2000 Silverado 4.8 that has a constant low RPM noise that at first thought was coming from the dashboard, like a heater fan bearing going bad. Started at 1,500 miles and has contiued since (7,500 at present). Can only hear it atapprox. 750 to 1,000 rpm and it does not change with engine RPM or fan speed. Even pulled the fan fuse. Dealer told me it was coming from the plenum. The noise seems to come from the plenum between the air box and intake manifold. Has anyone had this problem and solved it by adding a performance air intake system???
I'm a week late in posting the results of the dealer's latest efforts, so here goes:
After four days in the shop, the service advisor said two aircheck valves had been replaced. The service report said two smog pumps were replaced. I didn't even know there were two smog pumps on the truck. They also performed the 6000 mile service- change oil, rotate tires. They also reprogrammed the PCM for harsh 1-2 shifts and it does shift easier. I had noticed a thumping while coming to a stop, and sure enough, the outside edge of both front tires were feathered due to misalignment of 1/10th of a degree. The hits just keep on commin'.
Back to the ping, the tech believed the noise was exhaust related, because the spark advance was retarding during a test drive, and it was a little difficult to reproduce the ping at the local road speeds and conditions. Now, I've babyed this truck since I bought it in order to break it in and keep ping to a minimum, but since this last service escapade I've been more aggressive on trying to induce ping on demand. I pulled a local hill with a decent grade and to my amazement (!!!!) discovered the ping will disappear for about a second upon hitting a bump in the road. Sounds like a ground problem.
I noticed on a bottle of Marvel Mystery oil (gas treatment formula) that it would reduce carbon build up and do other ping related things. The Techron also said something about reducing buildup.
Has anyone used Marvel gas treatment in an attempt to reduce the carbon....
Same question for Techron.....
If not, I'm about to conduct an experiment using both (not at same time). I'll run about 3 tanks with each and see if anything changes.
priced at 2/$5.99 at Costco. Rather than buying for $9.99 ea. at a Chevron station. Only thing I noticed when using it was that it minimized hesitation. Not sure on the knock issue as I've not had it nor did it cause any after using. I would say that the engine had an overall cleaner sound but that doesn't really make any sense...LOL!!
I used the Marvel oil (gas treatment) first....I'll see if I notice any difference....
Another question...... let's say that this carbon build up thing is right, or it does exist. When the chemicals are used (whatever type is used), what happens to the carbon. Where does it go? I understand if the head is taken off it can be sucked out, but that's not possible in my case unless the dealer does it.
I would venture to guess carbon deposits cleaned with the Techron treatment would mostly be removed in the fluid, just like washing dishes. With the Marvel oil treatment the deposits would mix with the engine oil and settle in the oil pan with some possibly blown out of the exhaust. Again, I'm no expert. Quadrunner500 or some of the people on this board are are better qualified to answer you question.
Mr. Rogerz: The engine is 4.8....miles 27600. Also, the Marvel Mystery Oil I added was not the regular stuff. It was "gas treatment" formula. It was next to the Chevron Techron on the counter. The bottles basically said the same thing.
I'll probably switch to the Chevron stuff after a couple of tanks.
Obyone: Thanks for info.....
How about using Chevron, etc. about every 3000 miles like bottle says.....think that's good idea, or waste of money. By-the-way,,,, I use the cheap gas.
have a silverado that does not ping at all? I am wondering if it is fixable or just a characteristic of the motor? Has anyone totally fixed the problem with a combo of new plugs and a cooler thermostat? How much does the thermostat help? Also, does anyone know if the problem has been solved for the 2001 model year?
and no ping. Only thing is...my 5.3 never pinged from day one. The bearing clearances has been reduced for '01 ending the knock on startup. Not sure on the ping though.
has pinged since about 2000 miles when I first noticed it. It's now just over 6000 miles. This morning I put it in the shop for the fourth time for this problem . GM has offered to extend my 75000 mile warranty to 100000 plus a rental car. Roger
Sorry for post being without enough information. My 4 year old daughter has taken an interest in the internet (trucks) and is usally here with me when I'm trying to post/type.
Dear old mother's been gone awhile, but she ALWAYS babied her car. So it was no surprise when I would jump in, punch it, stand on the throttle, keep it pinned as it shrieked up the street, there would be a cloud of black smoke in its wake. Do that a few more times and no more black smoke. Used to call it "blowing out the carbon." Interesting though, never pinged before or after.
Now we are to believe that carbon buildup is the culprit, causing the ping some have experienced. Also funny how I drive like my mother used to, now that I pay the bills. So when today, in a rare moment, I punched it, stood on the throttle, kept it pinned as it shrieked up the street.....NO black exhaust.
Where is all that carbon? Think about this. Carbon buildup has always been normal, ping has not. Tighter emissions and fuel efficiency have all but done away with "blowing out the carbon." Ping was always solved by retarding the ignition timing, richening the mixture, using higher octane, or some combination.
When someone with ping can reliably post a satisfactory conclusion to their problem that resulted from soaking the combustion chamber overnight with solvent, I'll be very interested. Until then, you'll forgive me if I remain skeptical.
Understood...LOL!! I wouldn't do it too often. I will usually do it anywhere from 9-12,000 miles. Not too sure how well it works. I can remember one time when it did work. I had an '83 Toyota Corolla as a junker. Ran the car since new for 15 years and it was sluggish. Used the Chevron cleaner and acceleration was increased by at least 50%. Of course, that was with 15 years of buildup and one bottle of Chevron magic stuff. I then removed the catalytic converter and the car felt like new...actually felt waaay better than new as I figured the converter was clogged too.
My 00 pings a little, only at very light throttle, say about 30mph on a level road. I went form Sunoco "regular" 87 octane, and at the half tank level filled it with "Ultra 94", so it ended up being about 90 octane mixed up. I noticed the difference almost as soon as the truck ran a few minutes, it was a lot smoother running, and I couldn't get it to ping. I went over the steepest grade in town last night, and it didn't ping at all, even when I really tried to make it do it by very slowly applying the throttle while slowly climbing. I guess I'll try the Techron stuff and see if that lets me use the cheap gas. I still don't see how there can be carbon in a truck with 6500 miles on it, and when the tailpie is still almost clean inside! it must run really lean to keep it that clean..I think the plug/stat deal is the real cure... And I'll punch it 20 times a day!!!!30 if I "have " to !!!!
Man you guys are on the ball! Thanks for the information.......... Listen to this.....
As you probably all know, I filed a case on the knock on my truck with GM. The knock is coming from the lower end of the motor and it sounds louder on the driver's side. The sound is always there on fresh starts. However, it goes away when the engine gets hot. Carbon or lower end bearings?
Anyway, I called GM today to remind them that I was still waiting. The operator informed me:
1. take my truck to the dealer and they would "flush" the motor to clear out the carbon. It would have to sit overnight. I thought he said there was a TSB now for carbon buildup, but I'm not sure.
2. Start using Synthetic oil ASAP.
My response was...."what the hell you talking about!" "use synthetic oil" Who's going to pay for that? (I didn't tell him I was already using synthetic oil and it did not help the knock).
Here's my questions for you guys.....I need quick because I'm suppose to take my truck in for this "blow out" Monday:
1. Why wouldn't regular use of Chevron Techron clean out the carbon?
2. Where should I be hearing the knock for it to be carbon buildup?
3. On this blow out, will any of the blown stuff end up in my pan or other places (obyone answered this for me already, I think)? and does this blow out thing hurt the motor?
4. From what I described above (heated engine--not knocking), does that sound like carbon buildup?
5. If the problem is carbon, shouldn't the carbon return in 15k miles or so?
Knock on startup is not carbon related. GM discontinued their ever so popular knock on start up by tightening tolerances on crankshaft main bearing clearance.
The constant pinging I would think is more programming related than carbon buildup. The trucks are programmed to run lean in order to increase mpg at the expense of the long term longevity of the motor.
If you really wanted to resolve this issue....ask for a 2001 5.3l motor replacement. The example is that Ford replaces their slappin motor so shouldn't GM do the same? If you decide to pursue this angle, please let me know how you fair...
you could just ask the service manager straight out if he would consider an engine swap to correct the knock on startup and see what he says after he recovers from the shock of the question.
1.) Would seem like it should. 2.) Bottom end knock on startup is not same as ping. Ping is heard under light acceleration at low rpms, ie lugging the engine. 3.) Blows out the exhaust ports into the catalytic converter, and then hopefully out the tailpipe, and not plugging the cat. 4.) Doesn't sound like carbon buildup to me. Try stepping up from 5W-30 Mobil 1 to 10W-30 M1 for the cold start knock. 5.) Good question. I think it would return. That's why I'm doubtful a solvent scrubbing is going to be a permanent solution.
Next to retarding the ignition timing (which you can't do) the best fix has been to modify the thermostat so it opens sooner. If interested in how to do this I can post.
Thanks guys for fast reply....let me better define this knocking.....I just tested/started the truck a few minutes ago and here's what happened....
Temp. here is about 70 deg....F
Started the truck and it did not knock at all. After warming for about 5 minutes, I drove about 1 mile (low speed) and stopped. It was then knocking. After I let it idle for a few minutes, it slowly dissipated but did not stop completely. I drove it back home and let it idle again. The noise/knocking was gone.
I know this sounds crazy, but it usually knocks upon a fresh start. On this occasion, it did not knock until I drove it for a mile.
quadrunner: The knocking sound I have is not pinging. I once had a pinging car that ping at the top end. It sounds kinda like a diesel enging but not that loud. The noise is coming from mid to lower end of motor (not the top at all). It sounds more like a racket/bearings/ or shaft action. Maybe a revolving sound?
It does not do it all the time. It doesn't do it at all when the motor is hot. In the case of carbon buildup, would a hot engine retard the carbon knock, or would it matter?
Sorry my description is not better, but I'm doing the best I can do.
Monday night a buddy called. Seems he started his 94 'rado up and got a hard knock out of the 350. Engine was already warm, and had not made so much as a tick up to now. Using the tried and true dowel stick to the ear, I isolated the noise to the cylinder of #2. Yes, good maint. and oil. Ran the engine gently up to 1500rpm and listened very carefully. Knock slowly got quieter and the engine smoothed out. Then the knock disappeared and has not come back. Added a pint of Marvel to the full tank of gas and told him to get the thing out on the road occasionally. Hot or cold start, the knock is gone. It does sound scary when a chunk of carbon breaks loose from the head and starts bouncing around in there!
for a thermostat, isn't it? I saw that the earlier models are a lot cheaper, but that the new ones include a housing. Is the housing required for the new body styles? Oh yeah, thanks for the links!
I don't like what you describe. I would get GM involved right away, and stay on it. It sounds like the bottom end, not spark, timing, carbon, or ping related.
Only thing I would suggest is try to see if a switch from 5W to 10W motor oil makes any difference. If bottom end clearances are excessive, this might quiet it down somewhat. Even if it did, I would still want GM involved right now.
I am also convinced that my 4.8l is not carbon related. It's more of lower end chatter. The bearings or something is making the noise (in my opinion).
Anyway, I'm taking the truck to the dealer Monday for the carbon cleanout since that's what GM told me to do. We'll see if that has any change.
You can bet that I'll stay on GM.....they should know that from my last contact with my 00 model. I'll post the results Tuesday night if they're done with it by then.
Well, nothing has been resolved from the dealer as to what is causing the pinging or resonation. I went for a ride up the steepest grade in town with the service manager in tow, and his spin was the changed piston firing order, and referred to a service bulletin advising against tearing down or replacing motors for this problem. He will send me a copy. So GM is aware of this particular noise. The tech guessed exhaust resonation. Hmmmm. The PCM shows no error codes, and the knock sensors and air idle control valves have been replaced. Plus, overnight engine soaking with Techron.
The service manager was "100% certain it's not ping", and guaranteed if anything happened to the engine down the road he would gladly replace it. The only problem is, they can't positively identify and eliminate this noise which we could not duplicate on another brand new Z71 Silverado in their lot. He promised they would further investigate and on another truck that pings to try and come up with a solution. Interestingly, the rental 'rado I drove had the identical noise under the same driving conditions.
z71, 160 degree thermostats are not recommended for the new rados. The dealer gave me a $1500 horror story about one that they would not cover under warranty because of one. Cats, injectors etc. Also, My dyno guy will put in a 180, but not 160 thermostat, that should be in combination with the Hypertech III.
There are a few different noises on this topic, and I'm thankful we have a place to sort these issues out. Thanks, Roger
the HPIII unit doesn't have a programming setting for it but has one for the 160....another thing, the 180 stat runs close to the stock stat rendering the unit useless...
your service manager is full of sh*t. Has your service manager ever heard of the Magnuson-Moss Act? You should print a copy and hand it to this smuck...
These service managers, shop foremen, service advisors, and techs sure piss me off when they get on their soapbox and start preaching about warranty. They should read this act and what it says about deceptive warranty practices which they are so good at performing....NOW if they could only repair a vehicle as well as they spit out their propaganda....
At minimum, you should get and extended warranty for 6/100 at the expense of GM and your friendly GM service manager. Jed1894 could help you with this issue. The excuse that they "all do that" doesn't make it right. Ask Firestone about that....
I hate to agree, but how can the service advisor be 100% sure it's not ping if they can't identify what it is? Yet at the same time they refer to a service advisory that infers they know about the problem, and what NOT to do? This is contradictory. And what's the point of telling you the thermostat horror account, and that they will fix anything down the road, if not to persuade you to GO AWAY NOW, and live with the problem. That's the objection I have. They recommended a Techron solvent soaking before, which didn't work. That's never been how you solved ping in the past. They may be selling new ideas now, but I'm not buying! Good luck Rog.
Comments
Its amazing this multiple personalities disease and how it effects people
Ryan
Dealer told me it was coming from the plenum. The noise seems to come from the plenum between the air box and intake manifold. Has anyone had this problem and solved it by adding a performance air intake system???
Ryan
Ryan
After four days in the shop, the service advisor said two aircheck valves had been replaced. The service report said two smog pumps were replaced. I didn't even know there were two smog pumps on the truck. They also performed the 6000 mile service- change oil, rotate tires. They also reprogrammed the PCM for harsh 1-2 shifts and it does shift easier. I had noticed a thumping while coming to a stop, and sure enough, the outside edge of both front tires were feathered due to misalignment of 1/10th of a degree. The hits just keep on commin'.
Back to the ping, the tech believed the noise was exhaust related, because the spark advance was retarding during a test drive, and it was a little difficult to reproduce the ping at the local road speeds and conditions. Now, I've babyed this truck since I bought it in order to break it in and keep ping to a minimum, but since this last service escapade I've been more aggressive on trying to induce ping on demand. I pulled a local hill with a decent grade and to my amazement (!!!!) discovered the ping will disappear for about a second upon hitting a bump in the road. Sounds like a ground problem.
So, back into the shop it goes Monday morning.
Film and popcorn at 11. Roger
Has anyone used Marvel gas treatment in an attempt to reduce the carbon....
Same question for Techron.....
If not, I'm about to conduct an experiment using both (not at same time). I'll run about 3 tanks with each and see if anything changes.
Tell me if I'm wasting my time and money!
Thanks John (clueless)
Dean
Another question...... let's say that this carbon build up thing is right, or it does exist. When the chemicals are used (whatever type is used), what happens to the carbon. Where does it go? I understand if the head is taken off it can be sucked out, but that's not possible in my case unless the dealer does it.
John
Also, which engine are we talking about? Miles?
The engine is 4.8....miles 27600. Also, the Marvel Mystery Oil I added was not the regular stuff. It was "gas treatment" formula. It was next to the Chevron Techron on the counter. The bottles basically said the same thing.
I'll probably switch to the Chevron stuff after a couple of tanks.
Obyone:
Thanks for info.....
How about using Chevron, etc. about every 3000 miles like bottle says.....think that's good idea, or waste of money. By-the-way,,,, I use the cheap gas.
Thanks John
Ryan
Peter
John
At least she likes trucks now.....not boys!
John
Now we are to believe that carbon buildup is the culprit, causing the ping some have experienced. Also funny how I drive like my mother used to, now that I pay the bills. So when today, in a rare moment, I punched it, stood on the throttle, kept it pinned as it shrieked up the street.....NO black exhaust.
Where is all that carbon? Think about this. Carbon buildup has always been normal, ping has not. Tighter emissions and fuel efficiency have all but done away with "blowing out the carbon." Ping was always solved by retarding the ignition timing, richening the mixture, using higher octane, or some combination.
When someone with ping can reliably post a satisfactory conclusion to their problem that resulted from soaking the combustion chamber overnight with solvent, I'll be very interested. Until then, you'll forgive me if I remain skeptical.
Have you punched your throttle lately?
Ryan
I guess I'll try the Techron stuff and see if that lets me use the cheap gas. I still don't see how there can be carbon in a truck with 6500 miles on it, and when the tailpie is still almost clean inside! it must run really lean to keep it that clean..I think the plug/stat deal is the real cure...
And I'll punch it 20 times a day!!!!30 if I "have " to !!!!
As you probably all know, I filed a case on the knock on my truck with GM. The knock is coming from the lower end of the motor and it sounds louder on the driver's side. The sound is always there on fresh starts. However, it goes away when the engine gets hot. Carbon or lower end bearings?
Anyway, I called GM today to remind them that I was still waiting. The operator informed me:
1. take my truck to the dealer and they would "flush" the motor to clear out the carbon. It would have to sit overnight. I thought he said there was a TSB now for carbon buildup, but I'm not sure.
2. Start using Synthetic oil ASAP.
My response was...."what the hell you talking about!" "use synthetic oil" Who's going to pay for that? (I didn't tell him I was already using synthetic oil and it did not help the knock).
Here's my questions for you guys.....I need quick because I'm suppose to take my truck in for this "blow out" Monday:
1. Why wouldn't regular use of Chevron Techron clean out the carbon?
2. Where should I be hearing the knock for it to be carbon buildup?
3. On this blow out, will any of the blown stuff end up in my pan or other places (obyone answered this for me already, I think)? and does this blow out thing hurt the motor?
4. From what I described above (heated engine--not knocking), does that sound like carbon buildup?
5. If the problem is carbon, shouldn't the carbon return in 15k miles or so?
Thanks in advance for help......
John
1999 Chev. Silverado 4x4, ext. cab. 4.8L, 27,800 miles. Mobil 1 since 26,300 (give or take a hundred miles or so).
John
The constant pinging I would think is more programming related than carbon buildup. The trucks are programmed to run lean in order to increase mpg at the expense of the long term longevity of the motor.
If you really wanted to resolve this issue....ask for a 2001 5.3l motor replacement. The example is that Ford replaces their slappin motor so shouldn't GM do the same? If you decide to pursue this angle, please let me know how you fair...
Dean
2.) Bottom end knock on startup is not same as ping. Ping is heard under light acceleration at low rpms, ie lugging the engine.
3.) Blows out the exhaust ports into the catalytic converter, and then hopefully out the tailpipe, and not plugging the cat.
4.) Doesn't sound like carbon buildup to me. Try stepping up from 5W-30 Mobil 1 to 10W-30 M1 for the cold start knock.
5.) Good question. I think it would return. That's why I'm doubtful a solvent scrubbing is going to be a permanent solution.
Next to retarding the ignition timing (which you can't do) the best fix has been to modify the thermostat so it opens sooner. If interested in how to do this I can post.
Agree with Obyone above.
Temp. here is about 70 deg....F
Started the truck and it did not knock at all. After warming for about 5 minutes, I drove about 1 mile (low speed) and stopped. It was then knocking. After I let it idle for a few minutes, it slowly dissipated but did not stop completely. I drove it back home and let it idle again. The noise/knocking was gone.
I know this sounds crazy, but it usually knocks upon a fresh start. On this occasion, it did not knock until I drove it for a mile.
quadrunner:
The knocking sound I have is not pinging. I once had a pinging car that ping at the top end. It sounds kinda like a diesel enging but not that loud. The noise is coming from mid to lower end of motor (not the top at all). It sounds more like a racket/bearings/ or shaft action. Maybe a revolving sound?
It does not do it all the time. It doesn't do it at all when the motor is hot. In the case of carbon buildup, would a hot engine retard the carbon knock, or would it matter?
Sorry my description is not better, but I'm doing the best I can do.
Thanks again.....
John
http://www.thunderracing.com/truckcatalog.htm
Headlight controller
http://www.truckautoaccessories.com/acb/showdetl.cfm?&DID=9&Product_ID=11&CATID=6
Hot or cold start, the knock is gone. It does sound scary when a chunk of carbon breaks loose from the head and starts bouncing around in there!
Only thing I would suggest is try to see if a switch from 5W to 10W motor oil makes any difference. If bottom end clearances are excessive, this might quiet it down somewhat. Even if it did, I would still want GM involved right now.
Can't make it ping at any speed.
I am also convinced that my 4.8l is not carbon related. It's more of lower end chatter. The bearings or something is making the noise (in my opinion).
Anyway, I'm taking the truck to the dealer Monday for the carbon cleanout since that's what GM told me to do. We'll see if that has any change.
You can bet that I'll stay on GM.....they should know that from my last contact with my 00 model. I'll post the results Tuesday night if they're done with it by then.
Thanks....
John
The service manager was "100% certain it's not ping", and guaranteed if anything happened to the engine down the road he would gladly replace it. The only problem is, they can't positively identify and eliminate this noise which we could not duplicate on another brand new Z71 Silverado in their lot. He promised they would further investigate and on another truck that pings to try and come up with a solution. Interestingly, the rental 'rado I drove had the identical noise under the same driving conditions.
z71, 160 degree thermostats are not recommended for the new rados. The dealer gave me a $1500 horror story about one that they would not cover under warranty because of one. Cats, injectors etc. Also, My dyno guy will put in a 180, but not 160 thermostat, that should be in combination with the Hypertech III.
There are a few different noises on this topic, and I'm thankful we have a place to sort these issues out. Thanks, Roger
http://autopedia.com/html/HotLinks_LemonMM.html
These service managers, shop foremen, service advisors, and techs sure piss me off when they get on their soapbox and start preaching about warranty. They should read this act and what it says about deceptive warranty practices which they are so good at performing....NOW if they could only repair a vehicle as well as they spit out their propaganda....
Good luck Rog.