MBNUT1

I am starting to get a grindy / scratchy noise when I push on the throttle at 20 MPH and above. I think that it is driveline related because it doesn't change with engine speed (ie shifting gears doesn't make much difference) but does get louder with more engine torque applied and in fact goes away when I let off of the throttle. I know that my engine mounts are worn. Could this cause something to rub on the driveline. Another possibility is it is in the output part of the transmission. I had the transfer gearbox rebuilt a year ago but that was more speed related and didn't go away with torque.

Another thought is I wonder if an exhaust mount has broken and something is rubbing on the exhaust.

Any of you guys spent enough time underneath an E3504matic to have any ideas?

Arrie

You say 20 mph and above. Sure it doesn’t do it from zero speed up at any speed with torque applied.

If it does see see if you can hear it when reversing. Hard to go 20 mph reversing, that’s why I wonder if you could actually hear it at very low speed too.

If noise exist going forward but not reversing I suspect your transfer case bearing is failing again.

MBNUT1

Arrie,

Thanks for the reply. I drove it over to the indy that repaired the transfer case a year ago tonight. I think as you suggest the noise is there at lower speeds as well as long as I apply sufficient torque. I also suspect you are right about it being the transfer case again though the noise is different this time. It was noisey independent of torque application last time but I have been hearing a very faint high pitched whine similar to a precurser last time it failed. It was fairly quiet at speed as long as I was not applying much load.

We shall see.

Arrie

If you have indy or anybody repairing it ask then to look for a stronger bearing. They probably get the OEM part but many bearings (not all) come with different load ratings. This means that the bearings with all the same physical dimensions can have different number of rollers in them. You need a bearing to physically fit in place with more load bearing capability and I'm guessing the problem is with the axial force rating, not the radial force.

MBNUT1

So got it back without a diagnosis. They heard it during the test drive but couldn't get it to do it on a lift (no load). He wanted to pull the front differential fluid to see if there was metal in it but that meant the work of pulling the axle to refill and didn't think replacing the differential fluid would make the noise go away. He didn't think that it was the transfer gearbox again. Said to keep driving until the noise gets bad enough to make it easier to diagnose.

MBNUT1

FWIW the noise that I was hearing seems to have gone away for the time being. Beginning to wonder if it was a brake issue. The thing I can't figure is how applying load to the drive train would translate to a brake noise.

MBNUT1

Well the noise came back consistently...... I took it to another indy who claimed it was the front differential and since I needed engine mounts anyway and if the diffrential needed to be replaced I would get the mounts done for free, I authorized replacing the differential with a used one. He called me today and said he still hears a noise. I went for a ride and the exact noise that I took it in for is still there.

He now says it is the transfer case which was rebuilt a little over a year ago at another indy who I had look at this noise while it was under the year warranty and wanted to drain the diff fluid. We ran it on the lift today after the test drive and I agree that the differential is quiet and the transfer case is noisey. He claims the old differential was so loud that they couldn't hear the transfer case. Which bothers me because the car it doesn't sound any different to me during the test drive.

He showed me the fluid that they drained from it which had bits of metal in it. But for all I know it if you took every differential with 130K miles it would show the same thing. Obviously I will take it back to the guy who did the transfer case but I will be really surprised if he doesn't try to weasel out of fixing it.

The only good news is the new mounts have made the car really nice other than the driveline noise.

Any advise? I don't know why the customer should have to own the responsibility for a misdiagnosis.

Signed,
Totally Depressed.

Oda112

Bummer. Sounds like they screwed up the bearing job on the t-box. Timken should be the to go on this one. I don't recall the exact OD&ID numbers but they're on the forum somewhere. Maybe the King knows the numbers by heart.

MBNUT1

I will pull out my receipt but I recall them claiming to use a better bearing. I thought they said Timken.

MBNUT1

Ok So I took it back to the guy who did the rebuild of the transfer case and he agrees that it is the transfer case. He has ordered the parts and will rebuild it. I was worried about continuing to drive it with the noise but he reassured me that it would be ok. He said he thinks the issue could be the tolerances associated with the alignment of the bearing race.

Arrie

These bearings are conical bearings designed to carry both axial and radial forces. Misalignment of the bearings can ONLY happen if the bearing clearance is set too loose. This would allow axle to move axially, which means the ends of the shaft move radially in opposite directions and cause misalignment of the shaft.

The noise you hear in this case would be the gear wheel teeth hitting each other with corners of the teeth and this can destroy the gear wheels so your Indy mechanic needs to go back to the gear box school to learn about this fact. You truly can cause much more damage by driving it.

The opposite mistake with these bearings is to set clearance too tight. Too tight setting can destroy the bearings themself that then send pieces of metal around and can really wreck havoc inside the box.

Don’t drive it before fix is my advice.

MBNUT1

Hi Arrie,

Thanks for the response. I have been worrying about the potential damage to the gear teeth as well. I am worried that when they put it back together it is still going to be noisy.
We only have two cars so I don't have a lot of choice but I will drive it minimally.

He claimed that the premature wear was due to the clearances being too tight. He said he learned this from previous rebuild returns. I also brought up the issue of contamination. ( I am an hydraulic system engineer) His response was the same as previously in that the contamination will go to the bottom of of the transfer case (I have been worried that it would find its way back into the transmission and the control body in particular. The 4th to 5th shift has kind of a pause that I don't like.

LILBENZ230

I'm assuming they checked/ruled out/replaced the transmission mount? I had a scratchy noise from the drivetrain on my RWD W203 many years ago that turned out to be a collapsed transmission mount. It was very strange the noise it made and what it turned out to be - so I felt like it was worth mentioning.

MBNUT1

Good question. However the transmission mount was replaced a year ago when they rebuilt the transfer case. Doesn't mean the the new one couldn't be collapse if they used non OEM.

Arrie

Contamination goes in the bottom of the pan but where does it go before it reaches the pan?

if a bearing fails it means the race surfaces flake off. These flakes are very thin surface material flakes and is not the same contamination as what normally is found on the magnets in the pan. These flakes can easily move with oil and with bad luck can end up in a gear mesh between two gear wheels and that is when the real damage can happen.