Top 5 Strange Odors That Can Mean Trouble With Your Motorcycle

engine smells mean trouble for a motorcycle

It’s true—that schnozz of yours can be a powerful tool for something besides smelling the pizza

Do you have a nose for trouble? I mean literally. If so, it could be a very valuable asset. Believe it or not, strange odors emanating from your bike can be effective early warnings—even if you don’t have a particularly sensitive sense of smell.

It may sound strange but it’s a fact that certain potentially serious mechanical problems with your motorcycle may give you an early warning by how they smell!

For example, if you have a liquid-cooled engine, you may be able to smell the super-sweet odor of coolant even before you can see where it’s coming from. That doesn’t always mean a leak—overfilling or overheating the coolant may cause some to come out the overflow, but if that isn’t in evidence, consider the possibility of a water jacket or plumbing leak.

antifreez smell means trouble on a motorcycle

Or, if overheating is evident, maybe it’s time to check the coolant level, have a new thermostat, or clean the bugs, leaves, and other detritus of the road out of that radiator. BTW, I put window screening over the radiator on my liquid-cooled bikes to help prevent the latter problem.

I had that happen a few years ago with one of the liquid-cooled bikes I was in the process of restoring. The bike was old and after sitting dormant for years, the restoration of hot coolant flowing through the coolant lines when I finally got the bike running and out on the road for one of its first rides post-resto, one of the clamps was no longer tight enough to hold.

Coolant started weeping out and at a stop sign, I caught that florid odor of coolant. No damage done and tightening the clamp solved the problem, but sometimes a little leak can become a big leak in a hurry.

That strange odor along with white, steam-like vapor or smoke coming from your exhaust may be telling you about a blown head gasket.

A dragging brake pad or locked up caliper may be given away by the acrid smell of a super-heated brake pad. It’s a difficult odor to describe, but you’ll probably know it when you smell it. The other odor that may be present is the odd, metallic odor given off by a hyper-hot brake disc. In either instance, there may be a small, almost imperceptible amount of smoke produced.

brake burning the smell means trouble motorcycle

With or without smoke, the odor is pretty pungent, so if you get a whiff of it, checking on the source is important. Very carefully put your hand near, but not on the caliper and discs to see if those are inordinately hot. On older bikes, broken return spring in a drum brake system can also cause brake shoes to drag and get overheated and wear out prematurely.

You’ve probably experienced the burning brake lining odor if you’ve ever been following a large over-the-road truck and one of its trailer brakes is dragging. I’ve experienced it most often when behind an eighteen-wheeler in stop-and-go heavy traffic. You may also have experienced the intense odor of burning rubber if a trailer brake has locked up solid and the tire is skidding along.

The heavy almost tar-like odor of burning oil may be the first sign of a blown gasket, leaking oil line, or oil cooler leaking oil on a hot exhaust pipe. That same odor coming out the exhaust pipe along with blue smoke may be an indicator of severe engine wear, a broken oil control ring, or other internal engine problems.

Oil and other gunk can also occasionally be burped out of an unplugged crankcase breather line, which doesn’t necessarily mean big trouble, but if it is pumping out oil regularly, may be worth checking out.

oil smells mean trouble on a motorcycle

The familiar smell of raw gas is an urgent warning sign that you may have a fuel leak someplace—perhaps from the tank or cap, fuel petcock, a fuel line, leaking line connector, in-line fuel filter, carburetor overflow line, carburetor body, float bowl or fuel injector/throttle body, depending on your system. Fuel system leaks are potentially dangerous, so finding out where the odor is coming from is an ASAP item.

Most alarming is the smell of smoke as in burning insulation from wiring, seat material, plastic or any other material that smells “hot.”

I once was riding one of my old Hondas up in northern Wisconsin and the bike suddenly stammered, stuttered and stalled. When I pulled over I immediately caught the alarming smell of burning plastic and some smoke coming out from under the seat! It turned out to be melting plastic caused by a wrench from the under-seat tool kit that slid out of the tool kit tray onto the battery, which shorted out across the battery terminal and frame.

You might not have thought that detecting strange or unexpected odors can be part of your toolbox, but it’s true. This, in conjunction with any strange sounds you may be hearing coming from your bike, can help identify a problem before it leaves you out on the road someplace or does major, high-priced, or even dangerous damage to your bike.