transmission vibration? Torque Converter shudder? U-Joint? Stumped.

[ght198267]

got a problem im stuck on here. have searched the threads and still couldnt pin point my problem, which is a first! I have viewed these forums many many times as a guest looking for solutions to various problems and yall are spot on. so I thought Id join up and see if yall can give me a hand. Ill try to be as detailed as possible, here goes, first some specs on my truck

1999
explorer xlt
4.0ltr OHV
automatic
4x4
4door
just hit 200,000kms
all replacement parts I use are OEM Spec or above. And there have been many. hahaha. But I love my Explorer none the less.


here's a list of the symptoms and what ive tried to narrow it down, Im thinking its either the Tranny and torque converter are going bad or a U-Joint or BOTH at the same time, not sure tho. Kinda Stumped.

It vibrates when ever i give it any gas in 3rd gear and above, I can floor it in 1st and 2nd without any vibration till I hit 3rd. Feels like an all over vibration but mainly from the floor boards and steering wheel, like going over constant rumble strips. Seems to be the worst in 3rd gear, 4th and 5th aren't as bad but it still shakes consistently when gas pedal is applied. More gas i give it going up hill the stronger it gets. As soon as i release gas pedal all vibrations stop (after a 1-2 sec delay). Until it downshifts while coasting and vibrations come back. Also when coming up to a stop sign, I'll be braking and suddenly it feels like it "lunges" forward for a second accompanied by a metallic smack sound . Going from P To R there is a noticeable clunk noise, and almost like the truck jars. From R to D there's no noise, sometimes very slight jarring. While driving, up shifts are hard and often I can feel it jar into the next gear. O/D light is NOT blinking, and No other idiot lights are on/ no DTC's.

Going down a deserted hwy at 100kmph i put it in Neutral - Vibrations stop
- give it gas up to almost 5,000rpm and vibrations are still gone, coast down to a stop back into drive and its back. - So I don't think it's an engine mount/miss fire ect

The truck doesn't pull to left or right at any speed or while vibrating, so dont think its an alignment/wheel issue. All bearings are tight, suspension is as well. Except for a rear sway bar squeak (I know there's a TSB for that, just haven't gotten to it yet) Just replaced an upper ball joint (after market 2piece) and sway bar link I found had gone bad while greasing everything for the summer.

Sometimes taking off from a stop i do hear a clunk/ or a metallic tap type noise and on down shift but not always.

U-Joints seem ok on a visual inspection (no rust or damage ect), no play in drive shaft (TC to rear differential), the TC to front Differential shaft does turn less than an inch or so but its always been like that since i've had the truck (not sure if its normal tho)

Motor and tranny mounts seem to be ok on a visual.

Fluids through out truck are normal levels.
Dropped Transmission pan today and replaced fluid with new, nothing suspicious in the pan, minimal amount of very fine metallic sand (14,000kms since last fluid swap). Fluid did have a very feint burnt smell.
(when I first bought the truck, I swapped all fluids first thing and found LARGE quantities of fine metal sand in the pan)

Truck seems sluggish and lacking power up hills/merging onto hwy for the past little while.

 

[gmanpaint]

Sounds like the valve body to me. The rumble might be caused by the pulsing fluid pressure. I would take it to a Trans shop for a proper pressure diagnose.

 

[bobflood]

I would not eliminate engine quite so quickly. Could be missing during your Neutral test - but you're not feeling it because the engine is not connected to the drive train at that point. Good luck.

 

[SoNic67]

If in 1st and 2nd, at same rpm and engine load, you have no symptoms, but you have them in 3rd... it's in the transmission.

Don't slap it in N at 100kmph anymore. You need the transmission internal pump to create oil pressure (when output shaft spins so fast) - it is written in user manual too!

 

[ght198267]

sorry for the late reply, and thanks for yalls,
cant really take it to a reputable transmission shop as the closest one is over 2 hours away.

I swapped out both u-joints on the rear drive shaft on a whim and alot of the vibration is gone. on the rear axle one, the inside of 2 of the bearing cups were dry and showed signs of heat damage to the needle bearings, (non grease-able factory originals) they had no decernable movement when i raised the rear wheels off the ground tho. it still vibrates but not nearly as bad, and mainly when hill climbing, or getting up to highway speed. flat road, constant speed, i dont feel too much anymore. So i figure the vibrations are caused by multiple problems, at any rate thats one problem down. i read somewhere about a TSB with the valve body gasket blowing out or contracting? cant find the post tho to re-read it.

oh and the neutral test was suggested by a mechanic friend to rule some other things out and only to do once. hwy speed, N, coast to a stop, then back into drive.

 

[jcevans2]

When my 99 Explorer was given to me, it had some of the same symptoms. It lunged from park to reverse when backing out of a space. It jerked and shuttered at a certain RPM while cruising and seemed to jump in and out of the wrong gear. I told the parents there was something wrong with it. They said they had it checked and were told it was ok (non-professional friends of friends doing the work). Ugh!

I drove it like that for a long time until I could start doing some maintenance on my own. I started with the spark plugs. When I took the old ones out, I found at least two where metal rod was broken and slid out of the center of the ceramic. I say at least two because I broke two other plugs just trying to unscrew them from the engine. Those could have been broken before I touched them. I installed new plugs and the problem went away completely. However, the damaged may have already been done. About a year later, the reverse failed and had to swap the transmission.

 

[drdoom]

I would be looking at torque converter.