The car is a 2007 Grand Prix, with the 3800 N/A. We bought it second hand in 2011 with about 57k kms, now it has about 102k kms.
I used to hear this a while ago, I think even the first winter when we had the car.
Let the car sit overnight, and start it and drive several minutes and at a light at idle, I'll hear three knocks from the engine bay.
Some of the work we did: Change plugs and wires Redid the LIM Ran a few techron tank fuels, Premium fuel. Checked the heat shields, one of them is a little loose PCV changed with new gasket, in 2011 MAF cleaned a few times Coils checked resistance I do have to monitor the oil level every month, sometimes need to add a little, a small cup. After reading on forums, ran Auto RX in the winter time. from November to February. I used to hear the knocks, but at some point hte first knock was louder then the second after were quieter. Then eventually I would stop hearing the knocks.
Currently been using PF47 Ac Delco filter, and Quaker State 5w30 oil.
It was suggested that maybe the piston crowns are dirty due to the short drives, about 2 miles to and back from work. I do try to try on the highway 20 minutes one way several times a week.
I bought MMO, and was about to put it in the crankcase, but didn't and returned it.. Afraid that it might cause more leaks... after reading a fair amount on forums etc... most favour mmo... but looking at how its a solvent I was afraid it would aggravate the Rear main leak that's been going on since we bought the car.
We usually change the oil every 4 months... or 3x a year... regular dino oil...
Should I run another dose of Auto RX, or the maintenance.. safe to use the MMO maybe a week before changing the oil? With the job i have right now I can just about keep the operating costs of the car, as any compression test etc,,, wouldn't be done right away maybe soon...
Loc: Fly Over Region, North America
Could be a timing issue or belt/tensioner. Checked those yet. Also if you have messed with coolant during service you could have a trapped air bubble. You might try the Mos2 or motor oil saver from Liqiumoly, just a thought.
With 60K miles on this 07 engine i am surprised by the rear seal and LIM gaskets. These engines are not known for carbon knock, carbon knock is usually heard at cold start up and sounds almost like a rod knock, it may take 5 min or more to disappear but it does.
From what you describe i think you may be barking up the wrong tree, i don't think its in the engine. Some more information would be helpful.
*Do you any knocking when first started that disappears quickly and is not heard again the remainder of the running cycle? *Have you been using the recommended viscosity since you owned it? *Is this knock sound metallic or more like something moving and clacking like a solenoid? *Any recent Check engine lights? *Is this 3 knocks always 3 or does it vary in amount or frequency? *Does this get louder with lower ambient temperatures? *Do you hear an electric motor noise at start up or shortly thereafter?
ASE L1, Master. Deutsch Meisterbrief.
First of all to BITOG! I honestly have no idea what the knocking noise is, I would however stop putting in oil additives, Techron is ok every now and then in the tank but all these oil additives could be doing more harm than good. If you want a safe and fairly inexpensive way to clean up the engine gently, start using a good synthetic oil like PU, PP, M1 etc.
2012 Honda Accord EX-L K24z3 45,xxx miles PPPP 0w20 / Fram Ultra
2014 VW Jetta SE 1.8T ea888 25,xxx miles Castrol Edge 0w40 / OEM filter
Mice hitting the fan on the way scrambling off the UIM?
May just be accessory belt memory with a quick backslap. TRy a new belt if the current one is ancient - also check that the tensioner is free. I'm really hoping its not coolant pooling in a cylinder, but it sure could be.
I forgot to add that yes we did the Coolant drain and refill. We checked a few times with the bleeder so that there is no air.
As for additives, I've only used the Auto RX, and the Techron.
I haven't really checked the belt/tensioner... thought I do hear a slight rattle or pinging on acceleration at times.. thinking it could be the loose heatsheild..
@Trav, the LIM might have been a bad call.... as it was wet around the area, the RMS leak was there when we bought it, back of oil pan and side wet... valve covers felt dry in the back... and the front
*Do you any knocking when first started that disappears quickly and is not heard again the remainder of the running cycle? - at times a rattle.... at first but don't hear it again.
*Have you been using the recommended viscosity since you owned it?
- yes its the 5w30 with the approved GM standard, 6094.. I think..
*Is this knock sound metallic or more like something moving and clacking like a solenoid?
- sounds metallic, hammering... like a double knock
*Any recent Check engine lights?
- Not yet *Is this 3 knocks always 3 or does it vary in amount or frequency?
- Rarely it varies.... sometimes it sounded faster and usually slower... I'm estimating here, the three knocks lasts about 2 seconds... Not enough time for me to press on the gas to see if its oil pressure related, as a friend suggested...
*Does this get louder with lower ambient temperatures?
- yes in cold weather used to be very loud last year, it is more audible in cold weather and warm weather, even in summer you hear it faintly.. very easy to miss if you're not looking for it... and in the winter if you have the radio on, you'll miss it.
*Do you hear an electric motor noise at start up or shortly thereafter?
Only when driving, after 20 feet I hear what I think is the ABS pump engaging...like a moan...
I'm still a bit stumped why I didn't hear it towards the end of the Auto RX treatment...
I managed to get the service records from the dealer, hard a hard time, and they did oil changes like every year, at about 10k kms...
At times there is a surge at idle, a clunk noise on acceleration, sometimes trouble starting...
Will it make any noise if you start it and just let it warm up or does the car have to be moving? I have heard a noise similar to this which turned out to be a noisy electric AIR pump on a 3800 GM. One that has failed will throw a CEL but the fan inside can wobble when its worn and strike the housing as it winds down to a stop. That would be a heck of a long shot.
ASE L1, Master. Deutsch Meisterbrief.
Thank you again for the input, lol at the song.... I do think I'm SOL..
I have remote started it and let it run for 10-15 minutes from afar didn't hear anything....
Usually happens when the car is stopped, at a red light, or let off the gas and moving.... Could the secondary air pump make that much noise? very audible in colder weather... btw I never knew this system existed.... and I Do hear it on the driver side of the motor... and strange thing when I had my head turned left, I thought I heard the knocking from the back too..... probably looking into it too much...
I'm still at a loss why I didn't hear it after the auto rx was in for a while.... Any way to test the secondary pump?
I don't think its anything to do with the ABS, IIRC there is no mechanical check of the system that would be audible just an electronic check which is complete when the ABS light goes off. AIR pumps can make a lot of noise when worn and it is located on the driver side under the side of the front bumper.
The only cars i can remember that made hydraulic cycling noises was the Citroen's, the old DS, CX and SM cars especially were an orchestra of knocks, clicks and double clicks but nothing like that on US cars.
Testing the AIR pump is easy enough just jump the relay, also check any solenoids in the system as they can make noise also. I don't want to send you down a path with this thought, its a way off guess looking for the obscure nothing more.
You need a second person, start the car cold with the hood open let it run a min or two while you listen then have someone put it in drive and hold the brake (e brake on) and keep listening for a few min.
I cant thing of anything that would give three distinct knocks in this engine internally then stop but externally mounted solenoids and other parts could, it could also be in the transmission but that would be remote. Next time your at the red light where is usually does this put it in neutral and see if there is any difference.
Diagnosing something like this is a difficult enough when you have the car in front of you on a message board its darn near impossible except for endless guessing. I think the ARX is just a coincidence unless it was a lifter or something but that shouod be a noise easy enough to identify.
ASE L1, Master. Deutsch Meisterbrief.
Could it be the knock sensor testing the fuel octane by advancing timing til knock is audible then retarding it?
I'm thinking the engine has significant carbon accumulation in the combustion chambers which is raising compression,so at start up when the ecu isn't reading the o2 sensors the stock timing is too much so once knock is heard timing is adjusted?
Just throwing out ideas.
2006 Charger RT Miles x 2 per oil filter
Could be a possibility just not sure on how to go about testing the knock sensor...
I thought it could be the combustion chamber.. ran BG 44k, once, and the oil level dropped, ran lucas upper lube, and ran the Techron 2 times so far, might do a third soon...
I did read online of a Red Line, additive.. how would that be?
Look at the mds of the products your interested in. There is a product called "guaranteed to pass" with 25-35% amines,so if the redline or techron branded stuff is less concentrated I'd try to find gtp instead. Or double dose weaker stuff. For significant build up 1 tank won't be enough and I'd even consider a piston soak via a vacuum line with mmo or something.
2006 Charger RT Miles x 2 per oil filter
Sounds exactly like the noisy vent valve Saturn VUEs commonly did, but that part is at the rear of the vehicle. Same scenario though, drive off in cooler weather come to a first stop- three knocks. The vent valve circuit being tested. Its supposed to be silent but the valves get noisy after awhile.
Could be some other solenoid underhood like the purge doing the same thing.
I do recall last year, that after I shut the car off while sitting in it for 5 minutes, I heard that double knock while sitting.. sounded in the front as always.
Now with the weather being colder, I shut off the car, I happen to do things near it for a while and hear half a knock to full knock in the back of the car.... and looking up on the web here, other GM's cars with evap knocks... http://www.saturnfans.com/forums/showthread.php?t=112013
Most likely it could be just the evap system, but with knocks like that does the canister have to changed?
Thank you all again for the suggestions, its been very helpful.
Usually check the oil every month, this time went 1.5 months, and itwas about a quart low. One thing is the temperature has warmed up from the - 5 celsuis to about 10 c now.. would the warm weather have burned out all the condensation? I try to drive it at least 5 kms one way.. to warm it up....
I don't do much mileage and just surprised it would do that.
thank you Ducked, is this the procedure of spraying mist water in the intake? I'm not comfy trying that out yet.... any other addivites, that worked for you?
Never tried anything else that worked. In my implementation, I ran an IV line into one of the (many) rubber tubes hanging off the (mid-80's) carburettor that saw intake manifold vacuum. If I did (or do) it again I'll try and arrange misting or suction into the air intake.
Other improvised solutions I've heard of include:-
(a) Brake fluid dropped onto the piston crown though the plug hole (theory being that its a powerful solvent, eg for paint - suppose you could apply other solvents in the same way)
(b) A grain or few of rice, ditto (theory being that they rattle around for a while, dislodging carbon, and then they burn off - I got a similar but more drastic effect with a broken bit of piston ring;no remaining carbon but lots of little dings in the piston crown and the plug side-electrode flattened)
Water seems less likely to be damaging than either of those. Dunno about commercial products. I used something called Redex (UK market) sometime in the 80's. Didn't seem to do anything.
Nice things about water: Cheap, Open-source formulation, fairly fully-understood mechanism of action, low toxicity, No abrasive residue (assumes distilled water. I was using aircon condensate which should be close. Scottish tap water is probably mostly close enough too).
Spraying water in by hand is likely to take a tediously long time though.