Author Topic: Odd noise under load (Read 5363 times)

passatdiesel · « **on:** November 24, 2008, 05:58:58 pm »

The car is a 93 Jetta TD GL with 360K. I just purchased this car 2 months ago and have been driving it the past month and have been experiencing a noise I can't identify. Some of the details are that the noise only occurs while the engine is under load while accelerating or decellerating while the transmission is engauged. The sound goes away when you maintain a speed or put the clutch in. If I drive the car then put the car in neutral and coast, the sound quits. The inner and outer CV boots are in great shape, no tears or cracks, so I suspect they have been replaced in the past, but am not able to get that theory verified.

I've replaced the front and rear wheel bearings. New brakes all around, lower ball joints, both tie rod ends, now I have to book the car in for a wheel allignment at some point. The noise has always occured since I bought the car

I have winter tires on the front and thought maybe it was tire noise, so I threw on a summer set, but didn't have any change in sound. I've been trying to read other posts on various forums, so my next step is to replace the throwout bearing since it's cheap, but I don't see how that could be the problem. Unless there are any other idea's, I'm planning on inspecting the transmission when I do the bearing and clutch cable.

I've replaced the transmission fluid with redline MTL when I first bought the car, and I drained out as much oil as I added, so I don't see fluid neglect as being part of the problem.
I have a new manual clutch cable to replace the self adjusting cable, but I don't find the clutch is slipping under hard accel. Even dropping the clutch in first, the clutch grabs well so I can only assume the clutch is in good shape.

I'm located in Sherwood park, if anyone would care to come and drive the car to get a better idea to the problem, what would be appricated.

Looking forward to the positive posts.

zukgod1 · « **Reply #1 on:** November 24, 2008, 06:11:32 pm »

Sounds like bearings in the trans to me with the limited info provided.

Looks like you have replaced everything that is the normal cause for noise so the trans bearing would be the next logical option.

Does it shift ok? Doesn't bind or anything?

Is it noisier in any one gear?

passatdiesel · « **Reply #2 on:** November 24, 2008, 06:18:12 pm »

4th gear seems to be louder then 5th, but only marginal. Shifts great, no grinding or binding. I haven't checked my manual, but what is required in changing the bearings in the tranny? Are they press in bearings?

passatdiesel · « **Reply #3 on:** November 25, 2008, 07:24:22 pm »

replaced the clutch cable tonight, and had no change on the noise. Hopefully my order will come in tonight and I can start on the TO Bearing

zukgod1 · « **Reply #4 on:** November 25, 2008, 07:46:57 pm »

Just an FYI but throwout bearing only make noise when the clutch is pressed and I have never seen a bad one.

I'm going to start the bidding with Output shaft bearings..

passatdiesel · « **Reply #5 on:** November 26, 2008, 05:12:39 am »

What is involved in replacing the output shaft bearing? Is it a total teardown of the transmission. I can't seem to find any relevent info doing a search.

zukgod1 · « **Reply #6 on:** November 26, 2008, 07:27:24 am »

Save this in your bookmarks.

http://www.brokevw.com/

Everything you ever wanted to know is probably there.

Choppercat · « **Reply #7 on:** November 26, 2008, 11:39:44 am »

How about engine mounts? When the engine is under load, some metal to metal contact can happen if the rubbers are worn-out or broken. I would try to wiggle the engine and see if you get any kind of such sound.

zukgod1 · « **Reply #8 on:** November 26, 2008, 12:43:30 pm »

That is a REALLY good idea right there.

However, bad motor mounts usually will come and go when on/off the gas where as a bad output bearing will be there pretty much anytime.

I was going to suggest to th OP that he just find a salvage yard trans if that's a possibility for him.

Here at the local PnP we can get a trans for $75.00 and I don't think you can tear one apart for less than that.
Get some new seals before you install it and run that suka!

burn_your_money · « **Reply #9 on:** November 26, 2008, 05:30:14 pm »

My car does the exact same thing. I've decided that it is the tranny bearings. I plan to just keep driving it until it explodes

passatdiesel · « **Reply #10 on:** November 26, 2008, 07:02:23 pm »

I've checked the motormounts and they seem to be in good condition, some movement when you wiggle the motor but it's acceptable. After driving it today, I find that the pitch of the hum changes depending on rpm and what gear I'm in. If it was the output bearings, wouldn't the sound increase in pitch the faster I go? After each shift the sound decreases and slowly increases again, which would lead me to believe it would be an input bearing perhaps, matching the RPM in sound, and not the speed of the car. Just a thought though. I like that earlier post of drive it till she falls apart and replace what I need. I'll keep my eye on it, and if the sound gets worse, might be handy to have a spare tranny on the shelf if I can get one that cheap.

Thanks for all the advice.

passatdiesel · « **Reply #11 on:** November 29, 2008, 01:59:50 pm »

read this on vwvortex, thought it would be relevent, so incase anyone else is having similar issues, this is what I've come across

The TO bearing would make noise with the clutch pedal depressed, it would be under load then.
The bearing isn't be used when the pedal is not depressed.
I assume you are rolling when you press the pedal and the noise stops.

The car is moving, so the diff and output shaft are spinning, clutch in or out, and the noise comes and goes, so it wouldn't be those.

The thing in the trans that stops spinning when you press the clutch pedal is the input shaft.

It sounds like you have a noisy input shaft bearing, there is a large ball bearing on the shaft near 5th gear at the drivers side, and there is a small roller bearing at the other end of the shaft, just behind the input shaft seal.

If it'll make the noise in neutral, with the car sitting in the driveway, listen to the trans with a screwdirver (handle against your ear, tip on the trans casing) in different spots at each end, and see if you can tell which end is louder. Have someone operate the clutch to start and stop the input shaft so you can listen for the change.