Trying to work out bearing noise

[XJClassic]

I've been flat-out with work and have not really given the XJ the attention it needs. I thought I had a damaged transfer case so had it overhauled (found bits of metal when I dropped the TC oil).

The bearing noise is still there.

Did a 200km freeway drive yeserday, spent some time trying to work out what the noise is. There are actually 3 noises; the constant grumble/whirring from about 30km/h up in 2WD. Put it in f/time 4WD and mostly under load it seems there is an additional whirring noise, kind-of comes in and out at regular intervals, seems related to road speed.

Then there is a lighter noise that appears when backing off at around 100km/h. It goes away with application of throttle, or with the brakes applied.

The front diff pinion seal is also developing quite a leak. It has been weeping off and on for months, but I degreased it just before the trip. THe leak is a bit worse, because I noticed a drip of oil formed on the base of the diff this morning.

I couldn't see any abnormal wear with the diff cover off, not that I really know how to tell. Spider gears don't seem to have lost their case hardening.

Some of the spider gears seemed to be worn on the edges and had scuff marks on them.

The pinion gear at the back had shiny marks on the front facing, as if it was rubbing up against something in the diff (crown wheel?).

One of the pics shows the oil pan I'd dropped the old oil into. There were small metal bits in the oil as pictured, and in the sun a kind-of metallic sheen to it.

Took it for a drive just now and I think the noise is slightly quieter, but I could be imagining it.

I know nothing about diffs but if anyone can help I'd appreciate it. I don't want to keep going with parts replacement therapy, it's getting too expensive!

BTW, I also took out the front prop shaft earlier in the week, that wasn't it, basic rumble noise just the same.

[awg]

its fairly likely the diff has worn bearings and needs overhauling.

with the cover off, it is possible to mount a dial gauge, and measure the amount the gears move compared to spec

a dial gauge can be bought cheap on ebay, very handy tool

opinions vary on how urgent it is to O/H a noisy diff, but one thing I do know is they never get better, only worse.

[rainman]

In the wheels and tyres section of the fsm there is a whole section on diagnosing different noises, under different conditions. could be worth a read

[Classic Boy]

If I was diagnosing this based on your info i would reckon one or both pinion bearings has gone bad.

[HamishW96]

Agreed, sounds like when my back diff went. I suggest replacing with a good front diff from a wrecker. I got one from jeeepart recyclers and they warrantied the one that I got as it made metal, and sent me a second one. Great guys. $500 for a d35, im sure a d30 would be similar

[XJClassic]

Originally Posted by HamishW96

Agreed, sounds like when my back diff went. I suggest replacing with a good front diff from a wrecker. I got one from jeeepart recyclers and they warrantied the one that I got as it made metal, and sent me a second one. Great guys. $500 for a d35, im sure a d30 would be similar

I've been quoted $750 to rebuild the D30, drive in, drive out. The D35 I had rebuilt in my last XJ was much more expensive, about $1500 incl a new driveshaft. So $500 for a used D35 is not bad at all.

I will either try to replace the pinion bearings myself or get a used D30 if it's more like $300. Or sell the car. I'm not loving this XJ like I did my last one for some reason.

[HamishW96]

Originally Posted by XJClassic

I've been quoted $750 to rebuild the D30, drive in, drive out. The D35 I had rebuilt in my last XJ was much more expensive, about $1500 incl a new driveshaft. So $500 for a used D35 is not bad at all.

I will either try to replace the pinion bearings myself or get a used D30 if it's more like $300. Or sell the car. I'm not loving this XJ like I did my last one for some reason.

That's cheap, $750 for the rebuild is economical in my eyes... Call around and see what people have to offer with warranty. Will be interesting to see what there is around.

If the cars a good one maybe tough it out and let it grow? My XJ was a real grower tbh. Never a nice car but so much character...