Loose Timing Chain Symptoms - Explained In Full

You’re informed enough to know the risks of driving with a loose or stretched timing chain and are looking for confirmation that the chain is loose.

Before we get into the detail, the loose timing chain signs are

A Rattle When You Start The Engine

Misfiring
Low Oil Pressure
Decreased Fuel Economy

Erratic Performance
Excess Exhaust Smoke
Metal Shavings In Oil

Let’s look at each in more detail

Loose Timing Chain Belt Symptoms

A Rattle When You Start The Engine

A rattle on startup could be caused by many parts vibrating in sync with the engine. Therefore it’s important to get your ear down to the valve or chain cover area to see if the rattle is coming from the timing chain or not.

The timing chain tensioner is likely faulty as these need oil pressure to maintain the chain’s tightness. There should never be any slack on the chain.

The tensioner’s job is to ensure that happens, but sometimes they get clogged up with oil deposits, especially if oil filters and oil changes aren’t maintained.

The rattle you hear could be the timing chain hitting the top of the cover. If you are a competent DIY mechanic, remove the chain cover and inspect its top on the inside for scratch marks. If you see them, you know your timing chain is loose.

Engine Misfire

When your timing chain is stretched, it affects the timing of the valves operating in the cylinders. Any slight deviation in this precise timing will cause the engine to misfire.

The more loose the chain, the worse the misfire will be. This is because more cylinders could be affected. Although they are now rare, the ignition system could also not fire correctly in older cars with distributor caps.

Low Oil Pressure

Are you getting an oil warning light more often than before? Does it take longer to go off when you start your car?

The tensioners won’t be pushed against the chain if the pressure is too low, and the looseness will remain.

Decreased Fuel Economy

If the pistons aren’t working in unison with each other, it’ll result in inefficient fuel combustion. In extreme circumstances, you may notice a reduction in miles per gallon of up to 10 miles.

Erratic Performance

If the teeth on the camshaft and crankshaft gears have started to wear because the timing chain is loose, it will slip. When this happens, it may temporarily cause a reduction in performance until it catches a gear tooth again.

As time goes on, this erratic performance will increase. It’s important to fix the chain as if it does come off the gears; it can cause catastrophic damage to your car’s engine.

Excess Exhaust Smoke

A loose timing chain stops the pistons from working within the cylinder as they were designed to.

This can cause the fuel not to be combusted efficiently and result in it being discharged with exhaust gases through the tailpipe.

Metal Shavings In Oil

Pull out the dipstick and check the oil on it. Do you notice any metal fragments in the oil? If the belt is loose, it may be because the teeth on the crankshaft and camshaft are fragmenting. Not only does this cause slack in the chain, but it also affects the oil pressure.

As mentioned, if the oil pressure is low, the tensioners will not be pushed against the chain tightly enough. The tensioners only have a small hole for the oil to pass through. If it becomes clogged, low oil pressure occurs.

Can You Tighten a Loose Timing Chain?

Yes, you can, but with two caveats.

You really need to know what you are doing. This article won’t go into the process, but a great video goes into detail here. A key point to remember is to note timing marks before going further.

Even if you can tighten the chain within the manufacturer’s boundaries, it may be worth changing the chain anyway. If it’s stretched, it will only continue doing so and eventually need replacing.

What Causes a Timing Chain To Become Loose?

Years ago, timing chains used to last the lifetime of the car. However, as cars are now lasting for longer, this is no longer the case.

The fact that timing chains are not made of the same quality steel they used to mean that they naturally stretch over time.

Many chains have over 150 links. If each stretch 1mm over time, a 1.5 cm increase in the chain length will occur.

How Long Can a Loose Timing Chain Last?

Very difficult to answer. Without taking off the chain cover and inspecting the condition of the gear teeth, tensioners, and the chain itself, it’s guesswork.

It may last thousands of miles more or could snap the next time you drive it. If it’s stretched, it’s best to get the car checked ASAP.

A new chain, gears, and tensioners will be a fraction of the cost of an engine rebuild if the chain snaps.

What Happens If The Timing Chain Is Loose?

It is possible your car will suffer misfires while driving if the timing between the valves and pistons is wrong, which has a bearing on the engine’s firing sequence. A stretched chain can cause a cam or crankshaft gear to skip a notch, causing the timing of the engine to get out of sync.

Will a Car Run With a Broken Timing Chain?

A timing chain’s job is to synchronize each piston’s intervals up and down in each cylinder. If it’s broken, the pistons won’t move, no fuel is burnt, and the car won’t move.

Other Parts That Need Replacing At The Same Time.

Labor is the main cost of replacing the timing chain. Three hours of labor can add up to $450. Once the mechanic has access to the chain, you should replace your car’s tensioners, camshaft gear, and crankshaft gear.

Gears can be stretched slightly too – although rare – so for a cost of $40 per gear, it just makes economic sense to do this.

How Long Does It Take To Replace A Timing Chain?

An experienced mechanic will take 3 to 4 hours to replace a timing chain. Someone with limited knowledge will take longer. This time includes the time needed to replace other parts, as mentioned above.

If these parts aren’t replaced at the same time as the chain, expect the job to take no more than three hours.

Many visitors also read this related article: Car Feels Different After A Timing Belt Change – ANSWERED