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Car makes noises or ticks with the engine running

Copyright 2011 by Morris Rosenthal All Rights Reserved

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The Omni Project

Cars are dangerous and can kill people who work on them - proceed at your own risk. Diamond symbols linked to decision text. I've also posted a series of flowcharts for troubleshooting laptops and PC troubleshooting.

Flowchart to diagnose car noises check for electronic noise makes noises only when cold checked for ticking bomb from cartoon only makes noise when rolling slowly checked for objects embedded in tire treads checked inside hubcaps for pebbles recently changed tires or added air only makes noise when car is turning noise frequency changes when car shifts only makes noises in reverse clicking or ticking coasting in neutral ticking or clicking noise when car is moving noise only occurs when car hits bump heavy clunk or knock vs light click

An Automotive Troubleshooting Flowchart for Clicks and Clunks

Is the noise a clunk or a single tick? Process of elimination is the best way to work through complex troubleshooting tasks. In this case, the main division of common ticking sounds is whether they are coming from the wheels or the engine. Single clicks, clunks and thuds don't really count as ticking noises, but I thought I'd at least mention them. Stray sounds are highly unlikely to involve the engine, unless they are related to engine movement under acceleration. Try sitting in the car with the engine off and having somebody push down on the bumper or the trunk a few times, and see if that causes the noise to occur.

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Does noise only happen when the car hits a bump? If the click or the clunk only happens when you drive over a bump or a dip, it's probably related to the suspension or the body shifting. Modern cars are held together by spot welds, and a single failed weld might be enough to create a noticeable sound when the unibody flexes just so. The struts or shock absorbers, springs and other suspension parts are also suspect, but you'll often be able to replicate the noise without the car running by bouncing that corner of the car. Sway bars in rubber bushings or torsion bars in rubber sleeves in a protective tube can also make loud clunking noises as they twist or relax, cutting off some of the rubber sleeve may be the only solution if it bothers you that much. The manufacturers will be aware of any such design flaw sounds, and you should be able to find instructions for relieving them, even though they are unlikely to result in a recall.

If the clicks or clunks aren't involved with bumps but seem to occur randomly when going down the road, a loose bolt or ball joint may be at fault. Make sure the bolt holding the shaft of the lower ball joint (mounted on the control arm) in the wheel assembly or spindle is tight. Try shaking the tires, both on the ground and with the car jacked up, to see if you can replicate the noise. With the car on jack stands, get somebody else to shake the wheel by the tire while you watch the linkages with a flashlight. Have somebody steer the wheels back and forth (remember they'll need the key or the wheel will lock) and keep a close eye on the tie rod ends, steering knuckles and ball joints for slack at the start of movement. If you get a clunk in the steering and it's coming from inside the rack due to wear of the rack and pinion gear, replacing all the parts outside the rack isn't going to help. If the clunk only comes on heavy acceleration, check the motor mounts.

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Can you hear ticks only when the car is moving? Here's where we start to separate old car noises causes by wheel rotation from ticking noises cause by the running engine. Some engine ticks may only occur when the engine is under load, so if you don't hear the ticking noise when the car is idling in park or neutral, find a safe spot in the driveway or the street with nothing in front of you and try giving it some gas in drive with your foot firmly on the brake. You're just trying to get the torque and the RPMs up a little to see if the ticking noise will start, don't kill somebody or smash into the garage.

When it comes to isolating noise in the engine compartment, good directional hearing is a great help. I like to use a cardboard tube or a pipe to help try to pinpoint where sounds are coming from, or a long screwdriver pressed up against the metal of various parts, with my ear to the handle. It doesn't work anything like 100% of the time, but it's better than just sticking your head wherever you can force it and getting your face dirty. Keep in mind that exhaust leaks can sound just like metal tapping, especially on the manifold.

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Do the ticks persist with the car rolling in neutral? If you hear the ticks rolling in neutral, you can assume it's not transmission noise, which is the best news of all. It could still be an engine tick as long as the motor is running while you're in neutral, but I don't advise you fool around with turning off the ignition while rolling down the road because you may misjudge your ability to stop the car without power brakes or turn the wheel without power steering, and you never know what's going to jump out in front of you. And remember the steering will lock on fairly small movements in most cars if you turn of the ignition.

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Do the ticks only appear with the car in reverse? I threw in the issue of ticking in reverse due to brake adjusters or a problem with the parking or emergency brake only to illustrate the odd case, of which there are always dozens if not hundreds of possibilities. It's also possible you have a problem with the reverse gear of the transaxle or transmission. But in the mainstream of problems, the big clicking noise generators are rotational noises from the wheels or engine, and exhaust leaks.

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Does the noise frequency drop when the car shifts gear? If you have a continual clicking noise that slowly builds frequency (goes faster) as you accelerate and then drops when the car shifts gears, you can be confident that it's not related to the wheels, whose rotational speed is directly proportional to the speed of the car. That leaves power train noises, with the most likely culprits to be a exhaust manifold leak, a small crack in the forward exhaust pipe, or a genuine engine tick. Don't be shy about getting other people to listen and try to pinpoint the noise, we all have different hearing abilities in different ranges. Just make sure nobody burns their faces or gets their hair or loose clothing caught in belts or pulleys.

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Do the ticks only show up during turns or when the road curves? If it only makes noise going around corners or in curves, it's often an indication that the CV joint bearings are failing. Frequently, a failing CV joint will also produce a very convincing "clank" if you turn the wheel all the way to one side at slow speed, like in a parking lot or pulling out of the driveway. Less scary old car noises include things rubbing on a slightly warped CV boot or axle, and scraping sounds can be caused by tires that are too big for the wheel wells, or wheel wells that have sustained damage in an accident and are now in the way of the tires at the maximum turning radius.

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Have you just changed tires? Rotational noises from the wheels fall into a couple classes as well. The most embarrassing one is if you rotate the tires or have one off to look at the brakes, and forget to snug the wheel lugs up after you set the car down. Sometimes this creeps up on an old pro if you loosen the lugs for both front wheels on the ground, jack up the car, and inspect the brakes on just the one side. Good chance of only remembering to tighten the lug nuts on that side after setting the car down. Never drive around on loose lug nuts, the wheels will quickly eat through the studs and then you'll have both an accident and a nasty repair job.

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Have you removed the hubcaps? Gone are the old days of metal hubcaps surrounded by spring tabs of steel. Today's hubcaps are generally plastic and held in place by a large wire ring which snaps into little plastic towers on the back of the hubcap. If the hubcap is loose, the wire ring may make a little noise on rotation, and if the hubcap uses multiple wire springs, one may loosen up and rattle away on its own. In any case, try taking off all the hubcaps and see if your noise goes away. By the way, if your hubcap falls off in a pothole and the plastic towers get all bent up, you can often reshape them so they'll hold the wire ring by using a heat gun.

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Did you inspect the tire treads? There's the simple case of pebbles or nails caught in treads, which may lead to the tire deflating when you pull them out. You can eliminate a lot of possibilities by either putting the whole car up on jack stands or jacking up one wheel at a time, and spinning each wheel. That will localize any noises related to the particular wheel bearing, CV joint, or rotor and brake pad combination, and eliminate any rolling ticks caused by tire issues.

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Are the ticks only present at slow speed? Then there's the classic warped rotor click, which may go away after driving a short while as it pushes the pads and the caliper piston back, only to return after the next full stop. I'd suggested checking if the rotor is overheating, but I've burnt my fingertips so many times doing this that I can't, in good conscience. The really frustrating case is if you have any sort of hollow wheel decoration, hub cap, etc, that is open on the back and bolted onto the wheel. My rally wheels used to have such a decorative center that always picked up pebbles, that would bounce around until the car picked up sufficient speed for centrifugal force to keep them in place.

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Is there a time bomb under the seat? Finding a ticking time bomb under the seat or in the glove compartment isn't all that common either, they normally go off BEFORE you find them. Google may be of use in finding instructions to defuse a ticking time bomb, but my top priority wouldn't be surfing the web. If you escape alive, the troubleshooting problem you're faced with is figuring out the who thought you were worth the effort of blowing up.

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Does the car only click when it's cold? Engine ticks that you'd swear are rotational turn out to be exhaust leaks, more often than not. Very loud clicks that get softer as the car warms up can be from the exhaust manifold, or from an apparently healthy exhaust pipe that's cracked at a"Y" weld under the engine on opposing cylinder or "V" engines. A missing broken bolt or broken loading spring on a bolt at the exhaust gooseneck at the exit of the manifold can also be at fault. Solid lifters often chatter and make noise until the oil gets circulated, but lifter rap is sometimes easy to diagnose by listening at the valve covers. If you have the fill cap on the valve cover of an inline four or six, removing the cap should make lifter rap very apparent. Any of the camshaft drive accessories can cause make noises. Other clicking candidates include pulleys that are bent or loose and are contacting something. . Watch them with the engine running and look for rubbed spots with the engine off. Any loud clicking sounds coming from the bottom of the engine listening at the oil pan are bad, likely bearing related.

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Are the windshield wipers and radio turned off?

I dropped in the bit about the windshield wipers and the radio to test if you're awake - really to remind us all that troubleshooting begins with common sense. If you always have the radio on and the amplifier is picking up the spark plugs firing or intermittent surges from the wipers, turn of the radio (or the wipers). And above all, if you only get the noise when there's a passenger in the car, before you blame it on weight distribution, make sure the passenger isn't some nervous nelly tapping away on the roof with five fingers. You should always stick your head under the car for a look (not while it's rolling) before you try armchair logic to reach a solution. It's entirely possible that a plastic band from a newspaper bale or a green branch has wrapped around an axle and is tapping on the undercarriage. If you're super sensitive to noise, it's even possible that you're hearing a vibration from loose change or such right in the passenger compartment.

It's entirely possible that the most common ticking noise is the sound you get from a slowly cooling exhaust system when the car is hot during the summer and you turn it off. If the car is making metallic ticking sounds for a couple minutes after you shut it off, it's just the exhaust system contracting as it cools down. It's much more common on opposing head or "V" engines, where the pipes are joined together in a welded "Y" before going into the catalytic converter.A dual exhaust system with independent converters, mufflers and tailpipes may still have a crossover pipe of some sort for equalizing pressure, which can also lead to clicking noises when pipes cool at different rates.

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