I'm a car noob, and have never heard "knock" before, but I would guess this is it. I'm scared to death its something serious. Here's my story:
Filled up with gas at 4:30pm at SpeedWay. Drove about 1.5 hours from Lansing to Mt Pleasant doing about 90 or so MPH (so 4k rpm's steady the whole way). Stop and eat at Bennigans. Start driving north again for 1.5 more hours until I get to Gaylord. Stoping at the stop sign at the end of hte off-ramp, I let the RPM's drop to idle and there is a LOUD ticking/knocking noise from my engine bay, I mean it sounds REALLY bad. But the engine feels fine to drive. No loss of power, and the ticking/knocking goes away above 2500 RPM's, it completely smooths out and sounds perfect.
Anyway, I'm freaking. So I get it up to Boyne Mountain, about 15 minutes later, and turn the car off for a few seconds while I run in to take a piss, and look under the hood. Everything passes visual inspection, oil level normal. Start the car up, and now it only knocks/ticks below 2000 RPM. Ok, so I need to get home, and at highway speeds RPM's are above 2000 anyway, so I figure I'll be fine. I get it home, turn the engine off, go inside, go back outside, start her up, and now she only does it below 1700 RPM. wtf?
I tried listening to where the knock is coming from, seems to be under the front valve cover from best I can tell, its just so freakin loud.
Guys, I'm a noob, have no idea what this could be, and I'm scared sh!tless its a spun bearing or something. I really don't want to dump a grand or more into this engine, I was hoping it'd last another year or two before I have to do that... What could this be?
Isnt there anyway you can copy the noise and then post a link to it?
Ticking doesnt really mean to much, could be anything, bearings,lifters, anything.
my car makes a knocking sound during low RPM, think its just because of the hydrolic valve lifters and stuff... but mine is only when cold
Well I've always had a very faint ticking noise, but this time its just scary how loud it is. I mean, you almost don't want to stand near the engine its so loud.
I'll see if I can't get a sound sample later today for you.
Do you think it's safe to drive? I have to make a 100mile trip today
In my opinion I dont see why you couldnt drive it. I know someone who had lifter nosie and they drove it, just got louder by a bit.
Its up to you man.
I had similar ticking, first it was from 2k up to 4k but it would switch around a bit sometimes. Starting at 3 instead of two etc. I'd heard knocks before but I didn't think that's what it was. Ended up being totally fried bearings and a bad valvespring, not sure which was actually clicking. Mine took 4 months before it gave out so even if that's what it was you might be ok to drive. I wouldn't, and if you do be very gentle until you know for sure.
Just a thought, has your engine got good clean oil of the right grade and up to the correct level, possibly this noise is dut to an hydraulic lifter blockage, they have very small oil passages that can clog if the oil bacomes dirty.
If you put the handle of a screwdriver against your ear and touch the buisness end on various parts of your engine in the general area of the noise, you should be able to narrow down where the noise is coming from, this may give some clues, please be careful to avoid rotating parts with hair clothing etc and spark plugs/wires with metal objects, we dont want to add any more noises
Good luck
James
Well, its gone (!?!?!?!?). Maybe bad gas? After filling up again today at Mobil with good old 93 octane, drove it to Alpena and back (about 220 miles round trip) and well, its gone. No more knock.
I did get this sound clip of it this morning before it went away. Sorry for poor quality, it was taken with an MP3 player from my drivers window:
click me
Note how it smooths out above about 1100 RPM this morning. Each time I turned off the car, it would only make the noise at a lower RPM.
I am running a superchip which advances my timing, so I'm assuming poor gas would probably cause it. Sound right?
EDIT: It does, however, still idle like crap. Not a strange noise, but it sits there and stumbles all over the place. Could the bad knock have maybe fouled a plug (I don't know what that means, but seems like it would cause bad idle)?
Well, its back. Filled up at a different Mobil station today though. But the loud knock is bad at low RPM's. What gives?
I have a CEL, its the usual "IMRC stuck open" so I have a new IMRC ready to go in to replace it, but I've had that CEL for a month or so now and am just now getting this knock.
Should I ditch my Bosch +4 plugs too for some autolites?
I'm really lost, my car sounds like crap. What would cause this knock?
Ok hereā??s your problem.
Your car has been feed a steady diet of 93 octane gas which combined with short trips has lead to carbon build up. This explains your bad idle and your knocking noise after your long trip.
What you experiencing is a ā??carbon ringā? at the top of one (or more) of your cylinders. It was formed after your long drive at high speed. When you shut your engine down the carbon broke loose and got trapped in the top of the cylinder at restart. When the piston hits the ring it makes a sound like a bad rod bearing. At higher RPMs the sound is masked so you donā??t here it as much.
How to fix it.
1) Use the correct octane (for a standard compression contour thatā??s 87).
2) Have the engine de carbonized at a shop with the correct equipment.
Remember this simple rule high octane gas is for high compression engines. You are getting lees performance and spending more money using so-called ā??high testā?. The ā??high testā? gas will not burn at a high enough temperature in a standard engine to burn completely, leaving behind the carbon that is causing your problems.
jeff
Originally posted by rkneeshaw:
Well, its gone (!?!?!?!?). Maybe bad gas? After filling up again today at Mobil with good old 93 octane, drove it to Alpena and back (about 220 miles round trip) and well, its gone. No more knock.
I did get this sound clip of it this morning before it went away. Sorry for poor quality, it was taken with an MP3 player from my drivers window:
click me
Note how it smooths out above about 1100 RPM this morning. Each time I turned off the car, it would only make the noise at a lower RPM.
I am running a superchip which advances my timing, so I'm assuming poor gas would probably cause it. Sound right?
EDIT: It does, however, still idle like crap. Not a strange noise, but it sits there and stumbles all over the place. Could the bad knock have maybe fouled a plug (I don't know what that means, but seems like it would cause bad idle)?
Thats what I call major knocking, mine is very quiet, its probaly because of the timing belt cover too... 
Are 20 mile drives to and from work considered short drives? Whats wierd too is my trip to Alpena? Well, it definately wansn't a normal trip. I'll just say the normal drive time is 2 hours, I was there in 1 hour 7 minutes :P What can I say, the road was empty. Anyway, the car ran at steady high RPM's for awhile then too, but went away. Now after I posted its back, its gone again (the knock that is) but it still idles really rough, I mean I feel the vibration of the engine in my seat now at idle.
Should I be checking simple things like plugs and wires first? de-carbonizing the engine sounds $$$$ since I'm sure they have to pull the heads off, at least thats what I'm assuming.
I do have to install the new IMRC, replace the sticking IAC, and clean my intake manifolds again, and I think I'm going to switch to Autolites anway. Think its worth a shot?
I just dumped a buttload of money into the trans, and the engine has always ran well, until BAM, this happens this weekend out of the blue.
Also wanted to mention the car is driven at between 75-80 on a daily basis on my 20 mile drive to work in the morning, and on the 20 miles return trip home (all highway). So the 90 MPH cruise downstate wasn't TOO out of the norm.
No itā??s not too expensive and it is similar to a fuel injector cleaning, basically itā??s a chemical treatment, via the intake manifold. I would guess $100 depending one who does it.
You should check the basics, a cracked plug, coil pack or bad wire will cause a ticking sound and sometimes a genuine Knock at idle.
Was the car always driven on long trips? Or is this something new?
And remember, over octane=carbon=degraded performance.
jeff
A cheap way to de-carbon the engine is to get a spray bottle of water, and spray it into the throttle body with the engine running. This causes enough of a temperature change to cause the carbon to 'come off' for lack of a better term, of the engine parts. I haven't used this method, but am told it works. I watched a Tech at work decarbon a Mustang using one of those chemical treatments, the knock this car had before the treatment was horrible, it sounded like it was going to fall apart. After a few minutes of high-revving, and white smoke coming out the exhaust, the engine ran like new. No more knock, and it idled smoother. I would suggest either having the engine professionaly decarboned, (de-car-boned?) lol..or try the water mist method.
Originally posted by mercman:
Was the car always driven on long trips? Or is this something new?
And remember, over octane=carbon=degraded performance.
It always sees alot of highway miles. There's the 40 mile round trip drive to and from work every weekday, then at least maybe 4-5 500 mile round trips downstate a year. There's not much mileage this car has seen that is stop-n-go city driving. But I'm passing cars enough to keep the RPM's always going up and down 
I do run a SuperChip that requires a higher octane fuel because it adjusts spark timing. I also thought the higher octane not only makes the car "peppier" but also burns cleaner? no?
Originally posted by tastethefury:
After a few minutes of high-revving, and white smoke coming out the exhaust, the engine ran like new.
Well first the water mist thing just sounds scary. I was under the impression water and engines don't mix 
But anyway, this sounds just like when you spray some carb cleaner in through the TB when the car is running.... Is de-carbonizing as easy as that?
Shoot, I can spray a few cans of TB cleaner through the TB while its running if that'll help... Remember too though that I've regularly cleaned my intake manifolds (I realize thats not the cylenders) and run a bottle of injector cleaner through the system every 4000 miles or so. Woudlnt' that help prevent carbon buildup?
Well I work with a mechanic here and he heard your sound clip and said that it is probably knock.He did also say that you could have carbon build up and that yes the water trick down the throttle body will work or intake cleaner just remember if you do either change your plugs after because they will be full of crap
It's too fast and irregular for rod knock, from what I can make out from my seat here in my cube. I would say that Mercman's diagnosis may be spot on. In any case it wouldn't hurt to run some MOPAR Combustion Chamber Cleaner through it, which runs about $5 a can from your local Chrysler dealer. It does exactly what mercman described. It breaks up the carbon in your engine and shoots it out the exhaust.
The only variation I take from the instruction on the can are to let the car sit a least a few hours once the inter contents are emptied into the engine, to really let it do it's work. Then when you start her up you'll sweat your car was on old diesel train by the amount of smoke and noxious crap that come out the exhaust. Great for redusing the mosquito population in your area (not so great for the ozone layer!).
Ryan, call me if you have questions.
My preferred method of using those types of cleaners are to use the liquid version, hook them up to a vacuum port and slowly meter the contents into the motor. Let about half of it in, keeping the revs up a bit to keep the motor running. At about half a can let the revs fall and it'll stall. Let the stuff that's trapped in the engine soak for a few hours and then re-start the motor and run the remainder of the cleaner through it. Change your oil after you're done to get the solvents from the cleaner out of your crankcase. Pulling and cleaning the plugs after isn't a bad idea either, though an old-fashioned Italian tuneup would probably be sufficient to clear them of any junk from this procedure.
Good luck,
Scott
Cool, good info. I've done some searching around and found
this page. Anyone heard or used that BG 44k stuff?
I also found
these instructions for the MOPAR CCC. Sound about right?
I plan on picking up about two cans (probalby only use one) of the MOPAR shiz, and a new set of Autolite douple-plat spark plugs and give my whole intake an overhaul this weekend, if I don't have stazi install my camber plates.
Well she's soaking in the MOPAR Combustion Chamber Cleaner at the moment, then its a 20 minute drive to Gaylord for new Autolite plugs. I'll rag on her a bit on the way, as per the instructions I found and hopefully this cleans her out good.
I only used one can, but bought two so if I wanted/needed, could do a second treatment.
And my hands stink like chemicals, so I have to get out of this office before I get high.
Well, just beat the sh!t out of er, and she seems to be a little smoother now, but still vibrates the car at idle (only below 800 RPMs). So, on to the intake overhaul procedures!! And spark plug change. I'm gonna smooth this sucker out sooner or later.....
well if oil passages do become dirty, what do you do to clean them out. My car started knocking just a few days ago and even stalled on me on the free way. I 've been told that I am gonna have to replace the engine, but I wanty make sure that it isn't a simpler problem.
Well, about 2 weeks later and my car no longer runs, so take that for what its worth.
3L time.