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  #1  
Old 09-09-2012, 09:56 AM
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Smile Rear End of car noise comes and goes, Temperature Related

I've read related issues. It was helpful.

This noise only happens after car has been driven lets say an hour or more. Hard to get the noise when car is not up to operating temperature.

Car has to be up to driving temperature !

Noise:

When driving say around 50MPH-60MPH I hear noise, light whining, let's say from the rear area. I'm thinking rear wheel bearing, rear differntial, or the carrier bearing, that I read about, on drive shaft. Need to find it today.

If steering wheel is "absolutely straight", no noise. If I turn steering alittle off center, R or L, I forget which way now, the noise goes away. But when I go other way, again slightly off center, the noise comes back. It isn't a scary noise just a slight noise. Not real alarming to me.

Consistently!

But it only will do it when car is up to driving temperature.

I can't do it when car is COLD. I tried.

When car is nice and HOT, and I go into a HARD left turn in CIRCLES like at 5 MPH, round and round, I hear the noise again, but a little different but very close.

If I go into a hard RIGHT turn at 5 MPH hor so, like in CIRCLES, no noise.

WHEN I TRY TO GET THIS NOISE BACK WHEN CAR IS COLD THE NOISE WILL NOT COME BACK.

Any ideas??

Thanks in advance!

I need to get some Hex Drives to check rear gear oil which I have never changed with 175K miles. Headed to Auto Zone.

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Old 09-09-2012, 10:03 AM
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Does the noise change pitch with speed?

I had a monotone howl (sounded like the death throes of a sick cow) coming from a slightly frozen caliper on the right rear. It would only do it after an hour or so of driving. The pads were worn and had the pistons over-extended. Did a brake job, flushed the fluid and it stopped.

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Old 09-09-2012, 10:21 AM
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Hi,

I had a major rear brake job about 2 years ago with new calipers but you could be right, frozen calipers or one going bad was my 1st guess.

Thinking as u mentioned, or a bad rear wheel bearing, yesterday I did the following:

Jacked up LR corner with Factory Jack. Tire off ground. Started engine put in gear, got odometer up to say 40MPH and I heard the noise once again. Does not sound like a caliper hanging up to me but it was what u call monotone sound, yes.

So at that point in time Im thinking LR wheel bearing. So I get smart and do same with RR tires and get it off ground.,

Start engine, and get up to 40MPH on speedo and the darn sound is still there.

It makes more noise as I let up on gas and does not sound good. So I test dirve it and perfectly quiet.

Is the rear of car supposed to sound like this if U cut back on gas and one rear wheel is spinning free since it is happening with either wheel off ground?

90% of the time the noise comes on strong when U let up on the gas after hitting 40MPH on speedo. Either R or L tires spnning free, identical.

The noise is like what I hear at 50-60MPH on road but really hard to be very exact.

Thanks
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Old 09-09-2012, 10:32 AM
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Do you have a way to raise both sides at the same time (jack stands)? Would be a better/safer way to hear where the noise is coming from and to check the levels. I do not put cars in gear with any of the drive wheels on the ground. Dangerous way to find out the car has a posi rear.

Starting to sound like differential oil starvation. May want to check the oil level. Are there any damp areas on the differential?

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Old 09-09-2012, 10:50 AM
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No damp areas. Yes u are correct safter to get both off ground but I was ready to apply brake. I can get both off ground today and see what I hear. I tried to get fill plug out yesterday but I need to purchase a 14mm hex male. Today will add some penetrating oil after cleaning area of threads. I hope it is just a lil low on lube. Thanks
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Old 09-09-2012, 02:10 PM
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Any chance one of your rear tires is larger than the other? Diameter, I mean.
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Old 09-09-2012, 05:57 PM
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Im guessing axles also ,tell tell sign is if your boots are ripped.It doesnt take long for road dust to start action on the internals and such.Its common after long ranges of driving for the axles to show themselves of their problems.Its weakened condition gives the car a noticable noise on heavy take offs or heavy driving conditions.
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Old 09-10-2012, 06:42 AM
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I make a tool out of a bolt to remove the fill and drain plugs on differential and used a 12" pipe wrench on 2" long bolt shank. Worked great.

I let oil drain into plastic container and checked quantity and looked for metal showing any problems. Not a speck of metal, lube was color between honey and coffee but felt fine. It felt fine. Quantity was 1.2 quarts or there abouts so it wasn't low.

Refilled with 50% GL-5 and 50% Lucas O.S. . Test drove for over an hour and pretty much is very quiet as it was before when car was not making noise.

Inspected booted, OK. Not cracked.

I felt bearings from underneath and bearing housings seem to be about 110 degrees F. Nothing alarming.

Doubt what I did had anything to do with any potential problem but I'm glad I now have fresh lube in differntial.

Thanks for the replies and idea. Right now no noise. Weird bird.
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Old 09-10-2012, 07:28 AM
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I'd say that it's probably an axle. Sounds pretty consistent with what I've experienced with two axles having given up the ghost on mine.
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Old 09-11-2012, 03:26 PM
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Thumbs up

This site is great since U post a noise and it the noiise goes away!

Since I had heard a weird sound with just one rear wheel at a time raised, both, yesterday I raised both at same time.

Perfectly quiet. Maybe the lube needed changing or my hearing is too good. It had 175K on rear lube, so best it got changed.

So I u want to check for a bad Something, best to raise both wheels or you may hear what I heard, that apparently is normal, if only one wheel is raised and u get speedo up to say 40-50 MPH range.
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Old 09-12-2012, 08:27 PM
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Quote:
Originally Posted by LNGfish View Post
This site is great since U post a noise and it the noiise goes away!

Since I had heard a weird sound with just one rear wheel at a time raised, both, yesterday I raised both at same time.

Perfectly quiet. Maybe the lube needed changing or my hearing is too good. It had 175K on rear lube, so best it got changed.

So I u want to check for a bad Something, best to raise both wheels or you may hear what I heard, that apparently is normal, if only one wheel is raised and u get speedo up to say 40-50 MPH range.
Hey LNG.
Long time no hear!
At the risk of being the grim reaper, I thought from your description that you may have a problem with the spider gear in the diff. The new oil being a bit more viscous has probably made it quiet. When you turn one whell more than the other it turns the spider gears. I suspect you have some very minor ware marks on one side of one of them. Nothing to get too concerned about.
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1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
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Old 09-13-2012, 07:51 AM
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Hello Layback,

Yes long time. How's things?

I'm not sure how the spider gear works in differential so I'll go along with what you say on it about it making alittle noise when one tires if stopped and other tire is moving and gas is let up from say 40-50 MPH with one wheel raised.

Since the rear is quiet with both tires up I'm not going to worry about it now especailly with new gear lube in differential.

I used 50% Lucas and 50% GL-5 dyno; so my rear is covered.

I've had good luck with Luca products.

Steve
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Old 09-13-2012, 08:26 AM
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LNG,
Things are not too bad here.
About to get busy.

The spider gears are those 4 little gears inside the carrier part of your diff. in a straight line the dont turn. When 1 wheel goes faster than the other like in a corner, the balance things out.

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I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
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