Has 157k miles. You start it up and the engine revs up a little and the knocking noise is pretty loud and after a minute it still knocks just not as loud.
Its loud when you accelerate but if you let off the gas and coast with no load on the engine you can hardly hear it. The noise sounds like its coming from the cylinder head. Check engine light it on. Pulled the code and it say number 2 cylinder miss fire. Not sure if that might be why it idles rough.
Does this sound like a VVT issue? I pry back the upper timing belt cover to see if there was any oil leaking. looked dry.

Any suggestion short of blowing it up??

 

If you have a misfire code, then you should run with that. try and swap coil packs to see if the misfire moves to the other cylinder - or if you've never replaced the coils in 150K miles, simply replace them and throw in new plugs (coils give up at about 100K+ miles). PS on the plugs, don't go over the top, standard copper core work just fine for 1/3rd the price.

 

How would a miss fire cause suck a loud knocking noise? Had vw 1.8t that had a bad miss fire problem until vw replaced them. Never made a knocking noise just idle rough which the s40 does. I know vw and volvo are different animals.
Far as I know the coil packs have never been replaced.
I should also add there seems to be some power lose. Which if one cylinder isn't firing that could do that.
I'm just not up to speed on Volvos as i am VW lol
Is volvo still using the fire box on this year?

Thank you for the replys

 

Hey.
So my friend has a Dodge Caliber SRT4, He had the car for quite a while until one day he had it go into limp mode on him. He cleared the code which was a mis fire code and noticed that when he floored it the car wasn't right and sometimes immediately put the CEL on.
If he was doing 100km/h in 6th it was dramatically worse when he matted it the car chugged and stuttered and was not happy at all. Much less noticeable if you shift down and matt it.

Anyways the fix was the simplest thing, spark plug gap. We pulled his plugs checked the gaps and went to a .28 gap on them all and the problem was gone.
As the plugs get older the gaps widen out. Also the noise could be either the mis fire or the compression washer on the spark plug is failed or has some debris in its way. Doesn't take much debris to cause the compression washer to not properly seat and seal.

Take your plugs out, check them, check their gaps, gap to a .28 or .30 either are fine just try to get in that range. (Stay at or above .28 and at or below .30)
If the gaps and plugs are good clean the area they sit in very well, then put them back and torque to spec or use the DIY torque spec which is tighten her till she's ok.
Some compressed air wouldn't hurt to help blow the stuff out of the area so your compression washers can seat properly in the hole.

Checking and gapping then cleaning the plug hole is all free so do that before tossing wires and coil packs at it.
My moneys on plug gap to large, The turbo cards need a smaller gap and get unhappy when its to large because the forced induction is to hard to overcome for a large gapped plug. Hence closing the cap helps the spark plug spark right and no more miss fire.

 

I'll try to mess with it this weekend if time permits.

 

(Is your car turbo? Naturally aspirated engines don't care as much about spark plug gap. But they do care.)

To check the wires go out at night. Open the hood, start the car and look at the wires. Make sure you can see every bit from start to end.

Look for spark jumping out, if it is the wire insulation is degraded to much and since power escapes some gets to the plug but it's to little and also to late and so it doesn't fire at the right time and isn't enough power anyways even if it did get there on time since so much escaped.

Otherwise, if the plugs are good, wires are good, go to the coil pack.
Generally the coil pack works or it doesn't, if it works the car starts if it doesn't the car may start but you know it's got 1 cylinder less. There isnt really a "the coil pack is going" sign it just goes and you now running on 5 instead of 6 cylinders. Or if it goes on 2 or more plugs the car won't start.

 

Its non turbo 2.4I
I don't think its the coil pack causing my main problem with the knocking noise. (I think I have more then one problem) Almost starting to wonder if it might be collapsed lifters. Soon as I get some space cleared out in the garage I'll pull it in and wait for motivation to come over and help. I'll check the basic stuff before pulling the valve/cam cover.

 

Spark plug compression washers can cause loud and exessive noise when they fail to seat properly.
The gap on them isn't to much of a worry in non turbo but it can still affect it, mostly only noticeable in the reduced gas mileage on a non turbo.

Check wires, On damp night bad wires you can really see the spark escaping bad wires. But as long as it's dark you don't need damp/wet.

Lifter tick could be it, or low oil? Lifter tick usually goes away when warm. Unless it's a larger issue or you have super hearing.
The noise is forsure from the top? Lack of oil changes can pre mature wear out the main bearings down in the bottom end.

 

These are not hydraulic lifters so cannot collapse. It's an overhead cam engine where the cam lobe strikes a cup that sits over the valve stem. The thickness of the cup surface is how you adjust the gap between cam lobe and valve stem.

The sound you describe makes me think rod knock. How is your oil level?

 

Well that's pretty easily figured if he just listens down low and hears bottom end knock.
I had a 1994 Jeep Grand Cherokee that had 550,000km and a nasty connecting rod knock until it broke on the highway, tossed the parts out the bottom oil pan. It lasted like that on 7 cyl and no oil until I got it home.

Also lifter tick doesn't sound horrible like a rod knock. Lifters up top, rod refers to bottom end connecting rods. Engine oil pushes threw main bearings in your rods and that creates the engine oil pressure.
The main bearings wear and then the bearings and rods slap eachother as the crankshaft spins until eventually the parts break and then your down a cylinder as that one or more than one is no longer connected to your crank shaft cause the loose main bearing caused the connecting rod to beat itself till it broke.
If you have rod knock it's a rebuild for that engine then, also very horrible noise and easily located just listen up top and down low.
Rods are low anything else is up top.

If rod knock, You could pull the engine, flip it upside down, do the main bearings and call it a day. But honestly at that point do the whole engine or nothing if it's the main bearings / connecting rods.

As I and Hudini mention, how's your engine oil level?

 

I finally got to mess with the car today. Pulled the spark plugs and found cylinder number 4 and 5 didn't have a compression washer on them.
Its also on the side that seems the loudest so you might be onto something here. Also had mix match spark plugs. Not sure who worked on this car last but I like to kick them in the ***** or vage.

Have another question. When I had the car running I took off the oil fill cap and got a big rush of air that shot out when I pulled it. Something is telling me that's not normal?

Well report back once I get some new plugs.

 

update:
ok but in new spark plugs and it didn't fix the problem. Tho its sounds more of a loud tapping noise now. Now I just got to think weather or not I want to pull the head off or not.

 

as to the rush of air out the filler cap, that could be a sign the PCV system is clogged. Check out RobertDIY's video on Youtube about how to test for the PCV system (including the "rubber glove" test where you put a "surgeons" glove over the filler cap to see if it inflates or pulses in and out...

 

Will check that out. Thx IF I was to guess the Firebox has never been replaced
and something is clogged up or I guess a bad head gasket might do the same.

Oil level is fine. When you first start the car its loud then quites down a little after a few secs. I took a stethoscope to the engine and it differently sound to be in the cylinder head. Loud and clear from the head and not as clear from the oil pan side. Not sure how the oil pressure is but I guess it could be low enough to cause problems up top and not set off the oil light. Not sure what psi those thing are set to go off on.
Wonder it if be better to get a cylinder head from a junk yard or try to fix this one. Tho I guess you don't know how bad this one is untill you open it up.
Also while I replaced the spark plugs I switched number 3 coil pack with number 2 to see if the missfire would carry over and it did not. Code came back with #2 missfire again.

update:
I did the rubber glove test (or plastic bag and rubber band in my case) and when I first started the car the bag inflated then after about 6-7 sec it sucked in. Rev it up and it still stayed sucked in.

 

Hm I'm not sure about the glove test I'd have to watch the video I don't know about it yet.
It's strange the plugs had no washers, I think what your left with now is simply the cams and the valves and is probably a normal sound from them.

But no, the oil fill cap shouldn't be letting off pressure.

An engine will never be totally silent, and as parts wear there's more play between things like the valves and cam lobes so noises get louder. Sticky valve springs etc etc.

If there is an issue atleast it's the top end. Way easier to fix. Maybe a good cleaning to remove the crud is all it needs now.
To pressurize somethings got to be clogged or restricted I would think.

 

Found this video for testing a stuck valve and the piece of paper I used did the same thing that the paper in the video did with a stuck valve.

Think what I'm going to do first is replace the oring's for the oil sump system along with some engine oil detergent and go from there.

 

That can cause bad flow yeah. Usually you can tell if they're gone by running the car, turn it off check the oil level and if it's foamy/bubbly you got to do all the seals down there, 5 total I think?