What is the difference between serpentine belt vs timing belt? It’s significant, particularly for the car owner, who often handles routine maintenance.
The main difference between these belts is that serpentine belts don’t have teeth, connect the alternator and A/C compressor to the engine, and are placed outside the engine.
The timing belt maintains accurate ratios between the camshafts, and crankshafts have rubber teeth and are placed inside the engine. Though they have quite the same life span, the timing belt is costlier to replace than a serpentine belt.
Article Summary
What Is a Serpentine Belt?
This long, continuous rubber belt runs through the engine and powers all your accessories. It’s appropriately called a serpentine belt because of the way it winds around many different pulleys, like a snake, to operate:
- The alternator
- Power steering pump
- Air conditioning compressor
- Water pump (in some vehicles)
This machine facilitates your vehicle’s full functionality by keeping each integral part running smoothly.
A snapped or failing serpentine (also known as a multi-v or belt) can lead to a sudden loss in power to important systems, like your power steering, or cause your battery to die while you’re at speed, which is highly dangerous and inconvenient.
What Is a Timing Belt?
The timing belt, by contrast, is a more specific and critical component: its purpose is to keep the crankshaft and camshaft(s) in the engine synchronized so that the valves open and close at the appropriate moment in the firing cycle.
Without the timing belt, neither the engine’s valves could open or close at the right time which is usually sufficient to render the engine inoperable.
Unlike the snaky-looking serpentine belt, the teeth of a timing belt are designed to firmly engage the gears of the camshaft and crankshaft.
If it breaks, the pistons and valves can collide, causing very expensive and often irreparable damage.
Serpentine Belt vs Timing Belt Key Differences
The serpentine belt and timing belt isn’t the same thing and they have huge differences in terms of their design, appearance, and purposes.
Before deeply discussing what is a serpentine belt vs timing belt, let’s take a quick look at their key differences:
| Features | Serpentine Belt | Timing Belt |
| Working principle | Connects alternators, A/C compressors, and water pumps to the engine | Maintain accurate ratios between the camshafts and crankshafts |
| Placement | outside the engine | inside or behind the engine |
| Longevity | 60,000 miles to 100,000 miles | 60,000 miles to 100,000 miles |
| Design | Don’t have Teeth | Have rubber or metal teeth |
| Common signs of damage | Noise, wear out, Glazed appearance, too loose or tight | Noise, rough idle, low oil pressure, loss of engine power |
| Replacing cost | around $300 | $1000 or higher |
1. Working Principle
The serpentine belt connects the engine to various vehicle components, like the alternator. A crankshaft pulley drives it and delivers rotary motion to run various power accessories bolted on the engine.
It includes a power steering pump, oil pump, alternator, supercharger, vacuum pump, water pump, and A/C compressor.
Slippage is also allowed as various systems aren’t needed to maintain precise ratios with the engine rotating parts.
Timing belts deliver rotary motion to internal engine parts and maintain accurate ratios between the camshafts and crankshafts to avoid engine damage, bad pistons, and bent valves. Failure can occur if the ratios are interrupted.
Timing belts and chains maintain precise ratios by utilizing cogged pulleys and corresponding notches on the chain or belt’s inner side.
The timing belt should be lined up with the crankshaft gear’s dot marked. Otherwise, the camshaft may activate the firing orders of spark plugs, and crankshaft cycles won’t respond to each other.
2. Placement
The serpentine belt is placed outside the engine, and the timing belt is usually located inside or behind the engine.
So you can easily see the serpentine belt after popping the hood. But the timing belt will take tiresome effort to become visible.
3. Design
Serpentine belts can be either single or multiple V belts and don’t have any teeth. It is usually made of polymer rubber and has a soft surface to coil around the pulley of the crankshaft.
The timing belts have either metal or rubber teeth for timing cogs on the crankshaft. It can be made of fiberglass-reinforced or neoprene rubber and can endure extreme heat and coolant contamination.
4. Longevity
The serpentine bet’s lifespan isn’t much different than the timing belt. The serpentine and timing belts need to be replaced between 60,000 and 100,000 miles.
However, changing the timing belt is considerably costlier and more complicated than replacing the serpentine belt.
The timing belt turns the camshaft and operates the valves. Due to the placement behind a cover, the timing belt takes lots of labor to replace.
Some engines are also designed so that if the timing belt breaks down, the camshaft won’t turn. So, the engine can hit the open valves while turning, which can cause damage. Though the timing belt isn’t expensive, the tiresome replacement process makes handling it costlier.
The timing belt also remains hidden in the engine, and it cannot be observed if it wears out or gets sludge due to using the wrong oil or following a poor oil changing policy. If the timing belt fails, the engine may self-destruct in most cases.
Since the serpentine belt is external to the car’s engine, it doesn’t hurt the engine severely if damaged.
If the belt breaks down, the engine won’t self-destruct immediately. So you can drive the car for a short distance.
But the engine will overheat quickly without the water pump, so you can’t drive very far. A serpentine belt is relatively cheaper and easier to replace.
5. Repairing or Replacing Costs
It requires different time and effort to repair or replace the serpentine and timing belts, which is reflected in the maintenance cost.
Since replacing the serpentine belt is easier and quicker, it’ll cost around $300 for the job, including labor.
However, you may charge up to $1000 or higher to replace the timing belt for its more complex replacement process.
Remember, if you avoid the scheduled maintenance or don’t replace the damaged serpentine belt or timing belt, it can cause engine failure and expensive repair.
6. Impact of Failure
Serpentine belts can lead to accessory failure (e.g., loss of power steering or battery charging). On the other hand, timing belts can cause severe engine damage (e.g., bent valves, and engine failure).
When Should You Replace the Car’s Serpentine And Timing Belts?
The serpentine and timing belts show signs of getting damaged or becoming too loose or tight. For example, if the serpentine belt breaks, the water pump won’t protect the engine from overheating, and the battery will die. A damaged timing belt can cause the car engine to sputter when accelerating.
Serpentine Belt Symptoms of Damage
Noise: The car can make a distinctive squealing noise while turning on the engine or accelerating. Too loose or too tight a serpentine belt can also make this irritating noise.
Wear: Squeeze, pinch, and twist the serpentine belt to check for wear or frayed edges from all angles. If the belt becomes brittle or has small cracks, it needs replacement.
Glazed appearance: The serpentine belt must be replaced if it looks glazed or slick. It can result from cracking or overheating, and the belt won’t be able to slip properly.
The pulleys: The belt should sit on the pulley straight and aligned. If rubber deposits are on it, your serpentine belt starts to wear.
The belt tension shouldn’t exceed half an inch when trying to move the serpentine belt. If it moves, the belt is too loose and needs attention.
Oily belt: If the belt feels oily, there might be an oil leak somewhere, or it may slip on the pulley because of the oil. It needs a deep diagnosis.
Timing Belt Signs of Damage
Odd noises- if the timing belt makes a tricking or humming noise, it needs replacement. It’s a sign of wear out.
Rough idle- the timing belt may slip and encourage the ignition timing to run out of sync if some teeth break down. It may cause stalling or rough idle.
Low oil pressure– the teeth of the timing belt may break off and drop into an oil pan. It can reduce the engine oil pressure and end up with engine failure.
Loss of engine power- if the belt slips off snaps or pulleys, the engine can misfire or lose power. If so, you must replace the timing belt.
Which is More Important: Serpentine Belts or Timing Belts?
Both serpentine belts and timing belts have different jobs, and each is required for unique reasons. If the timing belts get damaged, the engine will not run.
Hence, the serpentine belt will become useless as it won’t drive any accessories on the engine’s front. In this case, a timing belt or chain is more important than a serpentine belt as it’s more essential for the engine’s operation.
In contrast, a serpentine belt isn’t severely essential for running an engine. If the engine depends on a serpentine belt to drive the water pump, the engine won’t perform for a longer time without this belt due to overheating. But the engine will run for a while.
The power steering, air conditioning, and alternators aren’t also strictly essential, as a serpentine belt drives them.
Though these components make the driving experience safer and more comfortable, an engine can run without these. So, the timing belt is more vital than a serpentine belt.
FAQs on
Should You Replace the Serpentine Belt When Replacing the Timing Belt?
Both the serpentine belt and timing belt have almost the same life span. Though they don’t directly affect each other’s performance, you should replace these belts simultaneously.
Can an Engine Run Without a Timing Belt?
An engine can’t run without a timing belt. It rotates the engine’s crankshaft and camshaft, allowing the cylinder to fire. If the timing belt fails, the engine won’t run and may stop working.
Is the Serpentine Belt the Same As the Alternator Belt?
The serpentine belt is also known as an engine belt or alternator belt. It gets these names due to its shape and how it snakes around the engine.
What Happens If a Serpentine Belt Breaks While Driving?
If the serpentine belt snaps, you could lose power to crucial systems, like your power steering, air-conditioning, and alternator. This can make it difficult to steer your ride, see clearly, and stay cool. You could end up overheating your engine, draining your battery, and leaving you on the side of the road.
Can a Serpentine Belt And Timing Belt Be Replaced At the Same Time?
These belts often do not necessarily need replacing simultaneously since they have different service lives and serve different purposes. But if one is getting replaced and the service shop or mechanic suggests that it makes sense to do both, especially if you’re due soon, think about it as saving on labor.
Final Words
As you can see, there are significant differences between the serpentine belt and the timing belt. Both belts have almost the same life span and are essential for an engine to operate smoothly and make the driving experience more comfortable.
So, you should keep both of these belts in good condition by checking and maintaining them routinely and replacing them before getting damaged completely. Though the serpentine belt will give a bit of time to replace, you can’t run the vehicle without a timing belt.
