Burning smell

hummingbird · July 10, 2016

We drove our new-to-us Class C motorhome two times about 60 miles each time -- no problems. Our third trip was longer and included some rush-hour driving through a city (lots of braking).

We noticed a smell like burning brakes. At first we were not sure it was us, but the smell persisted. We pulled over at a rest area and phoned the shop that had inspected our rig prior to purchase. They had no suggestions other than brakes, heat gauges, and transmission -- all of the gauges were normal for heat; the transmission seemed to be shifting well; brakes were working fine. The shop tech had no more suggestions.

The smell persisted for the rest of our drive (200 additional miles). It could just be residual from braking during the rush-hour traffic.

We are planning to leave on a long trip tomorrow -- does anyone have any ideas about the source of the smell? Do we risk a problem?

I'mdonewiththis forum · July 10, 2016

It depends on what is causing the smell if it will be a problem. Is it stronger by a front wheel?, rear wheel? Have you checked temperatures of the brakes? When you smell it put the back of your hand by each wheel and see if there is one wheel that is hotter than the others. It sounds to me like you have a brake hanging up, either a caliper (front) or maybe a parking brake (rear).

rdickinson · July 10, 2016

Were you leaning on the brakes while going down a hill? I saw this happen recently coming back from Idaho. A woman in a Volvo car pulling a trailer going down a long hill had her foot on the brakes the whole time.

I would get a laser temp gun, they are available in lots of parts supply places plus other locations, Raytheon makes them amongst others. Aim the red dot at the drums and or hubs. If the hubs are covered by a chrome cap and the drums are not exposed shoot the backs of the drums from underneath the other side of the MH. I'd be looking for one wheel considerably higher temp. than the others.

Using your hand would work but the Temp gun is more accurate and will prevent burns to body parts.

The sunny side of the trailer will be warmer than the shady side.

Mine are generally lower than 100 degrees f.

https://www.amazon.ca/HDE-Temperature-Infrared-Thermometer-Laser/dp/B002YE3FS4

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On edit, do you have a driveshaft brake like my old IH 4700, was or is it on partially? if not was your emergency brake on?

Just trying to rule things out.....

Jimalberta · July 10, 2016

Hopefully you are not one of those people who drive with their left foot resting on the brake pedal?

oldjohnt · July 10, 2016

Assuming its hot brake and not hot rubber smell, I've seen MANY motorhomes that set idle long time periods (typical for an RV) have brake calipers that stick and don't fully release from lack of exercise and rust and corrosion. If it were a front on one side only (typical) the steering may pull in that direction. If any (disk or drum) are hanging, the wheel and hub can get very hotttttttttttt which a feel or smell or better yet a temp gun can locate. If a rotor or drums got extremely hot from hanging, Id be afraid to go on a long trip until it was repaired. Rotors will show if they have been too hot.

Parking brake cables can stick due to corrosion and lack of use and the hot area or its smell depends on if its rear drum brakes (or disc with drum parking brake) or a driveshaft brake behind the transmission. I LIKE A DRIVESHAFT BRAKE BETTER, Ive had less cable or linkage problems then in a longgggggggggggg cable all the way from front to back of RV

I just bought a 2006 MH with very low miles and a couple of the rotors show signs of being overheated and it sat a long time so to be on the safe side I'm replacing ALL FOUR calipers and pads now and as often as I use mine I should be good to go for yearsssssssssssssssss.

Look, listen, touch, smell, its possible it may free up (if its a hanging brake) ?? but be careful and observant and see if its pulls to one side and you could "get by" for a short trip.

John T

I'mdonewiththis forum · July 11, 2016

I wasn't suggesting touching the hub/drum/rotor. I meant put the back of your hand close to the hub and you will feel a difference. The exact temperature isn't really important. Locate the hot wheel and get it repaired (if that's what it is).

rdickinson · July 11, 2016

On reading your first response, you are correct. You said put it 'by' not on. This or a similar topic came up a year or more ago and as I recall reference was made to touching a drum or hub.

I'mdonewiththis forum · July 11, 2016

Either way, Hummingbird let us know what you find out.

rdickinson · July 11, 2016

I hope so, many of these problems which may eventually get resolved are not posted and we never know.

hummingbird · July 25, 2016

Problem solved.

The first time we noticed the burning smell, we had been driving in stop-and-go traffic for about 45 minutes. We pulled into rest area to check things out and stayed long enough for brakes to cool.

A few days later a second burning smell occurred, this time while descending a steep road from a mountain pass. I noticed the vehicle wanting to pull to the right, so I put my hand near the front right hubcap. (Not on the cap -- thanks to the advice given in your postings!! That probably saved me a burned hand, as the hubcap was extremely hot.)

We deduced that the two incidents were related and were able to find a repair shop that could look at our brakes. The verdict: a caliper that stuck when the brakes were hot. The mechanic showed me the caliper and it looked damaged. Luckily the rest of the system was okay. A few hours delay we were on our way.

I would like to make a recommendation for anyone who is in the Helena, Montana area and needs mechanical repair -- go to R & R Diesel Repair. They did a great job for us on very short notice at a reasonable cost and kept us on the road.

Hummingbird

I'mdonewiththis forum · July 26, 2016

Good to hear that you got it fixed! At least you didn't do like I did once. I had a caliper stick on an F-150 I had and got mad enough that I drove it to a place that could fix it (I was 60 miles from home). By the time I got to a repair place it got hot enough to burn the fiber piston enough to cause me to not have any brakes. They even left the spindle hang out in the open air for a couple of hours to cool!