low speed vibration

Update - I told the shop today of the worse vibration since their driveline work and the (probably longtime) symptom I found wiggling the left front tire, and they checked out both front wheel bearings, retightened them. I jacked up the same tire when I got home and I'm still getting the slight clunk as I wiggled the tire from top to bottom. I'm dismayed they didn't test that.

They said engine mounts are fine, no undue rotation of the engine when shifting.

I figured out this evening I'm getting constant vibration in park and neutral. With my foot on the brake I shifted several times between gears. I get 1-2 seconds post-shift vibration going into R or D, after which the it feels smooth until I shift away again. Same behavior when I go to a flat area where it won't roll and leave my foot off the brake while shifting. The post-shift vibration seems to coincide with the brief RPM raise while shifting, but when I press the gas pedal to raise the RPMs while moving in drive or reverse it's fine, but there is the same kind of vibration symptom sometimes when slowly crawling before and after a stop while driving. The shifting is not delayed, it's followed by the vibration. Shifting between 1, 2, and D has no issues. What could cause this?

We agreed I'd come back in a week or two if it wasn't better, and they said the transmission mount needed time to wear in because it's new.

 

mechanic is full of shit

 

Take it to a better mechanic. These are very simple trucks and any decent mechanic would sort this out quickly.

 

I'm thinking I should do that. I gave them two chances and things are only getting worse.

I also had them change the brake fluid yesterday, because the copper corrosion level with this test strip was 300. Afterwards I tested the new fluid and it was 300 again. Is there such a thing as brake fluid that makes this test read wrong?

$16 Phoenix Systems 8006-B Double-Ended Brake Fluid + Coolant Test Strips (15 foil wrapped test strips), 1 Pack

https://www.amazon.com/gp/product/B0753MZT7P

 

i doubt they ever changed it, again Indont trust mechanics ive been burned by all of em, I do my own work

 

Totally makes sense, but I just want this to be fixed and don't want to spend time thinking or working on this. I have other things to do. I guess I'm familiar with other industries where virtually every professional you can find is incompetent or a ripoff, and everyone just keeps paying them and suffering for it.

 

You can find good shops. They are usually specialists and won't be cheap but if you want someone to do it for you it is best to pay once and cry once.

 

I work in tech but I have been a mechanic for over 40 years. I have owned dozens of interesting cars and have never used a mechanic in my life*. Just flush the fluid and skip these tests. The test cost as much as a couple flushes. Brake fluid sucks moisture out of the air so it has a finite life. Put the cost of that test towards a Motive power bleeder and just push the old junk out every year or two.

* Point being that I know a thing or two and it's silly to test it. Replace it every couple years.

 

I already have the test strips. I watched some youtube videos on changing the brake fluid, and they involve buy extra tools, DIY homemade tools using nothing I have, and procedures with disassembling the brakes that I'm not comfortable doing and really don't want to spend that kind of time at it. My little one car garage is loaded up with hundreds of dollars of mechanic tools I've had to buy, and I'd really like to use my garage storage for other stuff too. I just want it done and want to be able to tell it's been done. That's why I got the pack of test strips. Is there a better way to confirm it?

I'm getting frustrated because I've been dealing with this vibration since September, and now it's worse than ever. The brake fluid that didn't get changed is a cherry on top, along with the loose wheel they said they fixed but obviously didn't even try to wiggle. It's like I'm spending all my time with mechanics who don't fix anything, don't do what I ask, pretend like it drives great, and sell me more parts and labor that just create more problems.

 

I feel your pain and lord knows I have heard it hundreds of times over the years. Its a damn shame. If you were local to me I would just tell you to bring it over and we could diagnose it in an hour. Are you in Oregon by chance?

 

Nope, bay area CA unfortunately. I do suspect that local mechanics in more rural areas, if they have the skills and equipment, are much better to go to for older vehicles like this because they have way less overhead costs to meet and can take their time.

 

To me the issue with wrenching on 20+ year old vehicles is the attention to detail as lots of 'while you are in there' stuff comes up all the time. Even if it is just cleaning and inspecting, it takes time and attention to properly service older vehicles especially if they have neglected maintenance. Unfortunately most mechanics don't have the time to watch the details as they are under pressure to just spend X time on X job and older vehicles need a shop that will spend that extra time without killing your bank account. I hear rumor of such shops existing but I certainly cant direct you to any.

 

I totally see that. The oil drain plug plastic gasket fell apart in my fingers like it was 10 years old or even 1996 original and every shop decided to reuse it. A stripped transmission pan bolt. Throttle cables that were too loose and the nuts not even hand tightened. The whole air intake system from the filter box to the throttle body layered with dirt and carbon. It's like not a single mechanic ever tried cleaning anything or replacing small pieces.

 

Update - I take the truck to the largest shop in my city in a shopping center and agreed to a $400 estimate just to diagnose. I tell them the other shop did something to cause these vibrations while doing the driveline work. After a day they say they can't find any of the vibration problems I describe, if anything it's just age, the truck runs great for its age, and if there's any vibration there's not enough to diagnose.

I asked if I can come and show them, because the feeling is obvious, it's a new problem from the driveline work or whatever the other shop screwed with, and it feels really bad to me. I probably should have showed them when dropping it off so we're on the same page, but anyway they're insisting there's no problem. They said a driveline issue would be low speed vibration, and I said that's exactly what I'm feeling. I interpret this as meaning they can't figure out the cause and to cover their ass are backtracking and pretending there's no problem.

Do I need to take it to a dealer to get someone competent or honest, or are they no better? I don't need someone both competent and honest, just one of the two would be amazing. I don't know whether it's driveline or the first shop screwed something else up, I'm depending on a pro to figure that out and fix it, not have to keep explaining this crap to each one like I should have to know anything to change gears, point to the steering wheel shaking, and tell them to fix it.

In this condition I don't even want to drive it and certainly nobody would buy it. I would have to take it to a junkyard or whatever.

 

"96 3.4L V6 automatic 2wd, 300k miles"
300K on the transmission so look into the rear output shaft/bearing assembly. If there is a support output bearing and shaft wearing within the transmission then this could be your cause of vibration.

You mentioned inspecting the driveline so make sure that these are inspected...
1. Rear axle bearings.
2. The rear differential pinion gear.
3. The driveshaft carrier bearing.

300,000 is quite a bit of miles.

 

Ok, I might see if I can have someone check out the rear axle area really good. Could possibly be causing the first vibration (20mph), because that's mostly when going uphill where I think more stress would be on the rear. But the latest vibration after shifting gears I feel in the steering wheel when parked, so I feel like that's not in the rear. I just don't understand why it's so hard to have one mechanic shift gears while the other one is underneath feeling where it's coming from.

Driveshaft carrier bearing I've been pointed to by a friend despite the first shop saying it's ok, so that's still on the list and I'll likely try it regardless at whatever third shop I go to. The transmission rear output area sounds like a strong candidate too. The current shop still has the truck and is looking at the EGR system today. There's an air blockage I know of, but the timing is such that that's not it, it's the drivetrain. I feel like i'm in clown world, telling the shop that the drivetrain is the only possible culprit of the second vibration because that's what the first shop touched, and they insist on looking at the EGR instead.

 

Troubleshooting a vibration is a process of elimination.
If you are parked and the vibration is coming from the steering wheel I would take a close look at the engine.
1.Engine and transmission mounts.
2. Misfiring, even if there is no DTCs.

 

Any way to find a misfire without a trouble code?

First shop says engine mounts should be fine because the engine doesn't rotate when shifting gears, but I'm willing to have a shop throw mounts at it because they're so old.

First shop also changed the transmission mount, inspected it again the next day. But who knows.

I'm at the point where I need to find a shop where I can say, check every part in these 10 areas thoroughly, and I mean thoroughly, I don't care how many labor hours it takes over how many days or weeks, and I shouldn't have to research this and make a list because I'm not the mechanic, but apparently it's necessary so here's the list, make sure it's all 100% good, don't throw parts at it just to say you did something, just take the time to figure it out and fix whatever is causing the problem.

But I don't know, maybe they simply aren't making enough on labor charges and they have to sell me parts to make enough money off me or they'd rather deal with another customer they can fleece for $1500 in parts on top of the labor?

 

Remember that you can take your time in finding out what is wrong with your truck.

 

when was upper/lower ball joint replaced....
.....these are a weak spot on this......