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Explorer motor rattle

jcasperjcasper Posts: 37
edited March 2014 in Ford
I own a 99 Ford Explorer that has a rattle in the motor. It has the old style push rod 4.0L V6. It is noticeable at an idle, and also on the freeway, at times can be really loud. when on the freeway the noise sounds like a pinging sound (usually caused by to low of octane gas). I have been told by the dealer that this noise is carbon knock and is caused by carbon build up in the combustion chamber. They have no solution to the problem except to decarbon the combustion chamber which is only a temporary fix. I have had another mechanic clean the MAF sensor and that has not helped either. The Dealer has shown me a TSB from ford saying that this motor must be run over 3000 RPM everyday to keep this from happening. Running the motor over that is definetley not a problem for me. I would appreciate any help I can get.


  • desi501desi501 Posts: 66
    There are ways to get rid of carbon and once it's gone, you'll be clean for a long time. They make some decarboning chemicals to pour into the carb but I generally use small amounts of water. You have to be VERY CAREFUL when doing this. Too much water can lock up the engine and cause severe damage. At 3000 RPM very slowly drip small amounts of water down the carb. Using some trans oil or other decarboning chemical first until the engine stalls would be helpful to loosen it. Let it soak in for 10-15 minutes before the water treatment.
  • vidtechvidtech Posts: 212
    try using delco can get it at GM dealerships.i have used it for years to clean combustion chambers and works quite well.
  • Find an independent shop or dealer (many Toyota, Lexus, Infiniti) that uses BG products ( I had my '94 Explorer done for the same pinging reason. Cost about $100 and truck ran GREAT after and no more ping. Started using BG 44K 2-3 times a year in my other cars. Noticeable improvement in power and mileage.
  • how do you propose pouring water into a carb on a '99 fuel injected engine?
  • jcasperjcasper Posts: 37
    The Ford dealership has run some ford decarbon chemical through the motor followed by some water. That helped for a short time but it always returns. Is this something I am going to have to do on a normal basis or is there a permanent fix. On the intake manifold there is a vacuum hose that you can suck the chemical through, so that takes care of my problem of not having a carb to pour it through. Do auto parts stores carry this BG 44K or do I need to get it from the website. Thanks everybody for your help and I appreciate any more input.
  • would changing brands of gasoline help?
  • vidtechvidtech Posts: 212
    you can introduce water or cleaners into the throttle body or pcv vacuum line.or the pro's connect to the fuel rail itself.
  • swschradswschrad Posts: 2,171
    assuming your manual says 87 octane, don't use anything higher. you don't get smoother response, advanced cleaning, whites whiter-than-white, or a fresh lemony scent. what you get if you put in more octane than the car was designed to run on... is... more carbon deposits!

    not what you want. use the recommended octane. brand to brand, the only major difference comes from those refineries that have already overhauled to meet the 2006 EPA no-sulfur requirements. sulfur and carbon are both elements, and sulfur from ClogCo gas is not going to turn into carbon. not without excessive focussed ionizing radiation, that is, to cause radio-sulfur to decay into carbon (that is, not without being put in an H-bomb.)
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    You know what? I'm not buying this one because there is no such thing as pinging at idle and no chance of carbon causing this if you are hearing this with a cold engine.

    I think you might have very noisy injectors or an exhaust leak or...???

    Does this engine use a timing chain or belt?
  • I have a 91 explorer with the same problem, 150,000 and have had it at the dealer for decarbing at least 2 times a year, very persistant problem, until i started using 89 octane gas from chevron, havent been back to the dealer since then, its been about 2 years now. I have a 86 ranger 2.9 v6 216,000, and have never had problems like his, why the 4.0?
  • from the chicago tribune auto q&a, i think the columnist said that higher octane gas has more cleaning additives than the 87 octane. given that premium is about 20 cents a gallon more, would a 99 cent bottle of gas additive/fuel injector cleaner do the same thing?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Nah, that stuff is harmless as a cleaner. There are good additives around but not that cheap stuff, which I think is just kerosene and a few other mild useless chemicals.

    Besides, if he has this noise at idle, octane is not his problem. There is no load on the engine at idle, so pre-ignition really can't happen.

    Perhaps his highway speed noises are octane related but not his idle noises. He has to look at injectors, noisy lifters, things like that. I can't recall if this engine is chain driven or not, but that would be another good bet.
  • I have been told that the heavy pinging at freeway speed that i experience, is pre-ignition from the glowing hot carbon deposits in the combustion chamber and on top of the piston heads.
    And yes this engine is chain driven
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    No, I don't think your pinging is from that. Hot carbon deposits mostly cause POST ignition, not as likely to cause pre-ignition. Post Ignition is engine "run-on" --that is, when you shut the ignition off and the engine keeps on going.

    If you have some clatter at idle, you should definitely put an ear to your timing chain, and if you DON'T have post-ignition (engine run on) I would rather doubt you have excessive carbon build up.

    If you are pinging loudly at freeway speeds, I think you have an engine management problem, with some sensor that controls engine timing; also, pinging and a loose timing chain have a relationship worth exploring.

    So far, I think this car is being mis-diagnosed. If there were more data I might change my opinion, but given what's on the board, that's what I think right now.
  • jcasperjcasper Posts: 37
    The first time I noticed this noise was shortly after I bought it. I was sitting in a parking lot waiting for someone and I had the engine idling (30,000 Miles). I took it to the dealer figuring that something was loose and rattling. There diagnosis then was that something was loose in the catalytic converter. (they replaced that under warranty). Shortly after leaving I still could notice the noise and told the dealer that there was still a rattling noise and they needed to investigate further. At this time I was also starting to notice a pinging while driving on the freeway. The dealer came up with a TSB from ford stating that this motor was prone to excessive carbon buildup and instructed them to check the MAF sensor and if everything was O.K. they were to decarbon the motor and leave it at that. After they do this decarboning the motor is quiet for a short while (a couple months). The TSB also stated that the motor needed to be run over 3000 RPM every day to keep the motor clean. On a couple trips I've made to the beach or over the mountain on long steep grades I will lock the transmission down in second gear and drive up the hill running the motor around 4500 RPM for a sustained period and this seems to help. The noise will be less noticeable for a couple weeks. Right now at 65,000 miles the car runs good except for this noise wich I am afraid could be damaging my motor, and currently the noise is the worst at around 70-75 MPH. On startup there is a little rattle but I assume that is probably just a dry motor rattling. I have always been very good with maintenance and always run good quality gas, Premium does not seem to make a difference except on my wallet.
  • swschradswschrad Posts: 2,171
    awfully hard to get an exploder up to 3k with the transmission shift points in it. I'm suspicious. have another mechanic evaluate this.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Me, too. If you are actually pinging loudly at 75 mph this is really not a good thing.

    That "pinging" by the way, is actually the internal parts of your engine rattling around like a chicken grabbed by a terrier. In extreme cases, the actual cylinder walls of the block will flex. Typical damage from severe pinging is a hole through the top of the piston.

    Heavy and sustained pinging is very dangerous...a light and brief ping now and then is not.
  • wijocowijoco Posts: 462
    From the sound of things, no one has even been able to isolate the source of your noises. The catalytic converter is a long way from the top half of the engine. You need to take it to get a second and maybe third opinion to locate your noises. It's entirely possible you have two separate sounds, like an exhaust heat shield rattle at idle and a motor knock at speed. Let us know when you've isolated the noises. Until then it's just a million guesses.
This discussion has been closed.