What all can go KNOCK

[Chapap]

I’ve searched, but haven’t found a general answer. Everything seems to be specific to someone’s problem. What sounds come from a bad engine?

can the valve train knock? I’ve always thought valve related problems were ticks.

can detonation knock? I’ve always described it as ping.

of course rods knock. Can they knock intermittently? Difference between rod/crank bearing and block/crank bearing?

anything else?

 

[Dirtman]

Ping, knock, detonation are all common terms for a similar problem, an unintended explosion in the cylinder. It can sound like a pinging noise or a knocking noise hence the terms. This can come and go depending on the engine load but generally if it happens enough you won't have an engine long enough to need to guess what the problem is anyway. Engines "knocking" from detonation aren't long for this world.

Rod knock is literally just that, the rod bearing is shot and the rod is literally knocking on the crankshaft or wrist pin. Usually not intermittent, constant clunky knocking noise like someone wants out of your oil pan.

The most common valve train noise is "lifter tick". Which is the result of a hydraulic lifter not pumping up properly. Can come and go depending on oil pressure, temp, or how the engine feels that particular day.
.
Exhaust leaks usually sound similar to a ticking noise as well. Constant never ending tick.

But most importantly, engines is goes vroom.

 

[Chapap]

So I have a knock. I thought it was a bad ac compressor but that’s not it. The timing belt was off a tooth and I had intermittent knock (meaning not a rod?). I fixed timing and now I have a steady knock. All this heard at idle while under hood. Can’t notice it driving, but I do have a loud exhaust hole too. Judging by the sound I’d say rod cause it’s a very solid, mechanical sound, but judging by the previous intermittentness I’d say detonation… but man is it a solid sound. Like hitting 4x4 with a hammer.

 

[RonD]

Engine "knock" is a lower sound than a "tick" sound

If you put a stick on the engine head or block you should be able to feel a rod or bearing Knock thru the stick, if you put you ear to the stick it will sound much louder

A valve train "tick" wouldn't be noticed that way
You can use a rubber hose as a stethoscope to ID location of ticks and knocks
Some Fuel injectors "tick" like crazy, Ford's can be particularly loud

A rod knock will almost disappear if you disable the spark plug in the cylinder with the bad rod bearing, the cylinder Firing is what makes the "knock noise" as the rod slams into crank journal
So you can disable one spark plug at a time and see if knock disappears, if so then yes its a bad rod bearing
BUT............there is always a but, lol, an exhaust manifold crack/leak at one cylinders exhaust port can sound like a knock, and disabling spark on that cylinder will also make the knock go away

Bad crank bearing knock won't go away with any cylinder disabled

Pinging is a whole other sound, often called "knocking" and sensors to detect it are called "knock sensors", lol
But its quite a different noise and "pinging" is the best way to describe it, or sounds like a Diesel engine, because diesel engines run by inducing self ignition of their fuel with high compression
So if you know what a diesel engine sounds like, that's pinging
Usually occurs in gasoline engines when accelerating

 

[97RangerXLT]

What all can go knock?

Jehovah's witness.

for your truck, the above is true.

AJ

 

[Chapap]

Well it sounds like I don’t have much hope for my knock being something anything other than a rod. Piston slap and knuckle noise seem like unique sounds too. I’ll have to get it professionally listened to. Are main and rod bearings a simple fix? Drop oil pan and everything is right there? Hopefully the crank isn’t damaged.

 

[Blmpkn]

Well it sounds like I don’t have much hope for my knock being something anything other than a rod. Piston slap and knuckle noise seem like unique sounds too. I’ll have to get it professionally listened to. Are main and rod bearings a simple fix? Drop oil pan and everything is right there? Hopefully the crank isn’t damaged.

Drop the pan and everything is right there? For the most part.

Simple fix? No.

If you have bad bearings, the best financial move to make would probably be to source another motor.

If your bearings are bad, it should be apparent in the oil. Drain it into a nice clean container and take a look. If it's all pretty and shiny looking than something is definitely fubar.

 

[Dirtman]

Or spend the $20 bucks to send it to Blackstone. They is tells you what be wrong.

 

[Chapap]

I didn’t believe it was possible to make such a bold and incredibly tactile sound, but I have a detonation problem. I tried the feel test with a ratchet extension and felt absolutely nothing. I tried pinpointing the noise and it seemed to come from the tippy top on the engine. I unplugged the left coil pack (original, I forgot to order two) to test each cyl by unplugging wires on the right pack (brand new). Didn’t hear much besides a poorly running engine. I plugged the left coil pack back in and the knock immediately started. I have another coil pack on the way. Will that help? Is this detonation damaging… Should I run on just the one coil pack for now?

Edit: engine wasn’t too happy with only one coil pack.

 

[1990RangerinSK]

I didn’t believe it was possible to make such a bold and incredibly tactile sound, but I have a detonation problem. I tried the feel test with a ratchet extension and felt absolutely nothing. I tried pinpointing the noise and it seemed to come from the tippy top on the engine. I unplugged the left coil pack (original, I forgot to order two) to test each cyl by unplugging wires on the right pack (brand new). Didn’t hear much besides a poorly running engine. I plugged the left coil pack back in and the knock immediately started. I have another coil pack on the way. Will that help? Is this detonation damaging… Should I run on just the one coil pack for now?

Edit: engine wasn’t too happy with only one coil pack.

No, it wouldn't be too happy. It's only running on three cylinders. So, it will run incredibly rough. To put it simply, an six cylinder engine will go

put put put put put put (repeat)

When you unplug one coil pack, it goes
put *** put *** put *** (repeat) (note that a put is a sparkplug firing, a *** is a spark plug not firing).

Is that bad for the engine? That's debateable. The three cylinders that aren't firing still take in fuel, and expel (unburned) fuel. Might be OK for the engine, likely NOT OK for the cat.

There's also the opportunity, given that you're dumping raw fuel into the hot exhaust, for a BANG!! every so often. I had that happen on my '85, once. I had just put a brand new muffler on the truck. For a few days, every time I let off the gas it'd backfire, but just a harmless POP! Then I let off the gas to slow down for a light, and it went BANG!! and got really loud. I pulled into a parking lot, looked under the truck, and my brand new muffler was split wide open. (I drove home, called the dealer (who had installed the new muffler recently) and asked about warranty. Service advisor asks me what happened, so I told him. He says "that's not covered")

 

[Dirtman]

No, it wouldn't be too happy. It's only running on three cylinders. So, it will run incredibly rough. To put it simply, an six cylinder engine will go

put put put put put put (repeat)

When you unplug one coil pack, it goes
put *** put *** put *** (repeat) (note that a put is a sparkplug firing, a *** is a spark plug not firing).

Is that bad for the engine? That's debateable. The three cylinders that aren't firing still take in fuel, and expel (unburned) fuel. Might be OK for the engine, likely NOT OK for the cat.

There's also the opportunity, given that you're dumping raw fuel into the hot exhaust, for a BANG!! every so often. I had that happen on my '85, once. I had just put a brand new muffler on the truck. For a few days, every time I let off the gas it'd backfire, but just a harmless POP! Then I let off the gas to slow down for a light, and it went BANG!! and got really loud. I pulled into a parking lot, looked under the truck, and my brand new muffler was split wide open. (I drove home, called the dealer (who had installed the new muffler recently) and asked about warranty. Service advisor asks me what happened, so I told him. He says "that's not covered")

It's a 2.3 not a 6 cylinder.

They can run just fine on one coil pack provided all the plugs and wires on that side are functional.

 

[1990RangerinSK]

It's a 2.3 not a 6 cylinder.

They can run just fine on one coil pack provided all the plugs and wires on that side are functional.

Oh. Is it one of the dual spark ones (with two spark plugs per cylinder)? Because, yes, that will go put put put put (repeat), assuming that the second coil pack controls the second plug in each cylinder. Otherwise, it will go put *** put *** (repeat).

 

[Dirtman]

Oh. Is it one of the dual spark ones (with two spark plugs per cylinder)? Because, yes, that will go put put put put (repeat), assuming that the second coil pack controls the second plug in each cylinder. Otherwise, it will go put *** put *** (repeat).

Yes one pack controls 4 plugs on the exhaust side, one pack controls 4 plugs on intake side. Only one pack fires during startup (I can't remember which side) after the engine fires up both coil packs fire but it will run fine with only a single coil since all 4 cylinders still have spark. The secondary coil pack is for better power but not necessary for the engine to actually function properly.

 

[Chapap]

The right side is supposed to be the main pack. There must be a reason there are two plugs per cylinder. I didn’t run well with one set after all… but I’d say I’m only at 90% potential at the moment. Not sure where to go from here tho. Fuel is the only thing left. Maybe the exhaust leak is severely affecting the way the engine is breathing.

 

[Dirtman]

The right side is supposed to be the main pack. There must be a reason there are two plugs per cylinder. I didn’t run well with one set after all… but I’d say I’m only at 90% potential at the moment. Not sure where to go from here tho. Fuel is the only thing left. Maybe the exhaust leak is severely affecting the way the engine is breathing.

Dual plugs make more power that's the only reason for it. If it wasn't running good on one pack then something was wrong with that side (bad plug, bad wire, faulty coil). Thats kinda the downside of the dual plug system, something can go wrong and you never know because the other side can compensate and mask the issue. That same engine ran fine on 4 plugs for 20 years before the DIS ignition and dual plugs were added.