My E150 has a 302 and has developed an intermittant vibration that shows up when the van is going uphill and it starts to slow down from the additional load and before it downshifts. After downshifting, the vibration is gone unless we're still climbing when it upshifts.
On flat surfaces there is no vibration and going downhill there is no vibration. The vibration feels like the riders side rear tire out of balance.
Has anyone experienced this? What would be the cure? Or, where should I be looking for the problem?

 

Sounds like a bad U-joint. Could also be bad plug wires.

 

Wouldn't bad plug wires show up more intermittantly than when I'm going uphill.
Also, if it is plug wires, how do they mask themselves when the van downshifts?

 

A plug wire missfire almost always starts out in high gear, torque converter clutch engaged and under load. Either accelerating or climbing a slight grade.

Downshifting to a lower gear lessens the load and therefore the cause of the missfire.

After re-reading your post, because the vibration goes away on the downshift, I garantee its bad plugs and wires. If it was a u-joint, the vibration wouldn't know the difference.

 

Its been a few days have you discovered the problem?
Warn out ring and pinnion gears can also give you a vibration under load.
I also would check the u joints.

Regards,

Jim

 

Can the U-joints be checked just by trying to rock the driveshaft by hand and feel for a klunking feeling?
How would I check for worn pinion gears? The van only has about 135,000 miles on it. Is that enough to wear out pinion gears?
I picked up some new plug wires but didn't get plugs. Do the plugs tend to go away like the wires do? I pulled the plugs and re-gapped them last Summer. Are there any plugs that work better for the 302? It seems like I had some plugs in it that were called truck plugs but when I went to the local car parts store and asked for the same plugs they didn't know what I was asking for. I think the truck plugs are made by Champion. All the carparts store had available were OEM and stock Champion.

 

That's a new one! Look at the old plugs, read brand & numbers.

Note that routing the plug wires on 302 can be critical & that cross firing from errors in routing can cause vibration from misfiring on acceleration. May even sound like valve clatter. Its highly recommended to use FORD Motorcraft wires.

I use platinum plugs b/c they last a long time & its a PITA to replace them. At the high miles between changes, I do not recommend that they be "re-gapped". By that time the porcelain may be contaminated.

Bad U-joints often make a squishing sound rolling at creeping speed. They can lose just 1 of 4 bearings & feel tight in place. Dropping the driveshaft is pretty easy & allows you to flex each joint to feel how smooth it is. Sometimes close examination of the seals (4/joint) will reveal a bad bearing in place.

 

I use motorcraft or autolites in my 5 liter. They seem to work about as well as anything. I always replace the plugs with the wires, seems like the thing to do. They aren't expensive and only the #5 plug is hard to reach. I use a long extension and go in through the inner fender opening.

As noted above, the wire routing on the 5 liter is critical. If you don't route them as specified the wires will crosstalk and cause all kinds of missfires. There is a diagram under the hood, on the radiator core support, next to the driver's side fender. Follow this diagram exactly and use quality wires.

The only reliable means of checking the joints is to pull the shaft and the joints caps. If you can feel looseness by twisting the driveshaft, the joint is way past "bad".

If the ring and pinion was worn enough to cause this kind of vibration (and it surely can) you would be asking about the whine coming from the rear of the van along with the vibration.

"Truck Plugs" sound like somebody's marketing program. Like Quaker States's "Truck and SUV" motor oil.

 

Not that I suspect it b/c of your vibration, but after 135,000 miles has the rear end had it's oil changed? IMO that's the best way to "check for worn pinion gears?". I'd look for any signs of leakage, pull the fill plug to check level, get a look at oil's condition & top off at the least. If its been 50,000 miles I'd change it, pulling the cover allows you to inspect gears & remove any crud at the bottom.

Also inspect the rear tranny mount, check for oil/dirt accumulated on rubber, or torn, or loose bolts. Some vibrations at load hide out here.

 

I did have a couple of catastrophic failures last year. The original coil died and left me stranded about 60 miles from home and the fuel filter was changed out and the mechanic said it was plugged solid. It was the original also.
I have had some work done on the rear wheel bearings where there was an offset bearing installed because of pitting or something on the axle. They told me that the next time I'd ned new axles. I haven't checked the oil level since then to verify the level.

 

You may be in over your head if you think coil & fuel filter replacements are "catastrophic failures".

Never heard of "an offset bearing" they're specified for ID, OD & depth. However "pitting" is often an issue w/seals failing b/c the axle surface they run on has been compromised by corrosion. In that case a thin SS sleeve is usually installed to restore the surface the seal's lip runs on, thus saving the shaft. Note that this "pitting" is usually linked to water getting it. Any chance your van was in high water? Water contaminated diffy oil is bad news.

 

They are common in the industry. They are often called "repair bearings" and fit in the end of the axle but offset slightly from the OE bearing so it runs on a fresh surface of the axle.



He is obviously referring to pitting of the bearing surface on the axle. Pitting is what you see on the bearing surface of the axle degrading from age, wear, overload, lack of lubrication, overheating, etc.... The bearing's rollers and outer races are likely pitted the same way. This is the most common axle bearing failure. Its why they make offset (repair) bearings.

Its not uncommon for a pinion seal leak to allow the fluid level low enough to cause the axle bearings to oil starve and cause this problem. As the axle bearings eat into the surface of the axle, they gain too much clearnance and allows the axles to become slightly offset. This means the axle is no longer centered in the seal and that causes an axle leak. If you have gear oil in the rear brakes, or see gear oil on the back side of the rear tires, this is likely your problem.

 

My understanding is that there is no wear related "bearing surface on the axle" at all. This is a "common" cartridge bearing where outer race presses in & does no rotate & the axle slides in place, inside the bearing & the inner race & axle spin together. All the running surfaces are within the bearing cartridge. Any minor pitting on the axle shaft, inside the depth of the bearing, is of little consequence.

These bearings do not RUN on the "surface of the axle". The outer race stays put in the axle housing & the inner race stays put on the axle shaft. What "runs" are the ***** (or rollers) inside the bearing itself.

Sorry, but "offset" or "repair bearings" were not "common" enough to make it into McMaster-Carr's comprehensive index, a whole column of listings under bearings.

It would be "uncommon" for oil leaking from a rear end to go undetectable. A quick look should confirm if oil leaked or not. Road dirt generally accumulates on the oil leaving telltale deposits. In contrast, when water gets inside, there is no external clue. While losing a spoonful of oil is no big whoop, a spoonful of water getting inside can fester, corroding the ring, pinion & bearings quite easily. Water contamination can also break down the oil.

 

Dude, I owned a driveline and transmission shop for many years. Think whatever you want. I am sure I can't change your mind once you read it on the internet somewhere.

 

Dude, Google "offset bearing" if you think everything revolves around the internet. Thanks for reminding me to avoid any shop that thinks these axle bearings RUN on "the surface of the axle". I owned a nice TV & computer "for many years" that doesn't automatically convey infallibility onto me if I theorize how they work. Your assumptions continue to be wrong. I didn't need to "read it on the internet somewhere" since I've got a few years under my belt too.

I don't even try to change anybody's mind via posting "on the internet somewhere" in FTE's Forums. Merely offered different interpretations & reasons why. Free advice is often worth no more than you paid for it.