Rattles and bumps can be highly annoying. What’s worse part not knowing what’s wrong or that it’s announcing to passengers that your car has an issue. The worst is needing to put it off and not being sure if it’s something that can wait or if you’re just making the problem more expensive by not prioritizing it. You need to know what’s causing the problem A.S.A.P.
So, here’s some common sense for you. (It goes without saying that we can’t diagnose your issue without seeing it, so use this advice at your own risk.)
You don’t expect a car to rattle when it is standing still. It may be something like the compressor clutch. The car also will make more noise moving than you’d expect too. A rattle or ticking noise may be due to low oil-it’s best to check your instruments.
If the rattle is under the car and sounds like shaking stones it’s possibly the exhaust system. If it rattles traveling over bumps in the road it indicates bad suspension. If the rattling disappears when you increase speed, for example go up a gear it may be linked to the engine being too warm.
The muffler rattling means that something is touching the exhaust pipe, possibly some corroded metal. This can also sound like a rumble. It should be dealt with as soon as possible and it will increase in severity over time. It might be something like the catalytic converter.
A gear rattle comes from the transmission and depends on the driving conditions. Sometimes the gear rattle may be confused with diesel knock. What is diesel knock? It’s given the less prosaic name of combustion roughness. The problem is linked to the high pressure of the combustion engine and is only to be found in combustion engines.
A lubricant will fix the problem. It’s possible that it will squirt out the fuel line so be careful.
A rod knock is caused by worn bearings – the crankshaft and the pistons rub together. Sadly your car will need a serious overhaul to fix the problem, the pistons and crankshaft may even need to be replaced. Many mechanics are confused by diesel knock, so it’s not good news at all.
Nor are bumps good news. The usual suspect tends to be the tires – it may be that the tires aren’t secured properly or that they are losing air pressure. Check the air pressure if you are unsure–they bear the brunt of rough roads and can be damaged enough to develop a slow leak. If there are stones stuck in the tire it will also feel bumpy, so inspect your tread carefully.
If it is more like vibrating than a general bump it could be a damaged CV joint; the only way to solve it is to replace the part. It is especially noticeable when you are accelerating. CV stands for constant velocity and the CV joint connects the drive shaft with the rest of the controls. It is not safe to drive the car if this part is damaged as it may turn into violent shakes if it is left alone.
A jerking movement may be a range of things so it will be hard to diagnose, you could have to check the spark plugs, the fuel injector or possibly the accelerator cable. If you can’t work it out it’s best to just take it to the mechanic. That could be said for any rattle or bump but now you know what you might be in for.