Engine Knocking

volvo
740

#1

My Dads 92 Volvo’s engine is making a knocking noise and I’m wondering what the possible causes are. He doesn’t take that great care of it but it didn’t over heat or anything. It sounds like it is making a loud knocking or clicking noise directly from the engine when you accelerate. It still runs but definitely has a lack of power.


#2

There a big difference between what people will describe as a “knock” and a “tick.” Since you did both you’ll have to clarify - a deep, sort of thumping knock? Or an actual ticking sound. In addition, raise the hood while its doing this - operate the throttle if you need to to rev the engine - and see if it seems to be coming from near the top of the engine or deeper down like in the middle or at the bottom.

A tick will be at the top is probably a noisy valve train. This can just mean you’re low on oil or maybe that the valves need adjustment (though I don’t know whether they are adjustable on this car) or something like that.

A knock will be at the bottom and means that you start shopping for a new car.


#3

Has anybody opened the hood and checked the fluid levels, oil, coolant, trans, etc?

Ed B.


#4

ok, to clarify, it seems to be more like a clicking noise from the top of the engine. When it first started doing it the oil and coolant were low but that has been fixed. The engine only makes the noise while it is accelerating but not when it is coasting or idling. I guess I will check and see if the valves are adjustable? If anyone has any other ideas that would be great. Thanks


#5

How low was the oil? If it’s low enough, engine damage can easily result.


#6

not too low, just about a half quart.


#7

Sounds like it’s pinging. If it does it only when accelerating, does it should something like dice rattling? What octane gas are you running? Does it go away if you run high octane? Is the check engine light on?