I started a thread, it went sideways, so I'm "rebooting" it here:


I had an engine shake, then it morphed into something else for a long time. I have been paying very close attention to everything I feel, and I have isolated 3 sets of problems:

1. I have one cylinder misbehaving, and I think I've isolated it to #2. I was running with AE up and monitoring PERDELs. There's nothing to see once I'm rolling or on the throttle, but a stop at intersections give me a number. Symptom 1 showed up - the odd noise and something akin to a miss, but not as powerful. This is the symptom that drops the right EGT gauge about 25 degrees. If I get on it, I feel no "miss" per se, and no symptoms of anything being odd. I just slowed from 65 MPH to turn left and hung there for a second to get the PERDEL reading. I could feel something like a partial-miss, #2 PERDEL was elevated, and the driver-side EGTs were 50 degrees higher than the passenger side. I'm going to say that's a nozzle issue (poor atomization) or stuck valve - and it's RAISING the driver-side EGTs, not dropping the passenger side. I have the ninth stick at the ready for that one.
2. There is a growl I can feel in my feet and the wheel, but not my butt or back. It's always there (in gear or neutral - speed related), but it sometimes gets stronger or weaker - with weaker sometime being hardly perceptible. With the frequency of the growl, I'm going to say that one is crank speed or driveline speed. It feels like a bad bearing, but all my spinning bearings are new. I get a little confusion with #2 and #3 symptom, but 42 MPH on up is where these problems live, and 62 MPH hits the sweet spot where it's amplified by the truck.
3. There is a front-end oscillation that I can feel in the wheel (tire speed). This one, combined with the #1 problem gave me the impression the engine was shaking the truck. The oscillation is not there at first, it takes about 10 miles of driving before what ever the cause is "warms up". The wheel will shake a little bit, but my feet don't pick it up. After about 30-35 miles, the intensity is high enough for my feet to pick it up, and it's very annoying. Uphill, downhill, neutral, cruise, power - it's there.

I have jumped out of the truck countless times, IR thermometer in hand, to get immediate readings on everything that spins. The brakes look great and even, the transfer case is the same temp as the transmission (about 70-80 degrees above ambient, but no less than 140 degrees at full temp), the pinion bearing is the warmest thing on the differential (about 50 degrees above ambient), the carrier bearing runs about 60-70 degrees above ambient. The front and rear axles are just something like 30 or 40 degrees above ambient. All front U-joint are ambient temperature, and rears are about 20-30 degrees above ambient.

I raised my eyebrow with the carrier bearing. My driveline guy is done with me, he holds the same opinion as some of my esteemed colleagues here - it's in my head. To that, I say I have one mechanic that agrees something sounds and feels odd... and the Ford dealership replaced the torque converter on their warranty dime in the hopes of eliminating the long-run oscillation that they felt on the test drive.

I am putting Stinky on the lift after a long drive, and we're going to find the growler and the shaker... but I own the misser's ***.

 

Here are two replies to the post above:

 

New intel!


The original shake I felt is back - in spades. It is tied to the RPMs and it is a real honest-to-gawd engine shake. I tried different gears, and it is strongest at 1800 RPM and torque converter locked. I watched the dual EGTs and they would be in sync with each other, implying it's not a miss. Couple this with the fact the shake is there when decelerating downhill with no fueling (FIPW at 0.6 ms), and it argues against a miss. I tried 4X4, and there was an obnoxious whine in the front that I never heard before while in 4X4. This gives sgarder's input merit.

 

I'm sure there's nothing new to you here but. . .

Rubber is hard when it's cold and soft when it's warm. That would affect tires, engine mounts, harmonic balancers, etc.

Air expands when it's hot which would affect tires in this case

The expansion/contraction is also true for steel but to a lesser degree. Different metals expand differently meaning a bearing or bolted connection could be tight when cold and change fit in hot conditions. Sealed connections can change state with temp changes as well.

Again, all things you already know, just tossing it out.

 

Engine mounts? Tranny mounts/bolts?

With all the unbolting, bolting, unbolting, prodding, poking etc. that has gone on with this truck, is there something as simple as a loose or stripped bolt causing issues? VC.s are practically on a timer at this point.....lol

 

F350-6 brought up this in another thread. Can it contribute to your findings.

Centramatic Wheel Balancer, Tire Balancers for DFW Trucks

 

I will be looking at the mounts - that is one thing that can be intermittent. I've been monitoring the harmonic balancer, and it never changes - it's doubtful that can be the root cause of something that comes and goes. I'm thinking of checking my compression again, but I need to buy the right tools for this.

I really need to get two of the vibration sources out of there to isolate the engine shake - it confuses me (no big feat there). I think I may have an answer on the valve noise - I'll report on that if it's not another hairless-brained idea.

 

Rich, I will send you my compression test set up to borrow. It has the Snap-On fitting so it doesn't hit the rockers.

 

That is a gracious offer, thank you! I borrowed one once before, but now I don't have that one. I'd like to get one to keep, as this engine ain't gettin' younger. I know I can find it in a search, but I hear there have been new products for adapting to the GPs on our trucks. What is the flavor of the month for a compression checker that doesn't melt Buck$Zookas?

 

I have a brand new Harbor Freight special that is all brand new. Has everything you need. You can give me a dollar for it.

 

Welll... if you bought something you ended up not needing, we can work out a deal where nobody gets hosed. I've done the same thing with hardware off Da Big Stink. We'll PM later when I can focus.

 

The Harbor freight one typically does not include the proper fitting for our trucks. However its very easy to build the proper fitting for our truck, a grease tube and an adapter and your done.

 

Thanks for that, I'll need to get the thread specs.


I did another test - the powerbrake test. The engine is silky smooth under that load at 1800 RPM, as well as a spirited acceleration or more - it's just something about light load or negative load (decelerating).


All engine mount bolts look undisturbed, with some nice corrosion for a neighborhood. I can't see the snubbers with my eyes, I'll need light and a mirror/inspection camera. The transmission mount looks good.

 

Looks like your checkin' em off and zeroing in.

 

The hardest part of this is identifying a moving target. With three problems wandering around in there and one is intermittent - I can't always lock on to a symptom and say "this is part of problem 1".


I have several appointments with different shops next week - they all have lifts and they say they can isolate vibrations/shakes. Stinky has already been in three shops - they can feel and hear the problem, and the dealership swapped the TC under warranty to see if that helped (I had the flex plate replaced while they were in there). The other two shops handed my keys back, no charge, and told me they couldn't figure out what it was.


I really hope I find a snubber totally destroyed in there - that would be so easy and make so much sense.