Do bad wheel bearings get hot? - PeachParts Mercedes-Benz Forum

moorerp · #1 10-10-2008, 08:27 PM

OK, so here's the story. Bought an '83 300TD (with manual trans!) and don't get it 10 miles down the road when I see smoke coming from the front tires and detect that "hot" smell that associate with brakes. Stop the car, find the hubcaps and lug nuts WAY too hot to touch on both front tires.

Here's the question: is it more likely that both front brake caliper pistons have siezed up at exactly the same time, or that both front wheel bearings having crapped out at exactly the same time?

Question 2- has anybody had wheel bearings crap out and get REALLY hot in the process?

Thanks for the input- your info is going to help me figure out which method to use to get it from where it is now to where it needs to be.

cheers,
randy

Chad300tdt · #2 10-10-2008, 08:35 PM

I hope it's a hanging caliper. If your bearings are so bad they're heating the lug bolts, you'll probably need a new spindle since I'd bet they're fused to it.

Jack the front up and see if there's any play in the wheels.

Good luck. I hope your troubles are an easy fix.

EDIT: It would be likely to have both calipers freeze due to really beat brake fluid. I'd also change all the brake hoses while you're in there. Replacing the rotors will allow you to actually see and replace or repack the wheel bearings too.

Congratulations on the purchase. Do you have a Wagon or are you referring to a turbo diesel sedan? Post pics when you can.

cdplayer · #3 10-10-2008, 08:43 PM

I did once. My fault though. I repacked the new bearings and races with the grease I had always used on my earlier cars.
Did not realize you can not use "drum" grease on "disc" bearings. Way more heat to deal with.
Bearings overheated and began disintegrating. Ride felt like driving on a grated bridge. Hot hot hot.

Quote:

Originally Posted by moorerp

OK, so here's the story. Bought an '83 300TD (with manual trans!) and don't get it 10 miles down the road when I see smoke coming from the front tires and detect that "hot" smell that associate with brakes. Stop the car, find the hubcaps and lug nuts WAY too hot to touch on both front tires.

Here's the question: is it more likely that both front brake caliper pistons have siezed up at exactly the same time, or that both front wheel bearings having crapped out at exactly the same time?

Question 2- has anybody had wheel bearings crap out and get REALLY hot in the process?

Thanks for the input- your info is going to help me figure out which method to use to get it from where it is now to where it needs to be.

cheers,
randy

moorerp · #4 10-10-2008, 08:43 PM

Thanks for the reply- there doesn't seem to be any play in the wheels, and they don't turn absolutely freely. The weird thing is that once they cooled down a bit, I could turn the wheels by hand (although they were not entirely free)- doesn't seem like the brakes were sticking badly enough to cause that much heat after only 10 miles.

But it also seems that if the wheel bearings were that bad, then there should be some indication other than extreme heat (like the play you suggested, or some wobble while driving, or something).

mobetta · #5 10-10-2008, 09:21 PM

I've always heard/ felt in the wheel or my butt when the wheel bearings go bad.

unless someone did a repack on them and did it wrong, I think it unlikely that bearings on both sides would fail at the same time. maybe that is why they sold it?

didnt you test drive??

vwbuge · #6 10-10-2008, 09:33 PM

If you can take the calipers off and spin the wheel by hand you will know if you have a bad wheel bearing.

qwerty · #7 10-10-2008, 09:50 PM

Quote:

Originally Posted by moorerp

Question 2- has anybody had wheel bearings crap out and get REALLY hot in the process?

Bearings will also get hot if they are adjusted too tight.

BoostJunkie · #8 10-10-2008, 10:41 PM

You need to take the wheels off and tear into it a bit for signs of the trouble. Doing this will give you the direction to go in. Also, how did your break peddle feel leading up to this?

Chas H · #9 10-10-2008, 10:45 PM

I've seen wheel bearings get hot enough to melt the spindle in two. But I think you have some brake issues.

moorerp · #10 10-10-2008, 11:15 PM

Quote:

Originally Posted by BoostJunkie

You need to take the wheels off and tear into it a bit for signs of the trouble. Doing this will give you the direction to go in. Also, how did your break peddle feel leading up to this?

That's the rub- it's sitting in a gas station parking lot right now and I need to move it 40 miles to my house before I can dig into it- so the nature of the problem is pretty key to figuring out how I'm going to move it (towing, driving, flatbedding, etc.).

The breaks got very soft right before i stopped, but I think that's typical for very hot brakes. They were OK when I drove off from the buy.

moorerp · #11 10-10-2008, 11:18 PM

Quote:

Originally Posted by vwbuge

If you can take the calipers off and spin the wheel by hand you will know if you have a bad wheel bearing.

How will removing the calipers and spinning the tire reflect upon the wheel bearings? Without brake pads rubbing against it, it should spin freely, no?

Chad300tdt · #12 10-10-2008, 11:24 PM

Quote:

Originally Posted by moorerp

How will removing the calipers and spinning the tire reflect upon the wheel bearings? Without brake pads rubbing against it, it should spin freely, no?

Correct, but if the bearings are the problem, it won't spin freely.

Regardless, I recommend using a flatbed to get it home and repair it.

NY300SD · #13 10-10-2008, 11:27 PM

I had this problem when I got the SD, it was seized brakes. After a bit of city driving the pedal would go to the floor and the car wouldn't even slow down. The first time it happened to me I almost hit a cop!

Diesel911 · #14 10-11-2008, 01:14 AM

Quote:

Originally Posted by qwerty

Bearings will alos get hot if they are adjusted too tight.

The above happened to me when I tried to adjust the Front Wheel Bearings by feel instead of using a Dial Indicator as the Factory Manual states.
I had to pull off the hubs to get rid of the overheated grease; but found no damaged or discolored Bearings/Bearing Races.
If you have a Magnetic base or other way to mount a Dial Indicator on the Rotor I would use that the check the bearing clearance. If it is really tight you know what caused the heat.
If it is too loose you may have lost a bearing.
Either way the hubs should be pulled off even if only to replace the roasted grease.

If it is not the Brakes draging.
Also If both sides overheated I believe it is more likely the Spindle Nuts were tightened too much. The reason I say this is I think it would be unusual for both sides to have a wheel bearing failure at the same time. I guess the exception could be if the wrong grease was used in them even with the correct clearance.

rcounts · #15 10-11-2008, 02:34 AM

Quote:

Originally Posted by moorerp

...there doesn't seem to be any play in the wheels, and they don't turn absolutely freely. The weird thing is that once they cooled down a bit, I could turn the wheels by hand (although they were not entirely free)- doesn't seem like the brakes were sticking badly enough to cause that much heat after only 10 miles.

But it also seems that if the wheel bearings were that bad, then there should be some indication other than extreme heat (like the play you suggested, or some wobble while driving, or something).

Quote:

Originally Posted by moorerp

...The breaks got very soft right before i stopped, but I think that's typical for very hot brakes. They were OK when I drove off from the buy.

Based on these two quotes I'd bet twenty bucks its stuck brakes. Especially if the vehicle sat for any amount of time right before you bought it. I've seen vehicles that sat for as little as a couple of months have caliper pistons sieze in their bores or, more commonly, the calipers get stuck on the mounting bolts that are supposed to allow them to slide side-to-side and adjust as the pads wear down.

The last time I had a problem like this it was on my Jeep, which had been sitting for a few months. No indication of any problem to start with, but the driver's side caliper was stuck on its mounting bolts and couldn't slide. This caused the outside pad to drag lightly on the rotor, not even enough to make it pull or anything to start with. But after about 5-10 miles I noticed that it started pulling towards the driver's side and in less than 15 miles the outside pad got hot enough to actually catch FIRE! So you can bet your azz that they can get that hot after only 10 miles.

As you stated having the brakes work normally to start with and then loose their braking power is definitely a primary symptom of overheating brakes. If you aren't riding them, or doing any extreme braking, the most likely cause is that they are not releasing fully and are dragging.

I'd say that at this point the big question that needs to be answered is exactly WHAT is stuck and causing them to drag...