240d, 81, manual trans

Yesterday, after about an hour of driving through absolutely obscene heat (100F, 40C) i began hearing rhythmic noises coming from the rear. I pulled off the highway, rhythmic noises stopped, and as I was decelerating, heard several, i guess, bangs? Almost like a backfire, but deeper and not as loud. Stopped the car, had a look underneath, nothing conclusive, bought something to drink and kept driving. After another 30 mins or so, noise resumes -sounds almost like a slipping belt or an unbalanced washing machine.

UPDATE:

Got the beast on jacks and had a better look... right rear axle boot is completely torn. That whole side is wet looking, I suppose from the axle grease spraying outward as the boot tore at speed. So the boot definitely needs replacing.

I put the car back onto the ground and grabbed the axle itself and gave it a shaking -there's lots of play. The other axle has zero play. I have no idea what's normal.

Am I looking at a new boot, a new axle or possible two new axles?

When the noises are happening..
Stop and backup a few yards..
then continue...
see if that affects the situation ...
if it does I suggest you have half shaft problems...

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

That's a tough one as it only seems to occur at highway speeds (on the actual highway).

Not sure about the last time the rear dif oil was changed. Could that be a possible culprit?

Not likely.

Depending on what is available in your area. A used axle with intact boots from the opposite side of a junk car might be your best option. There are cheap aftermarket Chinese aftermarket easily available. I still feel a used original equipment axle sourced from the other side of a junk car is a vastly better option.

This replacement based on the difference in feel from one sides axel to the other you mention. Clicking can sometimes be rectified by a new boot and lubrication. You quoted bangs when slowing down though.

Sounds like a failed axle, but here are links on the topic.

http://www.peachparts.com/shopforum/diy-links-parts-category/142402-driveshaft-axle-wheel-bearing.html

.

__________________
ASE Master Mechanic
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Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
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Technical Quality Auditor.
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1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

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Thanks guys -Fairly certain it's an axle. Sourced a rebuilt part, now to get her assessed.