I posted this earlier. weather the van is in gear or out of gear, driving or braking, as soon as it pass 50 mph it starts to make clunking noises from under the engine. not particular to one particular place but mostly from under the passenger footwell, then under the engine itself and sometimes a quieter noise from under the driver seat area. the noises sound like a chipping of metal or a quick and short grinding noise.
YES
The rattle you are talking about sounds like what we in the auto industry call "Pinging and Knocking" this can be caused by using low octane gas, engine timing is out of adjustment and or a few other engine tune up issues. If the rattle feels like it's only when giving it gas going up a hill where the engine is really working it could also be crack shaft bearings or connecting rod bearings that are about to give up the ghost. Big bucks.
chances are the battery is out of wack or the engine could be flooded
It is a common problem for shevy. Usually the Fuel regulator. Or for other vehicles it could be a dirty fuel filter
It could have a leaky carburetor or injector that's causing the engine to flood.
is the computer setting a code or check engine light, if not it could be your crank sensor.
check the cat shield it may be rotten and rattling If the sound is coming from the engine compartment (or sounds like it might be)and rattles mostly without the clutch pedal being used, but seems to rattles less or even stops with the clutch pedal depressed, it could be the throwout bearing going bad on the clutch assembly.
The word, rattler, implies the rattle snake. It could also mean something that rattles.
It depends on the failure. It could be on immediately or it could take days.
There are a number of things that could be wrong with your Honda 1976 CB 550 Four if the engine power bogged down on the highway today. If it now rattles at all RPMS, barely takes off without stalling, and sounds horrible it could be something as easy as needing a system flush. To best know what the deal is have a mechanic run a diagnosis test on the car.
They use there rattles by simply moving the muscle in there tail. They use it to scare away predators.
If your engine is burning oil there is a good chance it won't pass a smog test. You should get it to a mechanic immediately as it's not only a danger to the environment, but possibly could be a danger to you.