I recently noticed a clunk every now and then coming from driver side front while driving the 85 300D.

Today, decided to take a look. Jacked her up and first thing I did was take off front driver wheel. I noticed it was hard to rotate. Pass side spins easily. Rotor surface shows some marks that might indicate locking up.

Clamped brake line closed and opened bleeder to release pressure.
Pads are hardly worn and so far I have not been able to push pistons back. Will remove pins and have another try after a coffee!

May have to get caliper rebuilt, but first step will be to remove and see if there is any apparent problem. Maybe I can get away with cleaning caliper up just replacing seal?

The front calipers were rebuilt in 2014. This one developed a leak after a few months, was repaired and has worked since then. Here is the original thread: Ontario Canada Caliper rebuild

A source for a new or rebuilt ATE in Canada would be of interest!

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

After second look, I decided that I would first remove the pins and pads. Clean them up and lube everything and then see if pads will retract properly.

I was able to push the pads back, but because they have so little wear, they didn't move much. I seem to recall there being two pad thicknesses available. If so, these are the thick ones!

This might not be the cause of the clunking, but needs fixing regardless.

One thing I learned, was that even although our old cars don't get driven many miles, corrosion and dirt don't slow down. I need to check brakes on all three older cars and clean and lube the brake sliding surfaces. Also need to bleed and flush.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

I would think if the pistons and caliper bore are in good condition there would be no reason a seal replacement will not do? Hooefully that solves your problem.

Do check your rubber brake lines too, I am waiting on parts to replace mine as they are starting to dry rot with age.

If you are unable to fit the new pads in , then the piston is not fully retracted inthe caliper. I use a large G clamp to retract the pistons on my calipers .Or a piece of soft wood .Mind you dont damage the rubber piston covers . The pins that go through the pads need a good clean ,,and polish, then a dab of copper grease, so the pads can slide along them before pushing them in place to hold the pads .The caliper seats that the disc pads rub on at the top , and the bottom of the caliper will need cleaning out of old rust ,follow up with a dab of copper grease top and botton on the caliper. Do unscrew the cap on the brake fluid container, so the when the pads are pushed in to place the fluid displacement will go back in to the container .Put old dusters under the fill tank to catch any displaced oil that may overflow .

That was not the problem. The pads have been in for a while but are hardly worn.

After removing the pins and the pads, it was clear there had been quite a lot of heat. Didn't have to move the pistons much to get the pads out, even although pistons were then fully in. Rotors are also hardly worn so no edge at the rim. Lot's of crud.

After removing the pads, I replaced them with plastic spacers about 3/8" thick, then applied the brakes. The outer piston moved in and clamped the plastic, but the inner piston didn't budge. It seems to be stuck.

I think I will buy a set of reman calipers plus new pads and hoses. New calipers can be had in USA for under $200 right now. Remans are cheap in USA, but not that cheap once the core charge is added (which is difficult for us in Canada to recover.)

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

likely the upper and/or lower ball joints.

Hard to check visually, but they "look" OK. The brake problem is real and has to be fixed first anyway.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

OK, I attended to the front left brake issue. No binding now.

But I still get the clunking. There is a stretch of road nearby where the clunk is very repeatable as car goes over relatively small bumps.

DanHough could very well be right that it is ball joints. Or at least suspension related. Visually, I see nothing wrong, but how do I do a meaningful check?

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

jack the car up so that the suspension hangs, using jack stands for safety. if they are really bad, just reach in behind the tire, turning the wheel to give you more room, and grab the verticle of the spindle arm just below the upper ball joint and give it a shake. if there's any movement, it's bad. really bad.



now take some blocks of wood and stack up under the tire leaving about a 1" gap to the tire. take a crow bar, put it in the gap and have a helper lever pressure on the tire up and down while you look at both the lower and upper ball joints. if you see any verticle movement at the joint, the joint is bad.


lastly, if the grease boot is ripped on the joint, it is likely bad as the grease washes out and the joint quickly wears.


-dan

Thanks. I was heading for step one when the brake issue sidetracked me. So I just did a visual - Boots are intact, nothing obviously wrong with ball joints, springs intact (they did once shear off!). Nothing I could detect with wheel bearings. Guide rod mount looked OK.

Step 2 may tell me more. We are self-isolating, so only helper is wife! May have to go solo Thinking it could be shocks seeing it only clunks when going over ruts in road. Although, come to think of it, it also clunks when making 90deg turn into our driveway.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Clunk still there. If I push down hard on front of driver side fender, I get the clunk, and this repeatable.
My local garage will put it up on hoist on Monday. They dont know these cars, but do have a front end/alignment shop. Will see how this goes! Part of getting too old to crawl under cars!

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

I too am getting the too old to crawl under cars syndrome. I am going to have to finish up my vacuum engine oil oil extractor pretty soon. I also am finding it takes two days to complete what I could get done in one. All too often.

Could it be a loose nut on the shock?

I did check that. No need to crawl under the car for the top one! Lower end looked OK when I had wheel off to do brakes.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

My Bendix calipers, which were fine when I parked my 300CD (kids happened, nothing mechanical) 6 years earlier, had one seize up when I started driving it again...

Rebuild wasnt a big deal. It is DIY and straightforward, IMO/IME.

But its not clear to me why this would be a clunk. Id think more like a bad ball joint, bad control arm, or similar...

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)