1984 300DT; it sounds like the front right brake caliper may be dragging. Question, can I take off the right front tire and turn/spin the rotor and listen for the dragging sound? Anything I should look for?

Thank you for any assistance, it is always appreciated.

You should be able to feel the wheel and tell it is heating up more than other wheels. Also one brake pad might be wearing faster.

Lift the wheel off the ground and spin it. If you hear a scraping noise, you have a dragging caliper.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Best system I have found for me. I drive the car for a few miles. Coast to a stop and compare all the wheel temperatures. Reading the temperature near the wheel hubs. Both front rims should present a similar temperature. Both rear rims about the same as well.


I user a thermal reader but a finger with saliva on it works okay. To prevent finger burns. Usually a dragging caliper may also emit a smell if dragging heavy enough.


Actually I periodically check my cars for any dragging calipers as it only takes less than a minute. This locates any that just have lighter dragging situation that you may otherwise never notice. Until they get worse.


You also do not have to remove a wheel for a hands on caliper dragging test. Just jack the tire off the ground. To allow hand rotating the wheel.

All of the things mentioned above work.

I jack the wheel off of the ground and spin the Wheel listen and feel. Then I have someone step on the brake and release. Then I spin it again and see if it frees up or not.

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84 300D, 82 Volvo 244Gl Diesel

A lot of times if you do have one dragging its because the brake hose is swollen shut internally

Brake lines can delaminate on the inside creating a one way valve... will let the pedal activate the brake.... but won't let it relax like it should.

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

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

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

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

The way calipers are supposed to work is that when the pad(s) moves outward, the square O-ring seal rotates slightly. When released, the O-ring is supposed to rotate back to pull the pad back. Sounds unreliable, but actually works fairly well, at least until the seal gets old and hard, but then it hopefully leaks to let you know. But internal corrosion could jam it too.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

If the Caliper is hot to the touch after heavy braking or stop and go city driving..It should just be warm to the touch and not hot enough to burn your skin.Another way is head directly to a car wash and hit the calipers with water while looking for steam .Ive had rear calipers sieze on me before and was left stranded and was out the cost of a tow. Replacing the rear calipers is more common on these old cars ,my guess is the pads last longer and will rust with age .

As a few people have already stated, replace the hose first if you suspect the caliper, they're bad most of the time because no-one considers them a wear item. They're usually like $7-20 online and not terrible to change. Start there. I'd do both fronts though if you're going to do it.

Also know plenty of people that have put a $100 reman caliper on an original hose and had the same problem. Even if you do the caliper, if you don't know for sure the hose was done recently, do it.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

I don't mess with brakes. Both old Mercs i've ever owned have had their brake systems fully rebuilt with new calipers, hoses, pads, rotors, and master cylinders.

The hoses in particular are what give me heart attacks.

You can get nicely rebuilt calipers from your friendly neighborhood Napa. I like this because I can return the cores without shipping.