF/Clutch as the source of vibration as you are always in N the drive train except for the trans input shaft is out of play, nothing is turning.

If the ball bearing that seperates the Secondary F/W from the Primary section of the F/W has failed then you have a 60+ Lb cast iron element that is not always concentric to the crankshaft = vibration. The erratic occourance may be due to the ball bearings moving around inside the races and the 60Lb assy is floating. Releasing the clutch (pedal down) allows the system to reposition itself slightly again contributing to the random report.

Let me know if you would like to see a picture of the engine side of a DMF or a shot of it's internals, it has a lot of parts in it.

Good luck.

**GCinSC2** · 07-19-2010, 06:09 AM

To help minimize confusion, the clutch industry uses the word CHATTER or SHUDDER or JUDDER to describe an erratic clutch engagement, for example, standing start select 1st gear clutch pedal coming up, truck starts to shake and movement is a bit uncontrolled. Also in REV but not present in 2-3 3-4 4-5 upshifts. Vibration, think of a tire out of balance, it just shakes and doesn't go away. Chatter is momentary and only during the engagement process.

Boondocker · 07-19-2010, 04:58 PM

Turns out that it was the fly wheel. For reasons that are lost on me, when the clutch was replaced a couple years ago the mechanic left the old dual mass fly wheel in place. I'm guessing there should be bearings all around there and not what I have. They got the new one in today, but I didnt get out of the shop before it turned out that the new throw out bearing was bad. Now we are into tomorrow before I get out.

MrBeast · 07-19-2010, 10:55 PM

I got rid of my DMF for that very reason JUNK!

**GCinSC2** · 07-20-2010, 06:01 AM

Boondocker,

Yup, that's the red X alright.

The DMF has a unique talent, it actually adds rotating mass directly to the transmission input shaft. By adding the mass to the pulsating input shaft, the trans is very quiet and all is well. FWIW the Ford DMF also has a torque limiting clutch inside of itself and can at later stages of its service life or at times when a video camera should be running slip internally and mimic a slipping clutch.

Release bearing noises, CAUTION. Identifying the exact cause of the noise needs carefull diagnostics to avoid un-necessary R&R.

Do you know what clutch type was re-installed? back to DMF or a solid flywheel conversion?

BTW, DMF's for Ford 7.3L's have been discontinued by their mfgr. for Ford.

If you had a solid f/w conversion installed, they can allow a bit more noise to be created in the trans than the properly functioning DMF did.

Can the noise be controlled from inside the cab, pedal up, down, in gear in N etc. important because lots of techs assume it's always the throw out bearing.

3 distinct sources of noise.
1. Throw out bearing always turning, always in cotact with the clutch, NO FREEPLAY anymore.
2. Pilot bearing in F/W. Active when engine is running, clutch released (pedal down) and trans in gear. Think waiting at a stoplight.
3. Transmission. Can be isolated from discussion by releasing (pedal down)the clutch and selecting a gear, truck stationary. Nothing in trans is moving at that time.

Good luck.

Boondocker · 07-20-2010, 07:39 AM

The new fly wheel is a single piece. The noise was a screech with the truck setting still, in neutral, and controllable by pushing down the clutch peddle.

Boondocker · 07-20-2010, 09:01 AM

It never (expletive deleted) ends! The fly wheel is changed, and they are replacing the steering shaft due to a bad rag joint- add $600. Now they are telling me there is noise from the transmission (standard) although I am probably OK for now.

I have spent a ton of money on this truck in the last week and I have more fears than I did before. I wonder if I should get out now-not that I can buy even if I want to. What else should I be expecting to go on this thing in the near future? I need to find a mechanic who isnt going to take me apart one repair at a time.

**GCinSC2** · 07-20-2010, 11:51 AM

Rodney,

I'm sorry that you are having problems and your shop has found additional problems.

I looked back at my previous reply to your thread and on 6/15 I mentioned the DMF as a source and a quick test to start the diagnosis.

Noises in the release bearing can be challenging to confim, no doubt, but it can be done. The big thing is not to ASSUME it is the release bearing, confirm to the best of your (technicians) ability.

Rodney, yes, replacing the DMF with a solid F/W can increase the noise the transmission makes.

Most guys would be looking back at the older 7.3L's and wishing they had the durability and reliability of those trucks.

Good luck.

Dakota's Dad · 07-20-2010, 02:50 PM

I don't think I would bail on the truck now. Lets see, 200k, and you have now fixed most of what was wrong with it, all wear parts BTW.

My dad told me when I was young.. you can have new and make payments, or old and make repairs. That's life. BTW, the best way to handle the "make repairs" part is get the manual and a tool box. Nothing they have changed or serviced has an expensive special tool involved, but does have a book rate amount of labor involved.

and, while you have spent a "ton" of money this week on it, you didn't (I hope) make a payment on it, and next week it may cost you nothing, heck next month or even next year.

**GCinSC2** · 07-20-2010, 02:59 PM

FWIW,

The pic in post #32, the statement about "bearings all around in there" has sorta puzzled me, but I believe I have it now.

The ball bearings should not be touching each other they are built seperated evenly by a seperator cage. That cage is gone and now all of the ball bearings can migrate where ever they want to, the secondary F/W and clutch are orbiting, not following the centerline of the crank, = vibration.

To our Duramax owners with manual transmissions, you have a varation of the DMF, but not made by the same company and for my Dodge brothers with the new (mid '05 or so) G56 6 speed you have a cousin of the Duramax DMF.

Happy trails.

slowmover · 07-23-2010, 07:00 AM

Stick with it awhile. At some near future point: change all fluids, reline brakes, new shock absorbers. Some interior/exterior detailing. Good tires. Make it desirable. People buy based on images, and there are good resources online about how to photo vehicles.

Save for a 2004.0 305/555 ISB Cummins with a 6-speed behind it (or, 2003). If you can avoid 4WD you'll be miles ahead on money & maintenance. Avoid Ford diesels as there is no upside to owning one on a cents-per-mile basis (from purchase price to mpg to repairs/maintenance). Start reading auto-trader, now, to see values on yours, and what you want to buy.

There are those who will tell you that diesel trucks are all the same. They aren't (wishful thinking). If you can get a pre-emissions Cummins it will still outlast the rest and get better fuel mileage doing it while having cost the least to buy. The single repair mine has needed thru 168,000 miles is new u-joints. Tires & brakes last over 100,000. 23.2 mpg -- all miles -- the past 18,000 (no big trailer towing), with solo highs of 27 hwy (never less than 24), etc, etc. A pickup truck is an expensive vehicle new or used, so I drive for economy at all times, combine trips, and never rag on it. It has to "pay" it's own way.

Do more online research about current problems. Owners forums (once you peel away the kiddie hotrodders) are a great source for sorting the kind of problem you are having. A clean well-documented truck is highly desirable in the used market.

15 years or 250k is enough.

Good luck.

.