LSUMatt1514

I first noticed this day before yesterday and it seems to be getting progressively worse. I do not really notice it until I get above 55 mph but at that point, I start to hear a low frequency hum and feel a low frequency vibration. It is really evident driving 75 mph on the interstate. The weird thing is that if I take my foot off of the accelerator, it stops! I talked with the service mananger at Limbaugh Toyota on the way into work tonight, and he said it sounds like a problem with the drive shaft u joints. I have no idea. I've always had vibration that I haven't been able to completely smooth out, but this is totally different. This vibration and the associated hum sound stops when I take my foot off the gas. Any ideas as to what is going on here? If it sounds like a drive shaft u joint issue, how much is that going to set me back? It is really bothering me because it sounds really bad and is very noticeable and I'm afraid that if I don't address it soon, it will lead to further problems. Thanks for your help guys.

Matt

Tacoclimber

In this case, it does sound like a driveshaft issue. I had a similar experience with my 86 Hilux. It was a bad u-joint. I ended up doing my own with the help of a mechanic friend.

LSUMatt1514

U joints look fine and there is no "play" in them whatsoever. I've talked to numerous people at work tonight, and noone can come up with a definitive cause.

One person did suggest the torque converter because he said he had a very similar problem on his Chevy truck about 8-10 years ago (same symptoms and reaction to the accelerator). Keep in mind, my truck has over 160k miles on it. However, it has had regular transmission maintenance (flushes and drains/refills).

One thing worth noting...I have seen a few spots of oil or grease or something in the driveway the past week or so. It's not an oil leak because the spots are scattered around in several areas and only about the size of a quarter. I see no evidence of any oil leaks, so I don't think it's oil. It may be related to this problem, however I see no signs of grease being slung out under the truck or any fluids leaking under the truck. I guess it's going to the dealer on Friday.

LSUMatt1514

I've read that you can't really feel play in the U joints unless the truck is off the ground. Is that true?

Another question I've got is that if the U joints were indeed bad and were the cause, why would it stop when I let off the accelerator? The drive shaft is still turning at that point and it seems like the symptoms would still be there whether the accelerator was pushed in or not.

I'm starting to think that I've got something going on with my exhaust system that is making this noise/hum/drone or whatever you want to call it and the associated vibration. I just had my Dynomax muffler replaced under warranty a few months ago because it had rusted through and was leaking at the inlet pipe. While I was at it, I replaced my resonated exhaust tip as well. I did notice when I got home from work this morning that with the windows down and me revving the engine, the exhaust tone was noticeably different from what it has been. Noticeably different.

I've been fighting the P0420 catalytic converter code for months, and at this point I still don't know if my DUAL cats (yes I'm one of the lucky ones with two) are bad or if it's an O2 sensor, MAF sensor, etc causing this code.

I'm leaning towards something broken loose inside the muffler, and that's what the exhaust shop owner told me this morning. I think I'll stop there before I go to the dealer. I don't know what's up, but something is not right.

seanathan

i had the same prob and mine was a u joint the way i found out was took off the e-brake layed under it and moved it around mine ended up being the rear one by the pumpkin but i was also told it could be like a dent or bend in the drive shaft

terryjmatthew

Matt,
I had a similar problem w/ my 4Runner right after I bought it. Mine turned out to be a bad pinion bearing.

d0ubledown

i recently had that same situation. however, at low speeds from a stop, it squeaked like crazy. it was the u-joint. dealer diagnosed it as a ujoint. brought it to my usual shop to get em to replace it, but they said it had no play and was fine...

took a 1000km road trip to calgary, and on the way there, the drone/hum started. it didnt really go away when i was off the gas, just quieted down some. usually, itll make more of a noise when theres load on the joint. i was pissed that my shop didnt replace it (they said they were trying to save me some money even though i TOLD em to replace it ) anyway, out of town with the kids and i had to take it to the dealership for repair as i wasnt going to drive another 1000km back like that. once they fixed it..no more squeak, hum or drone.

bottom line: if you can replace it yourself, i would. all you need is a vice and some tools + service manual. if not..the dealership charged me about $300CDN. if you take it to a nondealer shop and they have a look at it, they'll probably say it doesnt need replacing. dont listen to em and have em do it regardless. i really wish i had the time to do it myself, i would have saved the grief and inconvenience of having to take it to a shop, twice.

keithguts

I have a 95 runner and it had the same problem. It did turn out to be the u joints. And yes the rig should be off the ground when checking for play. Also push up and down on the shaft as well. Mine had play when it was pushed up and down, and very little play from side to side. After replacing the u joints, it ran a smooth as silk. Never had a problem again.

Finelygotone

Keep in mind too, that a lot of U joint problems cannot be diagnosed unless you pull the d shaft off of the truck....a few bad needles are enough to create a noise but you won't be able to tell unless you can get to each cap and check it for roughness, excessive play, etc.. Most of the u joints I have replaced could not be properly analyzed with the d shaft on the vehicle....

LSUMatt1514

Exactly right. We did not feel any slop in the U joint the other night with the truck on the ground, but as soon as we got it up on the rack.....dear god. The front U joint had a TON of slop in it. Got them both replaced and all is good. Thanks for the help guys. I was starting to get really worried because I knew if I didn't do something that the hum, whatever it was, was going to lead to further problems and it could have. Had I ignored it, it could have wallowed out the driveshaft to a point that a new U joint would have done no good and I would have had to put a new drive shaft on. Crisis averted and problem solved. Thanks guys!!!

Matt

tgillespie

Had the same problem on my 94. Insane shake. After putting it up, discovered exactly what you did.